US20130014636A1

US20130014636A1 - Blast absorbing cladding

Info

Publication number: US20130014636A1
Application number: US13/544,804
Authority: US
Inventors: Tejav Dehghanyar; Michel Michno
Original assignee: Enclos Corp
Current assignee: Enclos Corp
Priority date: 2011-07-08
Filing date: 2012-07-09
Publication date: 2013-01-17

Abstract

A blast resistant cladding includes a curtainwall arranged on a structure and defines a load path for transferring loads imparted on the curtainwall to the structure and an absorbing system positioned along the load path and configured for absorbing blast-type loads imparted on the curtainwall.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC §119(e) to U.S. Patent Application No. 61/505,610 filed Jul. 8, 2011 entitled “Blast Absorbing Cladding” which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure relates to mitigating blast loads imparted on building cladding. More particularly, the present disclosure relates to an absorbing system for mitigating blast loads on cladding thereby reducing the effect of the loads on the cladding as well as the building structure. Still more particularly, the present disclosure relates to an absorbing system incorporated into a curtainwall anchor for mitigating blast loads.

BACKGROUND

In the wake of several terrorist attacks within the U.S. there has been a heightened level of protection provided by Federal, State, and Local law enforcement agencies. These efforts have included increased security measures and increased numbers of security personnel, particularly at highly attended and/or particularly vulnerable events. These efforts have also included putting additional thought into and conducting studies on how to minimize vulnerabilities when constructing new facilities and structures. Some of this additional thought and study relates to restricting access and providing more control over logistics of public and private entrances and exits to and from facilities. In some instances, where restricted access, separation, or other known techniques are not available or desirable, reinforcement of the vulnerable portion of the facility may be another solution.
In a building structure, the building façade is often the first line of defense against an attack on a structure. Where explosives, projectiles, or other dangerous systems are used near or directed toward a building, the building façade is likely the first portion of the building that will be contacted. The building façade, often formed of a curtainwall type structure, can be reinforced in an effort to better resist, for example, blast forces. However, the strength required to resist such forces is often balanced with the increased costs associated with it. In some cases, the increased costs may be justifiable and affordable, but in other cases, safety may be compromised due to costs, an aesthetic desire of the facility owner, or other limitations on reinforcement of the curtainwall system.
The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of invention is to be bound.

SUMMARY

In one embodiment, a blast resistant cladding may include a curtainwall arranged on a structure defining a load path for transferring loads imparted on the curtainwall to the structure. The cladding may include an absorbing system positioned along the load path configured for absorbing blast-type loads imparted on the curtainwall.
In another embodiment, a system for supporting exterior cladding and resisting blast forces imparted thereon may include a cladding interface for fixedly engaging the cladding, a structure interface for fixedly engaging the structure, and an engagement system positioned between the cladding interface and structure interface. The engagement interface may include a hanger system for vertically supporting the cladding and a bracing system for laterally supporting the cladding. The bracing system may include an absorbing system for absorbing the blast forces.
In still another embodiment, a blast resistant cladding may include a curtainwall arranged on a structure defining a load path for transferring blast-type loads imparted on the curtainwall to the structure and a means for absorbing blast-type loads imparted on the curtainwall.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other features, details, utilities, and advantages of the present invention will be apparent from the following more particular written description of various embodiments of the invention as further illustrated in the accompanying drawings and defined in the appended claims.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is an exterior perspective view of a building clad with a curtainwall system according to the present disclosure and subject to an external blast.

FIG. 2A is a perspective view of a curtainwall unit of the system of FIG. 1.

FIG. 2B is a schematic diagram of the blast load of FIG. 1 passing through the curtainwall unit of FIG. 2A.

FIG. 2C is a dynamic model of the blast load of FIG. 1 passing through the curtainwall unit of FIG. 2B.

FIG. 3 is an interior perspective view of the curtainwall unit of FIG. 2A showing an anchor system securing the curtainwall unit to a floor of the building.

FIG. 4A is an interior perspective view of an anchor system according to one embodiment.

FIG. 4B is a partial exploded perspective view of the anchor system of FIG. 4A.

FIG. 5A is an exterior perspective view of the anchor system of FIG. 4A.

FIG. 5B is a cross-sectional top view of a portion of the anchor system of FIG. 5A taken about line 5B-5B.

FIG. 5B-1 is a cross section of a portion of the anchor system of FIG. 5A taken about line 5B1-5B1

FIG. 5C illustrates an embodiment of the anchor system of FIG. 4A wherein a damping device is used in other locations within the system.

FIG. 5D depicts a side view of an embodiment of the anchor system that may be used with a wall system according to aspects of the present disclosure.

FIG. 6 is an interior perspective view of an anchor system according to another embodiment.

FIG. 7 is an interior perspective view of an anchor system similar to FIG. 6 and including an additional bracing system.

FIG. 8A is a close-up view of the bracing system of the anchor system of FIG. 7.

FIGS. 8B-8D illustrate various embodiments of a damping device that may be used in the bracing system of FIG. 8A.

FIGS. 9A-9B depict clips that may be used with an anchor system according to aspects of the present disclosure.

FIG. 9C illustrates an embodiment of the anchor system of FIG. 9A wherein a damping device is used in other locations within the system.

FIG. 10A is an interior perspective view of an anchor system according to another embodiment.

FIG. 10B is an exterior perspective view of the anchor system of FIG. 10A.

FIGS. 11A-11C are perspective views of several engagement systems for use with the anchor system of FIG. 10A.

FIG. 12 is a comparative displacement diagram showing the displacement of a curtainwall mullion with a rigid support condition compared to that of a flexible support condition.

FIG. 13 is a comparative stress diagram showing the stress of a curtainwall mullion with a rigid support condition compared to that of a flexible support condition.

FIG. 14 is a hysteresis diagram showing the stress v. displacement of a curtainwall mullion with a rigid support condition.

FIG. 15 is a hysteresis diagram showing the stress v. displacement of a curtainwall mullion with a flexible support condition.

FIG. 16 is a comparative displacement diagram showing the displacement of a 10″ mullion with a flexible support as compared to that of a 7″ mullion with a flexible support.

FIG. 17 is a comparative displacement diagram showing the stress of a 10″ mullion with a flexible support as compared to that of a 7″ mullion with a flexible support.

DETAILED DESCRIPTION

The present disclosure relates to an absorbing system for mitigating blast loads imparted on the cladding of a building. The absorbing system may be positioned at any point along the blast load path and may be configured to transfer some of the blast load and absorb the remaining portion of the blast load. Accordingly, when passing through the absorbing system, the blast load may be at least partially absorbed thereby reducing the effect of the load on the components of the cladding and the building structure.
The absorbing system may include one or a combination of several devices configured for absorbing and transferring loads. In some embodiments, the absorbing system may include damping pads positioned along the blast load path and oriented substantially orthogonally to the path. The damping pads may be configured to absorb the load much like a combined spring and shock absorber or imperfect spring. In other embodiments, the absorbing system may include damping pads oriented substantially parallel to the load path. The damping pads, in this embodiment, may be configured to absorb the load similar to the system above, but by way of shear deformation rather than compressive or tensile deformation. In still other embodiments, the absorbing system may include elements adapted for inelastic deformation, sliding friction, or other energy absorbing mechanisms or devices. Advantageously, the dampening approaches described herein may improve the performance of the system not only under initial load but also by diminishing or reducing damage caused during rebound of the system.
With reference to FIG. 1, one form of cladding, for which the absorbing system may be used, may include a curtainwall system 100 that is supported by hanging from the structure of a building 102. For purposes of understanding the load path, at least one example of a curtainwall 100 will be described. As shown in FIG. 2A, the curtainwall 100 may include a series of curtainwall units 108 with vertically extending mullions 104 positioned on each side of the unit 108. The curtainwall unit 108 may also include horizontally extending transoms 110 at one or more locations throughout the height of the unit 108. In addition, the unit 108 may have portions of spandrel glass 112 or other material at or near the floor locations 106 and may have transparent or semi-transparent glass 114 arranged in between the floors 106. The curtainwall unit 108, as best shown in FIG. 3, may be supported off of the floor 106 with anchors 105 adjustably connected to the floor 106 and the curtainwall mullions 104. It is noted that FIG. 3 shows an interior finish system without openings and has been provided primarily to show the anchor system location.
Other cladding systems may also be provided. For example other curtainwall systems such as that described in U.S. patent application Ser. No. 11/532,360 filed on Sep. 15, 2006 and entitled Curtainwall System, the contents of which are hereby incorporated by reference herein in their entirety, may be provided. In addition, the curtainwall described in U.S. Patent Application No. 60/867,341 filed on Nov. 27, 2006 and entitled Dual Wall System, the contents of which are hereby incorporated by reference herein in their entirety, may also be provided. Other curtainwall types may also be provided. Still other cladding systems may include, for example, stone on truss type cladding, cladding applied to studs, precast panels, window walls, and other cladding systems suspended from a structure. More particularly, the systems described herein may be applied to pre-cast panels, stick wall systems and to studs on sheathing supporting rain screen systems such as panels, stone and terra cotta.
With reference again to FIG. 1, the curtainwall 100 may encounter loads emanating from a blast 101 occurring near or around the building 102. Having described a typical curtainwall 100 structure, the load path of a blast load, for example, may be described with reference to FIG. 2B. The load path may begin on an outer surface of the curtainwall 100 and travel inward toward the building structure. The load may be distributed by the glass 112 or other material 114 making up the surface of the curtainwall 100 and may be transferred through a sealant 118 to the supporting transoms 110 and mullions 104. The load in the transoms 110 may be collected by the mullions 104 and transferred to the structure through an anchor 105 to the support structure of the building 102. As best shown in FIG. 2A, the mullions 104 of the curtainwall 100 may transfer this load by being designed to span between adjacent floor systems 106 of the building 102. The blast may be resisted by the mullions 104 in flexure and shear as depicted by the deflected shape of the curtainwall in FIG. 1. That is, under loads imparted by the blast force, the curtainwall 100 may have a bending and shear capacity configured to resist these loads while spanning the distance between the floors 106. The loads resisted by the curtainwall 100 may then be transferred into the floor systems 106 by the anchors 105 that are positioned on the edge of the floor system 106 to support the curtainwall 100.
Aside from the absorbing system being provided and described herein, a curtainwall system 100 may have some ability to absorb load. As shown in FIG. 2C, each of the transitions between a given part or element of the curtainwall unit 108 and an adjoining or adjacent part or element may provide a dynamic resisting element 120. Each dynamic resisting element 120 may function to transfer and absorb a portion of the force passing between the parts of the curtainwall unit 108 based on its stiffness and damping characteristics. Accordingly, each of the dynamic resisting elements 120 can define a spring constant 122 and a viscous damping constant 124. That is, for example, the sealant 118 between the glass 112, 114 and the mullion 104 may have a stiffness or spring constant Ks 122A and a viscous damping constant Cs 124A. The connection between the mullion 104 and the anchor 105 may have a spring constant of Km 122B and a viscous damping constant Cm 124B. Additionally, the connection of the anchor system 105 to the building or floor 106 may have a spring constant Ka 122C and a viscous damping constant Ka 124C. As the load passes through each of these dynamic resisting elements 120, the energy of the imparted load may be partially transmitted and partially stored based on the stiffness of the particular element 120. The stored energy may then be released, but damped according to the viscous damping constant. As the element 120 continues to store and release energy in an oscillating manner, the damping characteristics of the materials may eventually dissipate all of the oscillation. A typical curtainwall system 100 as described may have a stiffness, when considering all of the dynamic resisting elements, on the order of 500 kips/inch. Other stiffnesses may also be provided depending on the materials and connections selected for the system.
With the context provided above, several embodiments of an absorbing system may be described. It is noted that the embodiments disclosed herein include an absorbing system associated with the connection of the mullions 104 of the curtainwall 100 to the building structure. This particular location for the absorbing system can be advantageous because it reflects a logical break in the load path relating to the assembly and installation of the cladding. However, as mentioned, it is within the scope of the present disclosure to position the absorbing system anywhere along the load path.
The embodiments disclosed herein include a securing device for securing exterior cladding to a building. The securing device can be an anchor system 105 configured to support a curtainwall 100 relative to a building structure. The anchor system 105 can include several elements adapted to suspend the curtainwall 100 from the building and allow for adjustment during installation. Moreover, the anchor system 105 may include a bracing system for bracing the curtainwall laterally relative to the supporting structure thereby accommodating wind loads, internal building pressures differentials, blast loads or other lateral acting loads imparted on a curtainwall system. The absorbing system may be incorporated into the bracing system allowing the anchor to more effectively absorb blast forces imparted on the exterior or interior of the curtainwall 100. Accordingly, the absorbing system may reduce the effect of forces imparted on the curtainwall 100 thereby allowing for a more economical and safe solution. That is, the absorbing system may allow the curtainwall 100 and the building structure to be more resistant to imparted loading without needing to be unduly reinforced.
With reference to FIGS. 4A-5B, a first embodiment of an anchor system 150 may be described. As shown in FIGS. 4A-4B, the anchor system 150 may include a curtainwall anchor with a curtainwall interface 152 configured for secured connection to a mullion 104 of the curtainwall unit 108. The system 150 may further include a structure interface 154 configured for secured connection to a base. For example, the structure interface 154 may be configured for connection to a floor slab 106 of a building 102. The curtainwall interface 152 and the structure interface 154 may each be configured to both vertically and laterally support the curtainwall 100 and an engagement system 156 may be provided to connect the two. The engagement system 156 may include a hanger system 158 for transferring vertical support loads between the two interfaces 152, 154 and a bracing system 160 for transferring lateral acting support loads between the two interfaces 152, 154. The bracing system 160 may include an absorbing system 162. It is noted that, while a single curtainwall interface element 152 is shown, two or more may be provided as shown in FIGS. 4A-5B. Similarly, while a single engagement system 156 has been shown and a single set pads in the absorbing system 162 are shown, two or more of these elements may also be provided.
With continued reference to FIGS. 4A-5B, each of the elements of the anchor system 150 may be described in more detail. The curtainwall interface 152 may generally be a device providing for engagement of the mullion 104 or other portion of the curtainwall 100. As such, the curtainwall interface 152 may be a lip, ledge, loop, rib, pin, rod, hole, or other feature allowing for engagement of the curtainwall 100. The curtainwall interface 152 may be attached to or integral with mullion 104 or other portion of the curtainwall 100. With reference to FIGS. 4A and 5A-5B, the curtainwall interface 152 may take the form of a pair of mullion brackets or fists. For purposes of further discussion, the curtainwall interface 152 will be referred to as a fist 152. In some embodiments, the mullion 104 and fist 152 may be made of steel, stainless steel, or other appropriate material.
The fist 152 may include a securing portion 166 and an adjustment portion 168. The securing portion 166 may be adapted for positioning adjacent to and securing to the mullion 104. Where the mullion 104 is a rectangular element, with relatively flat sides, the securing portion 166 may also be flat in the form of a plate and may be positioned on or coupled to the surface of the mullion 104. The securing portion 166 may be constructed of steel, aluminum, other metals, an alloy, or a composite material. Other materials may also be used. In the case of a steel securing portion 166 in the form of a plate, the plate may have a thickness ranging from approximately ⅛″ to approximately ¾″. In other embodiments, the plate may have a thickness ranging from approximately 3/16″ to approximately ⅝″. In still other embodiments, the plate may be approximately ¼″ thick. Thicker or thinner plate thicknesses may also be provided. The securing portion 166 of the fist 152 may be fastened to the mullion 104 with a plurality of fasteners 167 such as screws, bolts, self-tapping screws, self-drilling screws, or other fasteners. In other embodiments, the securing portion 166 may be welded or otherwise secured to the mullion 104 or may be an integral portion of the mullion 104. For example, the securing portion 166 may be extruded together with the mullion 104.
As mentioned, in addition to the securing portion 166, the fist 152 may include an adjustment portion 168 and the adjustment portion 168 permits adjustment of the mullion 104 relative to the support structure or building 102 in one of a lateral and horizontal direction or both. In the embodiment shown, the adjustment portion 168 is configured for vertical adjustment. The adjustment portion 168, as seen in FIGS. 5B and 5B-1, may include a hollow shaft structure 170 formed by a shaft wall 172 extending along the vertical length of the securing portion 166. The shaft structure 170 may be configured to allow an adjustment element 203 to translate vertically along the length of the shaft 170. As shown, the shaft wall 172 may be generally cylindrical and may extend fully along the length of the securing portion 166. In other embodiments, the shaft wall 172 may extend partially along the securing portion 166 or beyond the securing portion 166. The shaft wall 172 may have a longitudinal adjustment control 173 in the form of a helical thread 173 on an inner surface providing for screw-like propagation of an adjustment screw, for example, that, in turn, adjusts the position of the adjustment element 203 along the length of the shaft 170. Other longitudinal adjustment controls 173 can also be used such as, for example, ratchet features and pin and socket features. The shaft 170 may also include an elongate opening 174 extending fully or partially along its length allowing elements to extend through the shaft wall 172 into the shaft 170 and, for example, connect to the adjustment element positioned in the shaft 170. The elongate opening 174 may have a width at least slightly smaller than the corresponding shaft dimension to prevent escape of the adjustment element 203 laterally through the shaft wall 172. For example, where the shaft 170 has a circular cross-section, the width of the elongate opening 174 may be at least slightly smaller than the diameter of the shaft 170. The adjustment portion 168 may be made from the same material as the securing portion 166 and they may be extruded or molded as a single piece after which the helical threads may be cut into the shaft 170.
As mentioned, the anchor system 150 may include a structure interface 154 in addition to the curtainwall interface or fist 152. The structure interface 154 may be coupled to or configured for connection to the surface of a concrete slab 106 near an edge, for example. In other embodiments, the structure interface 154 may be positioned in or coupled to an embed and secured to the embed. For example, the structure interface 154 may be provided as shown and described in any or all of U.S. patent application Ser. No. 11/208,444 filed on Aug. 19, 2005, Ser. No. 12/422,754 filed on Apr. 13, 2009, and Ser. No. 12/422,799 filed on Apr. 13, 2009, each entitled Adjustable Attachment System. The contents of each of these applications are hereby incorporated by reference herein in their entireties. In still other embodiments, the structure interface 154 itself may be in the form of an embed. In any or all of the above cases, the structure interface 154 may be configured to be secured directly or indirectly to a base element in the form of a floor system 106 of a building 102 thereby transferring vertical and lateral acting loads imparted on the curtainwall 100 to the building 102. As such, the structure interface 154 may be a bracket, plate, pin, rod, hole, or other feature allowing floor system 106 or other portion of the building 102 to be engaged with the structure interface. Similar to the curtainwall interface or fist 152, the structure interface 154 may be separate from or integral with the floor system 106 or other portion of the building 102. In some embodiments, the structure interface or bracket 154 may be made of steel, stainless steel, or other appropriate material.
In the embodiment shown in FIGS. 4A-5B, the structure interface 154 may be in the form of a bracket, floor bracket, or attachment plate. For purposes of further discussion, the structure interface 154 will be referred to as a bracket or floor bracket 154. The bracket 154 may include a generally flat or planar surface or portion 155 arranged in a horizontal orientation. The bracket 154 may include a slotted hole 176 having a longitudinal axis extending along its length. The bracket 154 may be arranged such that the longitudinal axis of the slotted hole is directed at an angle to the edge of the base or slab 106. In some embodiments, the bracket 154 may be arranged with the longitudinal axis of the slotted hole 176 extending generally perpendicularly to the edge. The slotted hole 176 may receive and slide along a bolt or other anchoring element 178 extending from the base thereby coupling the bracket 154 to the base 106. The slotted hole 176 and anchoring element 178 may allow some use slippage and friction. That is, the slotted hole 176 and anchoring element 178 may allow minimal to no movement of the system under wind load but may allow some movement of the system (within acceptable limits) to dissipate a blast load
As shown, a top surface 153 of the bracket 154 may include a gripping feature or surface 180A such as, for example, a roughened or toothed surface. A washer 182 may also be coupled to the bolt or anchoring element 178 and a bottom surface 181 of the washer 182 may also include a gripping feature or surface 180B such as, for example, a roughed or toothed surface for engaging the roughened or toothed surface of the bracket 154. A nut or other fastening element 184 couples or causes engagement of the opposing gripping features 180A/B of the washer 182 and bracket 154 thereby fixing the position of the bracket 154 relative to the bolt or anchoring element 178, and thus fixing the bracket 154 position relative to the edge of the base 106. Multiple slotted holes 176 and anchor bolts 178 may be provided to prevent twisting of the bracket 154 about the bolt or anchoring element 178 or to provide more strength. As shown, where more than one slotted holes 176 are provided, the slotted holes 176 may be arranged generally parallel to one another to facilitate an adjustable position of the bracket 154 by sliding the bracket 154 relative to the anchor bolts 178 prior to installing the washer 182 and nut 184.
In addition to the flat surface or portion 155, the bracket 154 may include an upturned leg 186 arranged generally perpendicular to the flat surface 155 and extending laterally from the edge of the bracket 154. The upturned leg 186 may include an inboard surface 188 facing the building or structure 102 and an outboard surface 190 facing away from the building or structure 102. The upturned leg 186 may also include a cap bearing element 192 positioned on the top edge of the leg 186 and extending along the length of the leg 186. In cross-section, the cap bearing element 192 may have a relatively flat top surface and may have arcuate upper corners transitioning into relatively vertical sides and a relatively flat bottom surface. In other embodiments, the cap bearing element 192 may have a circular or other cross-section. The cap bearing element 192 may have a width or circumference slightly larger than the width or thickness of the upturned leg 186 of the bracket 154 and it may be centered on the upturned leg 186 causing the cap bearing element 192 to overhang the upturned leg 186 on each of the outboard and inboard faces 188, 190 creating leg cavities 194. The bracket 154 may have a width, measured along the edge of the floor 106, larger than a width of a mullion 104 allowing the fists 152 secured to the sides of the mullion 104 to be connected to the bracket 154 with an engagement system 156.
As mentioned, and as indicated in FIG. 4B, the curtainwall interface or fist 152 and the structure interface or floor bracket 154 may be connected or coupled together by an engagement system 156 and the engagement system may include one of a hanger system 158 and a bracing system 160 or both. The hanger system 158 may vertically support the curtainwall 100 relative to the base 106. Accordingly, the hanger system 158 may engage the fist 152 and the floor bracket 154 in a manner that prevents or controls vertical displacement therebetween. The bracing system 160, on the other hand, may be configured to laterally support the curtainwall 100 relative to the base 106. Accordingly, the bracing system 160 may engage the fist 152 and the floor bracket 154 in a manner that prevents or controls horizontal displacement therebetween. The engagement system 156 including the hanger system 158 and bracing system 160 may include a single integral piece of material with several parts or the systems may be separate parts that are coupled together. In the embodiments shown herein, the engagement system 156 includes a hook that both vertically supports and laterally braces the curtainwall relative to the base 106. In some embodiments, the engagement system 156 may also be fixedly secured to the structure interface 154.
Turning first to the hanger system 158, it may include a device, a portion of a device, or system of devices adapted for engaging the fist 152 and the floor bracket 154 and hanging the curtainwall 100. As such, it may include a hook, lip, ledge, tab, pin, rod, or portion thereof configured to connect the fist 152 to the floor bracket 154. With reference to FIGS. 4A-5B, in one embodiment, the hanger system 158 is provided as a portion of a hook. That is, the portions of the hook that function to provide vertical support are included in the hanger system 158.
As indicated in FIGS. 4A and 5B and others, the hanger system 158 may include a fist engaging portion 196 and a floor bracket engaging portion 198. The fist engaging portion 196 may include a main body portion 200, a tab element 202, and an adjustment element 203. The main body portion 200 may be positioned adjacent or inline with the shaft 170 of the fist 152 and may be configured for movement along the length of and parallel to the shaft 170. The main body portion 200 may be a generally flat plate-like element or another shape may be provided. The tab element 202 may extend from the main body portion 200 through the elongated slot 174 in the shaft wall 172 of the fist 152 and may be connected to the adjustment element 203 previously described as being positioned in the shaft 170 of the fist 152. The fist 152 may include piston adjusters or screws that control the vertical position of the adjustment element 203 within the shaft 170 and as such also control the vertical position of the hanger system 158. For example, the piston adjusters may be threaded elements that move vertically within the shaft 170 through a screw-type engagement with the inner surface of the shaft 170.
In some embodiments, the floor bracket engaging portion 198 may be a tab, lip, rod, or other element which extends from the main body 200, bears on or otherwise engages the floor bracket 154, and prevent relative vertical displacement between the fist engaging portion 196 of the hanger system 158 and the floor bracket 154. One embodiment of the floor bracket engaging portion 198 shown in FIGS. 4A, 4B and others, is in the form of a boom type structure extending from the main body 200 of the fist engaging portion 196. For purposes of discussion, the floor bracket engaging portion 198 will be referred to as a boom 198.
The boom portion 198 may be fixedly secured to the main body 200 to prevent displacement and rotation therebetween. For example, the boom 198, like the main body 200, may be a plate-like element and may be formed together with the main body portion 200 from a single piece of material. The boom 198 may extend substantially horizontally from the main body 200 and may bear on top of the upturned leg 186 of the floor bracket 154. More particularly, the boom 198 may bear on the top surface of the cap bearing element 192 positioned on the top of the upturned leg 186.
As described, the hanger system 158 may provide vertical support to the curtainwall 100 by way of the adjustment element 203 engaging the shaft 170. The adjustment element 203 may be rigidly connected or coupled to the tab element 202, which may be rigidly connected or coupled to the main body 200, which may be rigidly connected or coupled to the boom 198 and the boom 198 may bear on the floor bracket 154. It is noted that the offset nature of the support of the curtainwall 100 at the fist 152 relative to the bearing point on the floor bracket 154 may induce a moment in the hanger system 158. In other embodiments, the support of the curtainwall 100 at the fist 152 relative to the bearing point on the floor bracket 154 may be in-line rather than off set. The main body 200 together with the tab element 202 and adjustment element 203 positioned in the shaft 170 may have a height H, measured along the fist 152, adapted to resist the induced moment. In one embodiment, the main body 200 may have a height between approximately ½ inch and approximately 4 inches. In another embodiment, the main body 200 may have a height up to and including approximately 2 feet. In another embodiment, the main body 200 may have a height between approximately 1 inch and approximately 3 inches. In still other embodiments, the main body 200 may have a height of approximately ½ inches. In still other embodiments, the main body 200 may be longer than approximately 4 inches or shorter than approximately ½ inch and may have a length similar to the spandrel height of the associated curtainwall, for example. Suitable heights may be selected to resist the imparted loads and also accommodate desires to keep the portions of the anchor secluded and out of sight. Other heights may also be provided.
As mentioned, the engagement system 156 for connecting or engaging the curtainwall interface or fist 152 and the structure interface or floor bracket 154 may include a bracing system 160 in addition to the hanger system 158 just described. The bracing system 160 may be separate from or partially integral with the hanger system 158. In the embodiment shown in FIGS. 4A to 5B, the bracing system 160 may be said to be partially integral with the hanger system 158 since it extends from the hanger system 158 and relies on the main body 200, tab element 202, and adjustment element 203 to prevent horizontal displacement relative to the fist 152. The bracing system 160 further includes elements secured to and extending from the hanger system 158 to provide lateral bracing relative to the floor bracket 154. As shown, the bracing system 160 may include an inboard hook leg 206 extending vertically downward from the boom 198 along the inboard face 190 of the upturned leg 186 of the floor bracket 154. The inboard hook leg 206 may be fixedly secured or otherwise coupled to the boom 198 to prevent displacement and rotation therebetween. For example, the hook leg 206 may also be part of the same material as the main body 200 and boom 198. The boom 198 and inboard hook leg 206 may form a generally L-shaped member and may together be referred to as a hook. In addition, the main body 200 may also form a portion of the hook and the hook may be generally U-shaped. The term hook may also be used to refer to the element including the main body 200, the tab element 202, the adjustment element 203, the boom 198, and the vertical hook leg 206. In some embodiments, the elements of the hook may be made of steel, stainless steel, or other appropriate material.
Accordingly, as mentioned, the engagement system 156 may include a hanger system 158 and a bracing system 160, each of which may be separate parts or may be formed by a portion of a single part. In the embodiment described, the hanger system 158 and bracing system 160 are partially integral in that they each include portions of the hook which connects the fist 152 to the floor bracket 154. In some embodiments, as mentioned, the engagement system 156 may be further integral with the structure interface 154 by being fixedly or slidingly secured or otherwise coupled thereto.
As can be understood from FIGS. 4A, 4B, 5A and others, the bracing system 160 may further include an absorbing system 162 including distribution elements 208 and damping devices 212. With respect to distribution elements 208, first or outboard distribution element 208 a may be secured to the main body 200 of the hanger system 158 and a second or inboard distribution element 208 b may be secured to the vertical hook leg 206. The distribution elements 208 may be configured for handling lateral acting forces by being positioned normal to the force direction and, thus, the absorbing system 162 shown may be referred to as a normal force-type absorbing system 162. Accordingly, and as can be seen in at least FIG. 5A, the distribution elements 208 may include a generally planar or damping surface oriented in a plane adjacent and parallel to the plane defined by the corresponding inboard or outboard face 188, 190 of the upturned leg 186 of the floor bracket 154. The planar surfaces of the distribution elements 208 may be separated from the respective faces 188, 190 of the upturned leg 186 defining a space 209 therebetween. As explained in more detail below, the damping devices 212 are received in the space 209. The distribution elements 208 may be plate elements as shown or may have some other shape adapted to more readily distribute loads. For example, the distribution element 208 may have a triangular cross-section when viewed from above, from the side, or both. In this embodiment, for the outboard distribution element 208 a, for example, the apex of the triangle may abut the main body 200 and the base of the triangle may form the planar surface adjacent the outboard face 190 of the upturned leg 186. In other embodiments, rather than modifying the shape of the distribution element 208, the thickness, measured perpendicular to the planar surface, may be increased or selected to suitably distribute lateral acting loads. Generally, a thicker distribution element 208 may provide for more load distribution.
The damping device 212 may be configured for absorbing and damping loads passing through the bracing system 160. In some embodiments, the damping device 212 may include a energy storing and releasing device such as a spring, for example, and a shock absorber using fluids such as a dash pot device, for example. In some embodiments, the energy storing/releasing function and dash pot or damping function may be provided by a single device. In the present embodiment, as shown in FIGS. 4A, 5B and others, the damping device 212 may be provided in the form of a damping pad or pads 212. In the embodiment shown, the damping pads may be normal force-type damping pads and may be particularly adapted to transfer and dissipate loads imparted normal to the surface of the pad. The damping pads 212 may be positioned in the space 209 between the distribution elements 208 and respective inboard and outboard faces 188, 190 of the upturned leg 186 of the floor bracket 154. In this position and orientation, the damping pads may transfer and dissipate lateral acting loads through compressing and stretching. The pads may be adhered or otherwise secured to the distribution elements 208 or the inboard and outboard faces 188, 190 of the upturned leg 186 of the floor bracket 154 or both. The damping pads may include an elastomeric material such as for example, rubber, neoprene, ethylene propylene rubber (EPM), or ethylene propylene diene rubber (EPDM). Other materials, including other elastomeric materials, can also be used. In some embodiments, the damping pad may include lead or other internal materials for increasing the internal friction of the material to further damp lateral acting forces or may include layers of material such as lead or brass to further damp lateral acting forces. In some embodiments, the pads 212 may be replaceable. In some embodiments, the damping device is made of a “crushable” material such as sand, stone, plaster board. cement board or other appropriate material that could absorb a blast. A device 212 made of such crushable material may be configured as a replaceable insert.
While the distribution element 208 has been described as being arranged on the hook and not on the floor bracket 154, the upturned leg 186 of the floor bracket 154 may form an opposing distribution element for positioning of the damping device 212 therebetween. In other embodiments, distribution element 208 may be arranged on the floor bracket 154 and a natural surface of the hook may oppose the distribution for placement of a damping device 212 therebetween. In other embodiments, the absorbing system 162, or elements of the absorbing system 162, are placed in other locations along the load path. For example, in one embodiment shown in FIG. 5C, the damping pads 212 may be positioned between the mullion 104 and the fist 152. In this position and orientation, the damping pads may transfer and dissipate lateral acting loads by shear deformation or compressive deformation of the pad. Additionally or alternatively, the damping pads 212 may be positioned or coupled between the floor bracket 154 and the slab floor 106. In this position and orientation, the damping pads may transfer and dissipate lateral acting loads by compressive or tensile deformation of the pad. In other embodiments, such as a system shown in FIG. 5D, where the system is a wall system 500 comprised of cassettes 502 applied to support framing 504, the damping pads 212 may be positioned between the cassettes 502 and the frame 504. It can be appreciated that any of the above-described systems can also use the damping pads described elsewhere herein, such as the layered damping pads 312 discussed with reference to FIGS. 6-8.
The damping pads may have a neutral (i.e., unstressed) thickness substantially equal to the space between the distribution elements 208 and the faces 188, 190 of the upturned leg 186. In some embodiments, the thickness of the damping pads may be between approximately 1/16 inch and approximately 1 inch. In other embodiments, the thickness may be between approximately ⅛ inch and approximately ½ inch. In still other embodiments, the thickness may be approximately 3/16 inch. Multiple layers of damping material may be provided and adhesives may be provided between the layers. The layers of damping material may all be the same material or several types of material may be provided in the several layers. The thickness of the damping pads may be selected to accommodate the space available within the wall in addition to other load considerations. That is, for wind loads, for example, limitations for allowable deflections must be met, so highly flexible and low resistant materials may not satisfy these requirements.
The distribution elements 208 in conjunction with the damping device 212 may allow the absorbing system 162 to distribute lateral acting loads to a relatively larger area of the upturned leg 186 of the floor bracket 154. The distribution of the force over a larger area may reduce the force per unit area that is being transferred and dissipated thereby increasing the efficacy of the system. In some embodiments, the surface area of the planar surface for each distribution element 208 and the size of the damping pads may be between approximately ¼ square inches and 9 square inches. In other embodiments, the area may be between approximately ½ square inches and 4 square inches. In still other embodiments, the area may be approximately 1 ½ square inches. Larger or smaller areas may also be provided.
It is noted that under lateral acting loads, the horizontally offset nature of the position of the bracing system 160 and corresponding absorbing system 162 relative to the longitudinal axis of the shaft 170 of the fist 152 may induce horizontal rotation of the bracing system 160 about the longitudinal axis of the fist shaft 170. As shown in FIGS. 5A-5B, a keyway 210 may be provided extending longitudinally along the internal surface of the shaft 170 and a corresponding key 211 may be provided on the adjustment element 203 positioned in the shaft. In one embodiment, the key 211 may be two tabs extending from or integral with the cylindrical adjustment element 203 that correspond and engage with the keyway 210. In other embodiments, the shape or number of adjustment elements, key and keyways may be different but the key and keyway will correspond in number and shape with each other. As such, the adjustment element 203, tab element 202, and main body 200 of the hanger system 158 may be prevented from twisting relative to the fist 152.
With reference to FIGS. 6-8, a second embodiment of an anchor system 250 may be described. The anchor system 250 shown may be similar to the anchor system 150 described with respect to FIGS. 4A-5B. That is, the anchor system 250 may include a curtainwall interface in the form of a bracket or fist 252 and may also include a structure interface in the form of a bracket, floor bracket, or plate 254. Still further, the engagement system 256 may include a hanger system 258 with a fist engaging portion 296 having a main body 300, a tab element 302 and an adjustment element 303 in addition to a floor bracket engaging portion or boom 298 in bearing relationship on the top edge of the upturned leg 286 of the floor bracket 254. In contrast to the anchor system 150 described with respect to FIGS. 4A-5B, the present anchor system 250 may include a shear force-type bracing system 260 and corresponding absorbing system 262 rather than a normal force-type bracing system 160 and absorbing system 162. In further contrast to the bracing system 150, the absorbing system 262 of the bracing system 260 may be positioned to isolate the bracing system 260 from the hanger system 258.
Accordingly, the bracing system 260 shown may be partially integral with the hanger system 258 like the bracing system 160 of FIGS. 4A-5B. That is, the bracing system 260 may extend from the hanger system 258 and thus rely on some lateral force transfer through the hanger system 258. However, the damping device 312 may be positioned between the hanger system 258 and the bracing system 260 rather than between the bracing system 260 and the floor bracket 254. Like the bracing system 160 previously described, the bracing system 260 may be configured to transfer and dissipate lateral acting loads between the curtainwall interface or fist 252 and the structure interface or floor bracket 254.
The bracing system 260 shown may include a U-shaped hook 314 having an inboard vertical leg 316 and an outboard vertical leg 318 connected to one another by a distribution body 320. It is noted that the boom 298 of the present embodiment may include a planar surface 307 arranged generally parallel to a lateral acting force direction. Other orientations of the planar surface 307 may be provided including oblique orientations. It is noted that while the planar surface 307 shown is oriented substantially vertically, the planar surface 307 can be horizontal or at some angle between vertical and horizontal. The distribution body 320 of the hook 314 may be positioned adjacent the boom 298 of the hanger system 258 and may include a planar surface 309 positioned in a plane adjacent to and parallel to the planar surface 307 of the boom 298. The damping or planar surface 309 of the distribution body 320 may be separated from the planar surface 307 of the boom 298 defining a space therebetween. In this embodiment, the distribution body 320 and the boom 298 may function as distribution elements 308. The vertical legs 316, 318 of the hook portion 314 may fixedly extend from the distribution body 320. That is, the vertical legs 316, 318 may be secured to the distribution body 320 to prevent relative displacement and relative rotation therebetween, for example, by being part of the same plate. Each vertical leg 316, 318 may be positioned adjacent a respective inboard or outboard face 288, 290 of the upturned leg 286 of the floor bracket 254 and, as such, may be spaced from one another a distance substantially equal to the width of the bearing cap element 292. Where a bearing cap element 292 is not provided, the spacing of the vertical legs 316, 318 may be substantially equal to the thickness of the upturned leg 286 of the floor bracket 264. Clearances for installation of the hook 314 may be provided to avoid an overly tight fit of the hook 314 over the upturned leg 286 of the floor bracket 254. That is, the hook 314 is receivingly engaged with the bearing cap element 292 or the upturned leg 286 to allow for some movement (vertical, lateral) between these elements of the system as needed. As previously described, all or a portion of the engagement system 256 may be secured to the floor bracket 254 or it may be separate therefrom.
As with the previous embodiment described with regard to FIGS. 4A-5B, the present absorbing system 262 may include a damping device 312 in the form of damping pads 312 as part of the bracing system 260. The damping pads of the present embodiment may be shear force-type damping pads adapted to transfer and dissipate loading imparted parallel to the surface of the pads. In one embodiment, as shown in FIG. 6, shear force-type damping pads may be provided in the space between the distribution body 320 of the hook 314 and the boom 298 of the hanger system 358. The pads may be adhered to both the damping or planar surface 309 of the distribution body 320 and the corresponding (planar) surface 307 of the boom portion 298. For example, an acrylic adhesive may be used. Other adhesives may include epoxy, polyurethane, or polyisocyanate. Still other adhesives may also be used. In this position, and in contrast to the embodiment of FIGS. 4A-5B, the damping pads 312 may transfer and dissipate lateral acting loads through shearing deformation of the pad rather than compressive and tensile deformation.
The damping pads 312 and the corresponding planar surfaces 307, 309 may be configured to distribute the lateral acting loads over a relatively large area. Accordingly, the planar surfaces 307, 309 and damping pads 312 may have a surface area between approximately ¼ square inches and 9 square inches. In other embodiments, the area may be between approximately ½ square inches and 4 square inches. In still other embodiments, the area of the planar surface 307, 309 may be approximately 1 ½ square inches. The pad or plurality of pads may have a thickness measured between the planar surfaces 307, 309 between approximately 1/16 inch and approximately 1 inch. In other embodiments, the thickness may be between approximately ⅛ inch and approximately ½ inch. In still other embodiments, the thickness may be approximately 3/16 inch. Other sizes and thicknesses may also be used and may be selected to suitably damp loads imparted on the system.
Multiple layers of damping material may be provided and adhesives may be provided between the layers. The layers of damping material may all be the same material or several types of material may be provided in the several layers. Where multiple layers are used, the several damping pads may be adhered to one another with epoxy, polyurethane, or polyisocyanate adhesive. Other adhesives may also be used.
As with the embodiment of FIGS. 4A-5B, the damping pads may include an elastomeric material of the types listed above. In this embodiment, however, the elastomeric material may include lead or other internal friction inducing materials. The internal friction inducing materials may assist in the ability of the damping pads to dissipate loading by generating heat through internal friction as the damping pad experiences shear deformation.
In some embodiments, as may be shown best in FIGS. 8A-8D, multiple layer damping pads may include warp resisting layers 322. The warp resisting layers 322 may be constructed of a relatively rigid material and may be configured to prevent warping of the adjacent layers under shear loading. The warp resisting layers 322 may include a steel, aluminum, alloy, or other metallic layer. Other warp resisting materials may include plastics or composites. Other warp resisting materials may also be provided. In some embodiments, an adhesive used between the layers may dry or cure into a relatively rigid material providing a warp resisting layer 322.
In the embodiment shown in FIGS. 6-8A, the damping pad 312 includes three damping layers separated by two warp resisting layers 322. In other embodiments, as shown in FIG. 8B, two damping layers separated by a single warp resisting layer 322 may be provided. In still other embodiments, as shown in FIG. 8C, four damping layers separated by three warp resisting layers 322 may be provided. In still further embodiments, as shown in FIG. 8D, five damping layers separated by four warp resisting layers 322 may be provided. Any number of damping layers may be provided including those listed or more or fewer damping layers. The several layers may be separated by warp resisting layers 322 or warp resisting layers may not be provided. In some embodiments, warp resisting layers 322 may be provided between every other or every third damping layer and not between each damping layer. Other damping layer spacings and orders may be provided.
With further reference to FIG. 6, each of the hanger systems 258 is shown associated with a single bracing system 260. That is, a single hook 314 is shown connected to the boom 298 of the hanger system 358 with a plurality of damping pads. As shown in FIG. 7, multiple bracing systems 260 can be provided for each hanger system 258 thereby providing additional absorbing systems 262. As shown, two bracing systems 260 can be provided where one system is connected with damping pads to each side of the boom 298 of the hanger system 258. In other embodiments, additional bracing systems 260 may be provided by attaching additional hooks 314 to the hooks 314 shown with additional damping pads. Any number of hooks 314 and damping pad assemblies may be provided.
It is also noted that a combination of shear and normal type systems may be provided. For example, the bearing type system described with respect to FIGS. 4A-5B may be used in conjunction with the shear type system described with respect to FIGS. 6-8D. In addition, the normal type system may be used with the deformation type system to be described with respect to FIGS. 9-11. Any combination of the systems may be used to add additional layers of damping. In other embodiments, as shown in FIG. 5C, damping may be introduced between the fist 152, 252, 352, and the mullion 104, for example. In some embodiments, as also shown in FIG. 5C, damping may be introduced between the structure interface, floor bracket or plate 154, 254, 354 and the floor slab 106. A deformation type system as described with reference to FIGS. 9-11 may be used to reduce at least some of the sideways load transfer between curtainwall units through ductile failure of clips 213, such as anti-buckling clips, used in the system, as shown in FIGS. 9A-9B. For example, the clips 213, such as anti-buckling clips 213, are made of a ductile material or include a ductility feature or are connected to a component with a ductility feature to dissipate some of the sideways load on the system. One or more of the systems disclosed herein may also be used to reduce the vertical load transfer between curtainwall units through application of one of the described systems at the vertical mullion splice joints 215. That is, and as shown in FIG. 9C, a damping device 212 such as a damping pad 212 or 312 is positioned between two vertical mullions 104 at the joint to dissipate some of the vertical load on the system (the second vertical mullion 104 is not shown in FIG. 9C so that the damping pad 212 or 312 can be seen clearly). Still other combinations of the systems described may be provided.
With reference to FIGS. 9-11, a third embodiment of an anchor system 350 is described. The anchor system 350 may be similar to the anchor systems 150, 250 previously described. That is, and as shown in FIG. 10A, the anchor system 350 may include a curtainwall interface in the form of a bracket or fist 352 and may also include a structure interface in the form of a bracket, floor bracket, or plate 354. Still further, the hanger system 358 of the embodiment shown may include a main body 400, a tab element 402, and an adjustment element 403 in addition to a boom 398 in bearing relationship on the top edge of the upturned leg 386 of the floor bracket 354. In addition, a vertical hook leg 406 may extend vertically from the boom 398 along the inboard face 388 of the upturned leg 386 of the floor bracket 354. In contrast to the anchor system 150 described with respect to FIGS. 4A-5B, the present anchor system 350 may include a bracing system 360 whose absorbing system is a material ductility-type absorbing system 362 rather than a normal force-type absorbing system 162.
As best shown in FIG. 10B, the main body 400 of the hanger system 358 may extend beyond the bottom edge of the fist 352 and may extend substantially further above the upper edge of the upturned leg 386 of the floor bracket 354 when compared to the main body portion 200 of FIGS. 4A-5B. For example, the main body 400 may extend approximately ½ inch to approximately 4 inches beyond the bottom of the fist 352 and the top edge of the main body 400 may be positioned between approximately ½ inch and 4 inches above the top edge of the upturned leg 386 of the floor bracket 354. As a result of the higher upper edge of the main body 400, the boom 398 of the hanger system 358 that extends across the top edge of the upturned leg 386 of the floor bracket 354 may be substantially deeper than that shown in FIGS. 4A-5B. For example, the depth of the boom 398 may also be between ½ inch and 4 inches corresponding to the distance that the upper edge of the main body 400 extends above the top edge of the upturned leg 386.
The bracing system 360 shown, may be partially integral with the hanger system 358 like the bracing system 160 of FIGS. 4A-5B. That is, the bracing system 360 may extend from the hanger system 358. For example, the vertically extending hook leg 406 extends from the boom 398. As a result of extending from the hanger system 358, the bracing system 360 may rely on some lateral force transfer through the hanger system 358. In contrast to previously described embodiments, the absorbing system of bracing system 360 may be built into the main body portion 400 and the vertical hook leg 406.
As shown, in FIGS. 10A and 10B, the bracing system 360 may be provided by the positioning of the main body 400 and the vertical hook leg 406 against opposite sides of the cap bearing element 392 extending along the top edge of the upturned leg 386 of the floor bracket 354. That is, unlike FIGS. 4A-5B, where particular distribution elements 208 were provided, the current embodiment may rely on the edges of the main body 400 and vertical hook leg 406 bearing against either side of the cap bearing element 392. In some embodiments, as shown, damping material or spacing material, like damping system 212, for example, may be positioned in the leg cavity 407 below the cap bearing element 392 to fill the space between the edge of the main body 400 and the edge of the hook leg 406 and the inboard and outboard faces 388, 390 of the upturned leg 386 of the floor bracket 364.
The absorbing system 362 of the bracing system 360 of this embodiment may be provided by material ductility. That is, the hanger system 358 and bracing system 360 may be constructed of a ductile material such as steel, steel alloy, or other substantially ductile material. Other ductile materials may also be used. In this embodiment, the damping device 412 of the absorbing system may be in the form of a ductility feature which may help to make the main body 400 and hook leg 406 prone to ductile failure. The ductility features may be any notch, perforation, break line, or other shaped feature that may lessen the cross-sectional area available to resist the lateral acting loads. As shown best in FIG. 11, ductility features in the form of perforation patterns may be used to cause the main body 400 and hook leg 406 to be prone to ductile failure. Under a given lateral acting load, the ductile features may deform beyond the elastic limit of the material. That is, the deformation may cause the material to begin plastic deformation causing the deformation to dissipate the load rather than return the load to the system. In some embodiments, the components subject to ductile failure are replaceable. That is, the main body 400 and hook leg 406 may be replaceable within the system.
With particular reference to FIG. 11A, the ductility features may include a plurality of slot-shaped perforations 424 arranged in a chevron pattern. Each leg 426 of the chevron pattern may include one or more slot-shaped perforations 424 separated by ductile partitions 428. In the embodiment shown, three slot-shaped perforations 424 are provided. Other quantities of slots 424 can be provided. A circular perforation 430 may be positioned in the gap between the legs 426 of the chevron and may function to disperse loading directed therethrough so as to direct the loading through and generally across each leg 426 of the chevron.
With reference again to FIG. 10, where an inward directed lateral acting load is imparted on the curtainwall 100, the force may be transmitted through the fist 352 into the main body 400 of the hanger system 358 causing the edge of the main body 400 to bear against the outboard surface 390 of the leg 386 of the floor bracket 354. The fixed position of the floor bracket 354 may create an equal and opposite force on the main body 400. This equal and opposite force may spread through the chevron shaped ductility feature causing the failure of the edge of the main body 400 followed by successive failures of the partitions 428 between the slot-shaped perforations 424. Each failure may dissipate some load and the successive failure may dissipate accumulating amounts of load. It is noted that an outwardly directed force imparted on the curtainwall 100 may be resisted and dissipated in a similar manner by the circle 430 and chevron ductility feature arranged on the hook leg 406 on the inboard side of the bracket leg 406. In this case, a tensile force may be transmitted from the curtainwall mullion 104, into the fist 352, into the main body 400, and through the boom 398 to the hook leg 406. The tensile force may cause the edge of the hook leg 406 to bear against the inboard surface 388 of the upturned leg 386 of the floor bracket 354 activating the ductility feature and dissipating the load.
With reference to FIGS. 11B and 11C, a series of vertically extending slot-shaped perforations 424 are provided. The slot-shaped perforations 424 may be positioned adjacent to one another separated by ductile partitions 428. In these embodiments, like the circle and chevron ductility feature, a load imparted normal to the edge of the main body 400 or the hook leg 406 may cause a single ductility failure or a succession of ductility failures thereby transmitting a portion of the load to the floor bracket 354 and dissipating a portion of the load. As shown in FIG. 11B, a series of four slot-shaped perforations 424 may be provided. In FIG. 11C, two slot-shaped perforations 424 are provided. Any number of slots 424 may be provided including 1 slot, 3 slots, 5 slots, or another number of slots.
Other ductility features may include a plurality of circular perforations arranged in a grid or arranged in a staggered or nested grid. In still other embodiments, combinations of slots and circular perforations may be provided. In still other embodiments, triangular, rectangular, square, diamond, or other shaped perforations may be provided. In other embodiments, the ductility features may be positioned to allow the main body 400 or vertical hook leg 406 to bend relative to the boom 398.
While the absorbing system of the present disclosure has been described in detail with respect to at least three anchor embodiments, modifications or changes may be made and remain within the scope of the invention. For example, the location of the absorbing system may be modified. That is, for example, in the embodiment shown, the damping pads are positioned between the structure interface and the curtainwall interface. That is, when considering the path of the load from the curtainwall 100 to the structure 102, the load passes through the curtainwall interface, then the damping pads, and then into the structure interface. In other embodiments, the damping pads may be located, for example between the curtainwall interface and the curtainwall. For example shear force-type and/or normal force-type bracing systems may include placing damping pads between the fist and the mullion. In other embodiments, the damping pads may be located, for example between the structure interface and the structure. For example, shear force-type and/or normal force-type bracing systems may include damping pads between the floor bracket and the floor or associated embed. In still other embodiments, the damping pads or ductility type devices may be positioned between the mullion and the structure apart from the anchor system. In this embodiment, the anchor system may be provided with some lateral play or freedom to move thereby isolating the anchor system from the lateral acting load path and allowing lateral acting forces to resisted by the absorbing system located along a load path not traveling through the anchor system. In still other embodiments, the absorbing system may be positioned at any location along the load path.
As another example of a modification within the scope of the invention, the curtainwall interface and the structure interface may be one in the same. That is, the curtainwall interface and structure interface may be one integral component, such as a steel angle or other bracket, that engages both the curtainwall and the structure. In these embodiments, the damping element may be provided internally, similar to FIGS. 6-8D or FIGS. 9-11, or on either boundary of the component.
As another example of a modification within the scope of the invention, combinations of the embodiments shown may be provided. In one embodiment, combinations of normal force-type and shear force-type systems can be used. For example, the ductility features of the embodiment shown in FIGS. 9-11 may be added to the embodiment shown in FIGS. 4A-5B.
As another example of a modification within the scope of the invention, additional damping resistance or features may be added through duplication or otherwise. For example, in the embodiment shown in FIGS. 4A-5B, a fist is shown secured to each side of the mullion. A hanger system and bracing system extends from each fist and receives the upturned leg of the floor bracket. In other embodiments, a single fist may be provided with a single hanger system and bracing system. In still other embodiments, multiple floor brackets may be provided. For example, one floor bracket may be provided at or near the top surface of the floor and another may be provided at or near the bottom surface of the floor. In these embodiments, four engagement systems may be provided. Floor brackets or other structural interfaces may be provided throughout the thickness of the floor and any number of engagement systems can be used.
As another example of a modification within the scope of the invention, the damping device may be constructed of alternative materials. For example, in one embodiment, the damping device is made of a “crushable” material such as sand, stone, plaster board. cement board or other appropriate material that could absorb a blast. A device made of such crushable material may be constructed as a replaceable insert for the system.
The embodiments disclosed, or variations or modifications thereof can be advantageous for several reasons. Particularly, damping, in lieu of, or in addition to strengthening, reduces the affect of the forces on the curtainwall and the building. As such, costs associated with reinforcing the curtainwall can be reduced while the safety of the structure can be maintained. To better explain this advantage, two exemplary models may be described.
Referring to FIGS. 12-15, a comparative model analysis of two curtainwall systems with differing support stiffnesses is shown. In one curtainwall system, the support stiffness is assumed to be rigid or approximately 500 kips/inch. This system reflects an anchor system similar to that which has been described above, but without any damping pads, ductility features, or other damping devices, systems, or elements. In the other curtainwall system, the support stiffness is assumed to be flexible or approximately 10 kips/inch. This system reflects an anchor system as described above. Both of the curtainwall systems were then assumed to otherwise be the same. That is, the following assumptions were made:
Span=12′6″
Unit Width=5′0″
Impulse Pressure=6.5 psi
Impulse Duration=14 milliseconds
Allowable Ductility Factor=3
Allowable Rotation=3°
Section Profile=Rectangular H10″×W3″×T1/4″
Material=Aluminum 6061-T6 fy=35 ksi, fu=58 ksi
Wind Load=50 psf dmax=span/175
Based on these assumptions remaining constant between each of the curtainwall systems and only the support stiffnesses differing, the two systems were compared. As shown in FIG. 12, the magnitude of the displacement of the mullion exceeds 1 inch in the rigid support condition as compared to approximately ½ inch for the flexible support condition. Moreover, the dissipation of the rigid support condition is minimal as evidenced by the magnitude of the displacement of the mullion reducing to approximately ½ inch and remaining there for an extended period of time. Comparatively, in the flexible support condition, the magnitude is reduced much quicker from ½ inch to approximately 0 in a period of 0.15 seconds. Accordingly, the initial deflection of mullion with a flexible support is less than approximately 50% of the deflection of a mullion with a rigid support thereby significantly reducing the effect of a blast force on the curtainwall unit and the building structure. In addition, once the blast occurs, the vibration of the system is dissipated much faster with the flexible support system thereby reducing damage due to lingering or ongoing vibration.
Similarly as shown in FIG. 13, the mullion with the rigid support approaches a bending stress of 60 ksi, while the mullion with the flexible support sees a bending stress of approximately 30 ksi. Moreover, like the displacement diagram, the bending stress due to lingering vibration reduces to 0 ksi much faster in the flexible support condition than in the rigid support condition. Hysteresis diagrams in FIGS. 14 and 15 show the oscillating relationship between stress and strain of the mullions. As can be seen, FIG. 14 shows the hysteresis behavior of a rigidly supported mullion and FIG. 15 shows the hysteresis behavior of a flexibly supported mullion. The results shown in FIGS. 14 and 15 reflect similar results as those shown in FIGS. 12 and 13. That is, the flexibly supported mullion experiences less stress and less strain and the effects of the blast are dissipated much faster.
Referring to FIGS. 16 and 17, a comparative model analysis of two curtainwall systems with differing mullions is shown. In one curtainwall system, the curtainwall mullion depth is assumed to 7 inches and in the other system, the mullion depth is assumed to be 10 inches. Otherwise, both of the curtainwall systems were assumed to be the same. The following assumptions were made for each system:
Span=12′6″
Unit Width=5′0″
Impulse Pressure=6.5 psi
Impulse Duration=14 milliseconds
Allowable Ductility Factor=3
Allowable Rotation=3°
Section Profile=Rectangular H10″×W3″×T1/4″
Rectangular H7″×W3″×T1/4″
Material=Aluminum 6061-T6 fy=35 ksi, fu=58 ksi
Wind Load=50 psf dmax=span/175
Support Stiffness=10 kips/inch for flexible support.
As shown in FIGS. 16 and 17, the displacement of the 7″ mullion approached approximately 2 inches, while the displacement of the 10″ mullion approached ½ inch. The stress in the 7″ mullion exceeded 45 ksi, while the stress in the 10″ mullion was approximately 30 ksi. Accordingly, depending on tolerances of a given structure and the strength of materials available, an optimum section profile may be a 10″ deep mullion.
One having ordinary skill in the art should appreciate that there are numerous types, shapes, and sizes of cladding for which there can be a need or desire to damp blast loads according to an exemplary embodiment of the present invention. Additionally, one having ordinary skill in the art will appreciate that although the preferred embodiments illustrated herein reflect a generally flat and rectangular damping pad and generally slotted ductility features, these elements can have a variety of shapes and sizes.
All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, outboard, inboard, outer, inner, clockwise, and counterclockwise) are only used for identification purposes to aid the reader's understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary.
In addition, the term “about” or “approximately” should generally be understood to refer to both the corresponding number and a range of numbers. In addition, all numerical ranges herein should be understood to include each whole integer or fraction thereof within the range. The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the invention as claimed below. Although various embodiments of the invention as claimed have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. Other embodiments are therefore contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.

Claims

1. A blast resistant cladding, comprising:

a curtainwall coupled to a structure by an anchor system and defining a load path for transferring loads imparted on the curtainwall to the structure; and

an absorbing system positioned along the load path to absorb blast-type loads imparted on the curtainwall.

2. The cladding of claim 1 wherein the absorbing system comprises a normal force-type device to absorb and damp the forces through compression and tension.

3. The cladding of claim 2, wherein the absorbing system comprises a damping pad positioned between a pair of distribution elements, the distribution elements including damping surfaces and each surface of the distribution element coupled to a corresponding surface of the anchor system.

4. The cladding of claim 3, wherein the damping surfaces of the distribution elements are planar and the corresponding surface of the anchor system is planar.

5. The cladding of claim 1, wherein the absorbing system comprises a shear force-type device to absorb and damp the forces through shear deformation.

6. The cladding of claim 5, wherein the absorbing system comprises a damping pad positioned between a pair of distribution elements, the distribution elements including damping surfaces and each damping surface of the distribution element coupled to a corresponding surface of the anchor system.

7. The cladding of claim 6, wherein the damping surfaces of the distribution elements are planar and the corresponding surface of the anchor system is planar.

8. The cladding of claim 6, wherein the damping pad includes a plurality of damping layers, each layer separated by warp resisting elements.

9. The cladding of claim 1, wherein the absorbing system comprises a ductility feature to dissipate forces through ductile deformation.

10. The cladding of claim 9, wherein the ductility feature comprises a perforation positioned near an edge of the absorbing system to allow the edge to fail in a ductile manner under loading.

11. A system for supporting exterior cladding on a structure and resisting blast forces imparted thereon, the system comprising:

a cladding interface for fixedly engaging the cladding;

a structure interface for fixedly engaging the structure; and

an engagement system positioned between the cladding interface and structure interface, comprising:

a hanger system for vertically supporting the cladding; and

a bracing system for laterally supporting the cladding, the bracing system having an absorbing system for absorbing the blast forces.

12. The system of claim 11, wherein the absorbing system comprises a damping pad positioned between two opposing distribution elements, the distribution elements including damping surfaces and each damping surface of the distribution element coupled to a corresponding surface of the bracing system.

13. The system of claim 12 wherein the surfaces of the distribution elements are planar and the surface of the bracing system is planar.

14. The system of claim 12, wherein each damping surface of the distribution element is in a plane generally adjacent to and parallel to a plane defined by a corresponding surface of the bracing system.

15. The system of claim 12, wherein the bracing system is a shear force-type system.

16. The system of claim 15, wherein the damping pad is oriented generally orthogonally to an exterior surface of the cladding.

17. The system of claim 16, wherein the damping pad comprises two damping layers positioned between the distribution elements with a warp resisting element positioned between the two damping layers.

18. The system of claim 16, wherein the damping pad comprises three damping layers with two warp resistant elements positioned therebetween.

19. The system of claim 11, wherein the bracing system is a normal force-type system.

20. The system of claim 19, wherein the damping pad is oriented generally parallel to an exterior surface of the cladding.

21. The system of claim 11, wherein the absorbing system is a ductile failure-type system.

22. The system of claim 21, wherein the absorbing system comprises a ductility feature.

23. The system of claim 22, wherein the ductility feature includes a plurality of slots separated by ductile partitions and the slots fail in a ductile manner.

24. The system of claim 23, wherein the plurality of slots are arranged in a chevron pattern, the chevron pattern comprising two legs.

25. The system of claim 24, wherein the ductility feature includes a circular perforation arranged in the gap between the legs of the chevron pattern.

26. The system of claim 23, wherein the plurality of slots are arranged adjacent to one another.

27. The system of claim 22, wherein the ductility feature includes at least one circular perforation.

28. A blast resistant cladding, comprising:

a curtainwall arranged on a structure and defining a load path for transferring blast-type loads imparted on the curtainwall to the structure; and

a means for absorbing blast-type loads imparted on the curtainwall.