SEISMIC EVALUATIO OF STRUCTURAL I SULATED PA ELS

Transcription

1 AMERICA SOCIETY OF CIVI E GI EERS Internatıonal Commıttee, os Angeles Sectıon 5 th International Engineering and Constrction Conference (IECC 5), Agst 7-9, 8 SEISMIC EVAUATIO OF STRUCTURA I SUATED PA ES Khalid M. Mosalam, Joseph Hagerman and Henry Kelly Professor and Vice Chair, Department of Civil and Environmental Engineering, University of California, Berkeley, CA 947-7, mosalam@ce.berkeley.edy Project Director, Bilding Technology, Federation of American Scientists (FAS), Washington, DC 6 President, Federation of American Scientists (FAS), Washington, DC 6 Abstract New constrction represents a significant portion of the total energy consmed by the bilding sector. One approach for redcing the energy impact of new constrction is to tilize composite materials. Strctral inslated panels (SIPs) are stressed-skin panels composed of an energy-efficient core sch as expanded polystyrene (EPS) paired with either traditional or novel facing materials inclding plywood, oriented strandboard (OSB), cement mortar, or steel. Crrently SIPs are ndertilized in residential constrction, which instead predominantly employs timber-framing methods inclding sheathed timber shear walls. While the seismic performance of the latter has been extensively stdied and incorporated into bilding codes, there is considerably less information available abot the general behavior of SIPs, especially regarding their behavior when sbjected to seismic loads. This paper focses on the characterization of the mechanical properties and seismic performance of SIPs sing experimental techniqes. Specimens stdied inclde both OSBfaced and cementitios SIPs, where panels were tested withot panel-to-panel connections. Keywords: Diagonal tension test, Energy efficiency, Psedo-dynamic test, Qasi-static test, Seismic resistance, Strctral inslated panels. Introdction With the rise of indstrial nations and developing contries alike comes a demand for hosing and infrastrctre, which rely on the availability of natral resorces. As poplations swell, the limitations of crrent development practices come sharply into focs: approximately % of the world s poplation residing in Western Erope, North

2 America and Japan, are consming almost 8% of the total available energy and resorces in order to maintain a high standard of living (Mehta, 999). New constrction represents a significant portion of this total energy consmed, with constrction in developed contries dominated primarily by the se of steel, concrete, and timber. Noting that the concrete and Portland cement indstries are two of the largest consmers of natral resorces, sch as water, sand, gravel, and crshed rock, it is imperative to find alternatives to energyintensive materials and constrction. One approach for redcing the energy impact of new constrction is to design strctres with composite materials, allowing each component of the composite to be sed in smaller amonts in a more efficient manner. Composite constrction tilizing steel and concrete is widely practiced in the design of large strctres, althogh a variety of strctral systems are available for smaller applications sch as residential and light-commercial edifices. Strctral inslated panels (SIPs) are one example of a small-scale strctral system, and are a type of stressed-skin panel, composed of an energy-efficient core sch as expanded polystyrene (EPS) with both traditional and novel facing materials sch as plywood, oriented strandboard (OSB), cement mortar, or steel. Crrently, residential constrction predominantly tilizes timber-framing, inclding sheathed timber shear walls, which have been extensively stdied and incorporated into bilding codes and other design docments. Mch of this existing work considers the strctral behavior in light of monotonic and cyclic testing (He et al., 999). Dynamic-related work (Drham et al., ) also exists, bt is smaller in nmber. There is considerably less information available abot the behavior of SIPs, especially as pertains to their behavior in seismic regions. Developed over 5 years ago, SIPs are extensively sed throghot Erope and North America. Their application in seismically hazardos regions is limited de to nacceptable performance as demonstrated by cyclic testing. While there is a growing database of research pertaining to SIPs, none has attempted to sbject the panels to more realistic dynamic loading regimes. As sch, this research s long term goals focs on the characterization of the dynamics response of SIPs. engthy strides can be made in seismic design approaches and codes in order to permit widespread se of this potentially sstainable material. Backgrond In low-rise wood strctres sch as residences, the primary lateral load-carrying system is a timber shear wall, consisting of framing members sheathed most commonly with plywood or OSB, althogh non-timber alternatives are also available. According to (van de indt, 4), wood shear walls are capable of dissipating large amonts of energy throgh their nonlinear behavior at low forces, attribted mostly to the fastener deformations. Another attribte that makes timber shear walls appealing is their low seismic mass, de to a high strength and stiffness to weight ratio. A considerable disadvantage of traditional timber shear walls is the tendency for an energy inefficient strctre. Typically inslated with fiber fill, the framing elements provide a break in the thermal bondary. A stdy in (Choi, 7) investigated an alternative method of inslating timber shear walls. By incorporating

3 a layer of fly ash, with and withot fiber-reinforcement, prior to inslating and dry-walling, it was fond that the thermal efficiency cold be improved. SIPs are the basis for an energy efficient means of constrcting residential and light commercial bildings. Mechanically, SIPs carry loads in a fashion similar to I-beam shapes: the wood sheathing is analogos to the flanges of the beam, carrying a majority of the moment, while the foam core behaves like the shear-carrying web, refer to Figre a. An efficient section is obtained when the weight of the core is roghly eqal to the combined weight of the sheathing faces (Allen, 969). Fnctionally speaking, the core mst be stiff enogh perpendiclar to the faces to ensre that the faces remain separated by a constant distance. Additionally, the foam mst be stiff enogh in shear to prevent sliding of the faces, which wold reslt in behavior similar to two independent beams rather than a composite nit. The interface between the foam core and the wood sheathing consists of a layer of adhesive to mainly prevent relative movements of the faces and the core. Typically, three types of splines are tilized for SIPs panel-to-panel connections: solid pieces of lmber; srface splines consisting of 4-inch strips of OSB (Figre b); and foam block splines. Becase foam block and srface splines do not reslt in a thermal break, they are preferred over the solid lmber connections. In locations sbjected to point loads, a solid lmber spline is sed to create a dobled std, strong enogh to spport the concentrated load. Rigid Foam Inslation Strctral Adhesive Strctral Skins a) Components b) Srface spline connection Figre (): SIPs components and example panel-to-panel connection ["=5.4 mm] Jamison (997) provided one of the earliest stdies of the racking performance of SIPs, specifically comparing this performance to existing knowledge on the behavior of timber shear walls. Monotonic and cyclic tests were performed, reslting in a primary mode of failre for the SIPs shear walls at the bottom plate, except in the presence of tie-down anchors, which shifted the mechanism of failre away from the bottom of the wall. The cyclic testing procedre followed the seqential phased displacement (SPD) procedre, which consists of an initial cycle followed by stabilized cycles for each amplitde phase. Use of stabilized cycles attempted to indce behavior representative of that characterized by repetitive cyclic loading, e.g. de to earthqake loads, reslting in fatige of drywall screws from nmeros loading cycles.

4 Experimental testing of strctral systems is vital not only for research and development of new prodcts, bt also for gathering information abot the dynamic performance of existing technologies. Crrently, when knowledge abot the seismic capacity of a strctre or strctral component is desired, there are three approaches to obtain this information experimentally: qasi-static tests, shaking table tests, and psedo-dynamic tests. Qasistatic tests are condcted at a loading rate sfficiently slow sch that strain-rate effects are negligible. Therefore, both monotonic and cyclic tests can be categorized as qasi-static, and many material testing standards, inclding those of ASTM, are qasi-static. While these tests are the simplest tests to perform and remove some of the variability associated with experimental procedres, they are also the most limited in the seflness of the information that they can provide abot the tre dynamic behavior of test specimens. Psedo-dynamic tests, first developed in the 97s, have gained momentm over the last years in the strctral engineering commnity becase of their wide applicability and contining refinements on the part of the academic commnity. The power of psedodynamic (or hybrid simlation) lies in its ability to physically model strctral components that are not well-nderstood while modeling well-nderstood components nmerically. The analytical sbstrctre sally consists of a nmerical model of the governing eqations of motion nder dynamic excitation, which are solved dring the test to determine displacements or forces to be applied in the physical sbstrctre in displacement or force control (Elkhoraibi and Mosalam, 7). However, for large strctres, e.g. mlti-story bilding, where nonlinearity is only expected in few strctral elements of the lower story while the rest of the elements and the pper stories remain elastic, this comptational model can be extended. For example, the experimental model here focses on few elements of the lower story, while the nmerical model wold simlate the rest of the bilding. This is where the power of hybrid simlation resides as it can isolate sbstrctres and stdy the behavior withot the need for physical models of the entire strctre, as in the more costly and size limiting shaking table tests (Elkhoraibi and Mosalam, 7). Introdction of psedo-dynamic methodology to the stdy of SIPs cold allow for improved nderstanding of the behavior of these elements dring seismic loading. Firstly, the testing of SIPs has only been performed in the context of individal panels. While panel interaction has been stdied to a limited degree in terms of panel-to-panel and panel-todiaphragm interaction, there is no existing comprehensive stdy of a fll-scale strctre composed entirely of SIPs. Hybrid simlation, throgh mathematical description of adjacent elements, cold allow for the stdy of SIPs in larger, more complex assemblages. Secondly, cyclic protocols sch as those developed in (Krawinkler et al., ) were originally defined for wood frame strctres, and its extension to panel strctres may not be appropriate or immediately jstifiable. astly, it is important to define seismic performance in terms of response to realistic seismic loading histories. Material Tests Cementitios SIPs (CSIPs) composed of fiber-cement mortar facings with EPS core together with traditional SIPs were the sbject of diagonal tension tests (ASTM, 988) sed

5 for the evalation of shear behavior, Figre. The CSIPs were provided by Mississippi Strctral Inslated Panel Systems. Each panel consisted of two 7/6" ( mm) fibercement mortar facings with EPS core.7" (94 mm) thick, for an overall thickness of 4.575" (6 mm). The core material has a nominal density of. pcf (6 kg/m ), and the panels are rated with an R -vale of 5 for walls. Aside from the brittle behavior of the fibercement mortar facings, the polyrethane adhesive between the core and facings also behaves in a brittle fashion. The panels were ' wide by ' tall and were loaded monotonically with an average target rate of kips/sec according to ASTM E59 (988). Figre (): Material test setp and instrmentation of CSIP The shear force pre nit length of the wall thickness t is defined as: V t = P ( t ) () where P is the applied load. The wall s drift ratio, δ, is calclated as illstrated in Figre. In the following, the exact expression in Figre is sed where is the wall side length and is the wall diagonal shortening in the vertical direction. Exact: = Approximate: = ( ) = ( ) ( ) δ = ( ) ( ) ( ) = ( ) ( )( + ) ( ) ( ) ( ) ( ) = = δ = = = δ () Figre (): Calclation of the panel drift ratio in diagonal tension tests ()

6 Focsing on the peak shear force per nit thickness and the corresponding drift ratio, a complete smmary of reslts is given in Table. In this table, the qantities with sbscript r refer to the residal (after large peak force drop) vales. Consistency in the definition of these residal qantities was maintained in every grop of tests by adopting three definitions: δ r =.49% for the two CSIPs (CSIP and CSIP) tested dry, δ r =.% for the three SIPs tested with OSB facing (dry, moist, and wet), and δ r =.6% for the three other CSIPs (dry, moist, and wet). It is noted that CSIPs experienced sdden drop in the capacity, qantified by the drop ratio in the last colmn of Table, while the capacity of SIPs with OSB facing drops more gradally. Also, the water exposre of SIPs leads to redctions in the strength and the drop ratio (i.e. more dctile behavior). On the other hand, water exposre of CSIPs leads to nclear trend de to inherent variability in the tested panels and frther tests with more samples is recommended to nderstand this phenomenon in CSIPs and to accont for the strength redction de to water absorption as recognized in ASTM. Table (): Peak reslts from material tests of CSIPs and SIPs Specimen V t [kip/in]δ [%]( V t) r [kip/in] δ r [%] ( t) V r [%] V t CSIP CSIP SIP OSB-Dry SIP OSB-Moist SIP OSB-Wet CSIP-Dry CSIP-Moist CSIP-Wet Racking Test Procedres Five SIPs consisting of OSB sheathing and EPS inslating foam were sbjected to cyclic and psedo-dynamic testing regimes to assess their behavior nder seismic loads. Panels were tested individally, withot panel-to-panel connections, Figre 4. The SIPs were fabricated by Premier Bilding Systems, Dixon, CA. With an overall panel thickness of 4- /8" ( mm), the panels consisted of two 7/6" ( mm) OSB skins with a -/" (89 mm) thick EPS foam core, Figre 5. While panels may be prodced in widths ranging from 4' to 4', the provided SIPs were 4' wide by 8' high. These OSB skins are classified as Strctral, Exposre wood sheathing complying with DOC-PS- (ICC ES, 4). The EPS core has a nominal density of. pcf (6 kg/m ) and is viewed as a closed-cell material bt it absorbs water to -5% of its weight fiberglass is an example of an opencell material. The EPS is a non-toxic hydrocarbon; its combstion prodces water vapor, carbon dioxide, and trace levels of ash. The foam core is joined to the OSB skins with a strctral grade Type II, Class laminating adhesive meeting APA AFG- specifications (ICC ES, 4), i.e. this adhesive is sitable for se in panels spporting loads other than panel self weight and has a high resistance to both moistre and creep.

7 Framing timber, sch as the end plates, consisted of nominal 4 (-/" -/" (8 mm 89 mm) actal dimensions) ntreated Doglas-fir strctral grade lmber. These elements were installed at the top and bottom of each panel in pre-ct channels. Fasteners were common bright nails nails with a normal srface finish in two sizes, 8d and 6d, along with -5/8" coarse thread drywall screws. " 8 " X4 Top Plate Fasteners, 6" o.c. (typ.) OSB Facing Foam Core 7 6 " " 7 6 " OSB Facing 48" 4X4 SIP Fasteners, 6" o.c. (typ.) X4 Top Plate " 8 " Figre (4): Panel Configration for racking tests ["=5.4 mm] 8 " Figre (5): Typical SIP cross-section and test setp ["=5.4 mm] Monotonic Testing Procedre Monotonic tests performed consisted of a static one-directional ramp test, with rates of displacement ranging within.-.7 in/sec and varying from rn to another. Data was continosly recorded at a freqency of 64 samples per second. The monotonic tests were performed in preparation for the qasi-static cyclic tests as recommended by the CUREE- Caltech Woodframe Project (Krawinkler et al., ). Cyclic Testing Procedre As early as the 94s, standard racking tests were developed for calclating and predicting the shear strength of wood shear walls (van de indt, 4). Recommendations for cyclic tests evalating the performance of a complete wall configration are otlined in ASTM E- 564 (ASTM, 995). However, for the presented tests, the CUREE protocol (Krawinkler et al., ) was tilized. This loading seqence is intended for se with tests for which an identifiable deformation parameter relates the component response to the strctral system: considering the SIPs, the racking distortion can be directly related to story drift. The protocol serves as an evalation of capacity level seismic performance of components sbjected to ordinary (not near-falt) grond motions with % probability of exceedance in 5 years. This protocol is composed of initiation, primary, and trailing cycles based on a reference deformation,, defined as the maximm deformation expected. A monotonic

8 test was performed to determine m, which is the deformation at which the applied load first drops below 8% of the maximm sstained load. A fraction of m shold be sed as the reference deformation, with =. 6 m sggested. This redction acconts for cmlative damage incrred dring a cyclic test which reslts in discrepancies between the maximm deformations estimated from monotonic and cyclic tests. Data was recorded continosly dring the cyclic tests at a rate in the range -64 samples per second. Psedo-Dynamic Testing Procedre A single-degree-of-freedom (SDOF) is assmed to represent the comptational model of the tested SIP within the framework of psedo-dynamic testing. The information assmed for this SDOF is based on a previos stdy condcted on a 94 s design of a two-story wood hose over garage (Elkhoraibi and Mosalam, 7). The eqivalent inertia mass of.65 kip-sec /in of the SDOF was taken as that of the test bilding. Mass proportional damping was selected with 5% damping ratio. The sed time histories for exciting the SDOF model were spectrally matched to the falt normal (FN) and falt parallel (FP) spectra for the design basis earthqake (DBE) and the pper-bond earthqake (UBE), i.e. those with % probability of exceedance in 5 and years, respectively. The records from oma Prieta, CA, 989 earthqake, os Gatos station, were adopted assming a stiff soil site. Three levels of shaking were applied as listed in Table. Table (): Grond motion levels for the psedo-dynamic tests on SIPs [ in=5.4 mm] evel Scale Description Acc. [g] Vel. [in/sec] Displ. [in] I.5 UBE Elastic (FP only) II. DBE DBE (FP only) III. UBE UBE (FP then FN long dration) Reslts and Discssion Test reslts are presented for monotonic and cyclic tests condcted on Specimens,, and separate from those of the psedo-dynamic tests condcted on Specimens 4 and 5. Monotonic and Cyclic Tests Specimen was tested as a preliminary investigation of the cyclic behavior of SIPs. Before a fll cyclic regime was applied, a nmber of smaller calibration motions were applied to ensre that the instrmentation and data acqisition system were operating properly. A peak load of.9 kip was carried by the panel at.98" of displacement as listed in Table. Using information from Specimen, the testing of Specimen represents a more refined approach, incorporating the procedres otlined in the CUREE protocol (Krawinkler et al., ). From this monotonic data, the reference displacement of." was calclated. A single cyclic seqence was applied to the specimen. The overall maximm load of.77 kip carried by Specimen occrred dring earlier monotonic testing. Dring the cyclic rn, the

9 maximm load was. kip at.88", which highlights the fact that the panel experienced significant damage dring the monotonic rns, Table, as shown by the asymmetric response with significantly different peak loads and corresponding displacements. Bilding on the lessons learned from testing Specimen, the same deformation of." was sed as a reference vale for designing the cyclic protocol for Specimen. In this case, the specimen was not sbjected to monotonic rns prior to the cyclic test in order to gain insight into the behavior of an nscathed specimen. In this case, the peak force of.6 kip occrred at a deformation of.99", Table. Small amonts of damage may have been incrred when this specimen was sbjected to a small nmber of initial low-level cycles. Figre 6 presents the load-displacement relationship for Specimen. Table (): Maximm and minimm loads, cyclic series [ kip=4.45 kn, in=5.4 mm] Maximm Minimm Specimen oad Displ. [in] oad Displ. [in] Force, kips - - Specimen, Rn Displacement, inches 4 6 Figre (6): oad-displacement relationship of Specimen [ kip=4.45 kn, in=5.4 mm] When evalating the relative performance of specimens, it is sefl to consider the effect of loading rate. Specimen was loaded manally with loading rate varying between approximately in the range - in/sec within the cycles. The loading rate for Specimen varied in the range.-.9 in/sec, bt the specimen was loaded sch that the time reqired to complete one fll cycle was constant at sec/cycle. In contrast, Specimen experienced a constant loading rate of approximately.5 in/sec, with the time for completion of a fll cycle varying in the range 4-5 sec/cycle. For both Specimens and, the loading seqence was atomated, in trn providing more reglar intervals between cyclic series. The differences in performance of the three specimens can therefore be attribted to a combination of factors, primarily the loading rate, nmber of cycles, and the presence of initial damage to the specimen de to initial monotonic loading.

10 In order to change the behavior from a rigid-body rotation to a racking motion, the se of tie-down anchors has proven sccessfl (Jamison, 997). From the tests performed by Jamison (997), it was also fond that the addition of a second base plate is ineffective in moving the failre mechanism away from the base connection. Schmidt et al. (994) determined that plift shold be prevented by se of proper anchorage via anchor bolts, as plift largely contribtes to lateral wall displacement. Significant plift was observed throghot the cyclic tests for all specimens, and shold be minimized in ftre tests. Failres of all specimens occrred simltaneosly along the bottom and top plates of the wall at the connections. Once a nmber of nails had failed, the wall appeared to rock nder rigid body rotation abot the center line of the wall. When drywall screws were sed in Specimen, it was observed that they failed in a highly brittle manner. The nailed connections in Specimens and were slightly more resilient, and cold be re-hammered in order to regain some of their fnction after they started to fail via pll-ot. In general, failre was best characterized by OSB splitting at the connection points, nail pll-throgh or pll-ot, and foam crshing as shown in Figre 7 for Specimen. With the connections broken, the rigidly rotating wall crshes the foam at either end of the panel, as observed in Figre 8 for Specimen. These observations are what wold be expected, as experimental tests by Cheng et al. (988) highlighted the sheathing-to-framing connection as the point of failre, while Stewart et al. (988) described nail failres, inclding fractring of the sheathing nail heads and withdrawal of nail shanks from the framing. a) Overview of bottom part b) Detailed top and bottom connections Figre (7): Failre in Specimen Figre (8): EPS core crshing in Specimen

11 Psedo-dynamic Tests Specimens 4 and 5 were tested psedo-dynamically sing the procedres discssed previosly and tilizing the grond motions levels listed in Table. After levels I and II of earthqake loading, nails were re-hammered to bring capacities back to its original vales before application of level III earthqake, Table. Both specimens were tested identically for the repeatability of the reslts, which is confirmed from the comparisons in Figre 9. Therefore, vales below are average reslts from positive excrsions of Specimens 4 and 5. evel I (corresponding to 5% UBE) corresponded to almost elastic response with some energy dissipation throgh hysteresis and slight pinching response cased by the fasteners (nails) deformation. At this level, the overall peak load of abot.65 kip was reached at approximately.44" displacement. Increasing earthqake level to % DBE (level II) reslts in larger energy dissipation and prononced pinching response with peak load of abot.57 kip at approximately.4" displacement. Finally, level III (% UBE) corresponded to loss of shear strength where the load-displacement relationship in positive excrsions experienced softening dring the strong motion interval. For this level, the peak load was abot.59 kip corresponding to approximately.8" lateral displacement. Adopting a definition of ltimate deformation to correspond to % redction of the lateral load, at 8% of the peak load, the ltimate displacement was.8". Assming the end of the elastic response corresponded to the peak of level I (this is also confirmed by the response to level II), the ltimate displacement dctility can be defined as.8/.44=4.4. Conclding Remarks The paper presented test reslts for material characterization of SIPs and CSIPs sbjected to shear stresses. Racking test reslts of SIPs sing qasi-static and psedo-dynamic techniqes represented the main part of the paper. The reslts confirmed the validity of psedo-dynamic testing to characterize the SIPs seismic performance with less sensitivity to test parameters than qasi-static testing. Preliminary conclsions inclde reasonable energy dissipation and ltimate displacement dctility slightly above 4. for SIPs withot panel-to-panel connections. SIP strength was maintained p to and inclding % of the design basis earthqake (DBE) % probability of exceedance in 5 years. Moreover, significant redction of strength with large energy dissipation was observed for a longer dration pper-bond earthqake (UBE) % probability of exceedance in years. For ftre investigation, one may sggest the following improvements: A thorogh investigation of the development of common connection types wold be beneficial, as this is the most likely point of failre in SIPs and CSIPs. Both panel-topanel and panel-to-diaphragm connections shold be considered. Of special importance is the fnction of the adhesive within the connections, and whether its se represents any improvements of the performance. Developing copled comptational tools for SIPs and CSIPs to accont for thermal and strctral behavior can advance this research beyond the realm of strctral engineering to treat SIPs and CSIPs designs in the context of optimization problems.

12 From sstainability point of view and de to increased environmental awareness, lifecycle analysis and assessment of SIPs and CSIPs is an important task. Displacement [mm] Displacement [mm] Force [kn] 5 Force [kn] Displacement [mm] evel I Displacement [mm] Force [kn] 5 Force [kn] Displacement [mm] evel II Displacement [mm] Force [kn] 5 Force [kn] evel III a) Specimen 4 b) Specimen 5 Figre (9): Similar psedo-dynamic test reslts from Specimens 4 and 5

13 ACK OWEDGEME T The first athor acknowledges the financial spport nder the Intra-University Transaction No. 685 from the UC Ernest Orlando awrence Berkeley National aboratory (BN) nder Contract No. DE-AC-5CH of the United States Department of Energy. The athors thank these individal for their technical help dring the experimental research: Patricia Decker, Shakhzod Takhirov, Sean Wade, and Matias Hbe. The experimental research was condcted in the mico-nees@berkeley laboratory of EERC. References. Mehta, P.K. (999). Concrete Technology for Sstainable Development: An Overview of Essential Principles, Vancover CANMET/ACI International Symposim on Concrete Technology for Sstainable Development, Dec. 4.. He, M., Magnsson, H., am, F. and Prion, H.G.. (999). Cyclic Performance of Perforated Wood Shear Walls With Oversize OSB Panels, Jornal of Strctral Engineering, ASCE, Volme 5, Isse, pp Drham, J., am, F. and Prion, H.G.. (). Seismic Resistance of Wood Shear Walls With arge OSB Panels, Jornal of Strctral Engineering, ASCE, Volme 7, Isse, pp van de indt, J.W. (4). Evoltion of Wood Shear Wall Testing, Modeling, and Reliability Analysis: Bibliography, ASCE, Practice Periodical on Strctral Design and Constrction, Volme 9, Isse, pp Choi, C. (7). Application of Fly Ash as a ight-frame Wood Hose Inslator, Master s Thesis. CEE, Colorado State University. 6. Allen, H. G. (969). Analysis and Design of Strctral Sandwich Panels, Pergamon Press, Oxford. 7. Jamison, J.B. (997). Monotonic and Cyclic Performance of Strctrally Inslated Panel Shear Walls, M.S. Thesis, CE Virginia Tech, Blacksbrg, VA. 8. Elkhoraibi, T. and Mosalam, K.M. (7). Towards Error-Free Hybrid Simlation Using Mixed Variables, Earthqake Engineering and Strctral Dynamics, Volme 6, Isse, pp Krawinkler, H., Parisi, F., Ibarra,., Ayob, A. and Medina, R. (). Development of a Testing Protocol for Wood frame Strctres, CUREE Pblication No. W-, California.. International Code Concil (4). ICC ES egacy Report NER-6. March.. ASTM (988). ASTM E59-88 Standard Test Method for Diagonal Tension (Shear) in Masonry Assemblages, American Society for Testing Materials, Pennsylvania.. ASTM (995). ASTM E Standard Practices for Static oad Test for Shear Resistance of Framed Walls for Bildings, Annal Book of ASTM Standards, Schmidt, B.., Neilsen, M. and inderman, R. R. (994). arrow Plywood Shear Panels, Earthqake Spectra, Volme, Isse, pp Cheng, C.., Itani, R. Y. and Polensek, A. (988). Characteristics of Wood Diaphragms: Experimental and Parametric Stdies, Wood Fiber Science, Volme, Isse 4, pp Stewart, W. G., Dean, J. A. and Carr, A. J. (988). The Earthqake Behavior of Plywood Sheathed Shearwalls, Proceedings of the International Conference on Timber Engineering, pp