In this investigation, thirty-six shear walls measuring 8 feet (2.4 m) in width and possessing heights of 8, 9 and 10 feet (2.4, 2.7 and 3.0 m) were subjected to the reversed, cyclic loading schedule of the standard CUREE protocol in order to determine the performance capabilities of shear walls greater than 8 feet (2.4 m) in height sheathed with long panels. Of the thirty-six walls, a total of twelve walls measuring 9 and 10 feet (2.7 and 3.0 m) in height were sheathed with 4 x 8 feet (1.2 x 2.4 m) panels which required additional blocking members between the studs of the frame. Values obtained from the tests performed on these walls provided a direct comparison to those obtained from the walls of equal height, but sheathed with a long panel capable of spanning the entire height of the wall. The capabilities of long panels were investigated when used as the sheathing elements of shear walls with and without a mechanical hold-down device attached to the base of the end stud. An advantage of the long panel was investigated in which it was extended past the bottom plate and down onto the band joist to determine if significant resistance to the uplift present in walls without mechanical hold-down devices could be provided. Also, the effects of orienting the fibers of a 4 x 9 feet (1.2 x 2.7 m) panel in the alternate direction were examined. Average values of the parameters produced by walls sheathed with long panels either matched or exceeded those of its counterpart sheathed with 4 x 8 feet (1.2 x 2.4 m) panels in all configurations except the 10 feet (3.0 m) tall wall without hold-down devices. In fact, 4 x 9 feet (1.2 x 2.7 m) panels increased the performance of 9 feet (2.7 m) tall walls equipped with hold-down restraint significantly. Extending the long panels past the bottom plate and down onto the band joist improved the performance of both 8 and 9 feet (2.4 and 2.7 m) tall prescriptive shear walls significantly. Walls sheathed with panels made of fibers oriented in the alternate direction performed identically to those sheathed with panels of typical fiber orientation until the point of peak load. Once peak load was reached, walls sheathed with panels of alternate oriented fibers failed in a more sudden and brittle manner. / Master of Science

<p>Composite plate shear walls – concrete-filled (C-PSW/CF) are a new innovative lateral force resisting system intended for high-rise buildings. The walls consist of parallel steel faceplates connected with tie bars and filled with concrete. This dissertation introduces the C-PSW/CF </p> <p>system and coupled C-PSW/CFs consisting of C-PSW/CF walls and composite coupling beams. Three studies are presented herein covering seismic design parameters for C-PSW/CFs, non-linear modeling techniques for composite coupling beams, and the design philosophy for coupled C-PSW/CFs.</p> <p> </p> <p>The first study summarizes the results of a recent FEMA P695 study completed to verify seismic design parameters for uncoupled C-PSW/CFs with rectangular flange plate boundary elements. Seven archetype structures were: (i) designed, (ii) modeled using a benchmarked fiber-based finite element analysis approach, (iii) subjected to nonlinear pushover analysis, (iv) subjected to incremental nonlinear dynamic analysis to failure for 22-sets of scaled ground motions, and (v) the results were statistically analyzed to assess performance. These structures ranged from three (3) to twenty-two (22) stories and included both planar and C-shaped wall configurations. As part of this design process, recommendations for stiffness approximations for linear analysis of C-PSW/CFs</p> <p>were developed. Additionally, these nonlinear incremental dynamic analysis results were post-processed to determine the rotation and strain demands at the base of these structures at the design basis, maximum considered, and failure level earthquakes. These results showed that the rotation and strain demand at failure level earthquakes were comparable regardless of the ground motion. Ultimately, this FEMA P695 approach verified the R factor of 6.5, C_d factor of 5.5, and Ω₀ of 2.5 for C-PSW/CFs with boundary elements. </p> <p><br></p> <p>The second study proposes modeling approaches for composite coupling beams used in combination with C-PSW/CFs. Capturing the behavior of these components is critical to understanding the system behavior of coupled C-PSW/CFs, as the coupling beam components undergo yielding, plastification, and fracture prior to collapse of coupled C-PSW/CF walls. Although steel-concrete composite walls have been a known structural system for decades, only recently have coupled C-PSW/CF systems been investigated and implemented as a seismic force resisting system. As the interest in coupled C-PSW/CF systems increases, the necessity of reliable nonlinear modeling techniques for pushover, cyclic, and seismic analysis has become apparent. This paper presents fiber-based options for modeling composite coupling beam components of coupled C-PSW/CF walls for use in nonlinear and seismic response analyses. Recommendations include effective steel and concrete stress-strain curves, modeling parameters for fiber-based </p> <p>materials, and concentrated plasticity options for additional computational efficiency. These recommendations are then implemented for a full-scale coupling beam section. </p> <p><br></p> <p>In the final study, a capacity design principle is used to establish a basis for the seismic design of coupled composite plate shear walls – concrete filled (CC-PSW/CF) systems. This design philosophy implements a strong wall-weak coupling beam approach, where flexural yielding in coupling beams occurs before flexural yielding at the base of walls. The coupling beams are sized </p> <p>to resist the calculated seismic lateral force level. The walls are sized to resist an amplified seismic lateral force corresponding to the overall plastic mechanism for the structure, while accounting for the capacity-limited forces from the coupling beams and the coupling action between the walls. Based on this philosophy, recommendations and requirements for appropriate sizing of coupling beams and C-PSW/CFs are presented. These recommendations are used to design four example (8-22 story) structures and evaluate their seismic behavior. The structures were modeled using 2D finite element models and fiber-based models subjected to monotonic and time history analysis. </p> <p>The nonlinear inelastic behavior and seismic responses of the example structures were in accordance with the capacity limited design philosophy (strong wall-weak beam), thus confirming the philosophy’s  efficacy. </p>

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: In regions of moderate seismicity it has been shown that a suitable structural system is created when designing the shear wall with a plastic hinge zone at the lower part of the wall, with the shear walls resisting lateral loads and all other structural elements designed to resist gravity loads. A suitably stiff foundation is required for the assumption of plastic hinge zones to hold true. This foundation should have limited rotation and should remain elastic when lateral loads are applied to the structure. Ensuring a foundation with a greater capacity than the shear wall results in excessively large shear wall foundations being required in areas of moderate seismicity for buildings with no basement level. This study aims to investigate the feasibility of reducing the size of shear wall foundations in areas of moderate seismicity for buildings with no basement level. The investigation is aimed at allowing shear wall foundation rocking and taking into account the contribution of structural frames to the lateral stiffness of the structure. An example building was chosen to investigate this possibility. Firstly, lateral force-displacement capacities were determined for a shear wall and an internal reinforced concrete frame of this investigated building. Nonlinear momentrotation behaviour was determined for the wall foundation size that would traditionally be required as well as for six other smaller foundations. The above capacity curves against lateral loads were then used to compile a simplified model of the structural systems assumed to contribute to the lateral stiffness of the building. This simplified model therefore combined the effect of the shear wall, internal frame and wall foundation. Nonlinear time-history analyses were performed on this simplified model to investigate the dynamic response of the structure with different wall foundation sizes. By assessing response results on a global and local scale, it was observed that significantly smaller shear wall foundations are possible when allowing foundation rocking and taking into account the contribution of other structural elements to the lateral stiffness of the building. / AFRIKAANSE OPSOMMING: Daar is reeds getoon dat ʼn voldoende strukturele sisteem verkry word in gebiede van gematigde seismiese risiko indien ʼn skuifmuur ontwerp word met ʼn plastiese skarnier sone naby die ondersteuning van die muur. Skuifmure word dan ontwerp om weerstand te bied teen laterale kragte met alle ander strukturele elemente ontwerp om gravitasie kragte te weerstaan. Vir die aanname van plastiese skarnier sones om geldig te wees word ʼn fondasie met voldoende styfheid benodig. Só ʼn fondasie moet beperkte rotasie toelaat en moet elasties bly wanneer laterale kragte aan die struktuur aangewend word. ʼn Fondasie met ʼn groter kapasiteit as dié van die skuifmuur lei daartoe dat uitermate groot fondasies benodig word in gebiede van gematigde seismiese risiko vir geboue met geen kelder vlak. Hierdie studie is daarop gemik om die moontlikheid van kleiner skuifmuur fondasies te ondersoek vir geboue met geen kelder vlak in gebiede van gematigde seismiese risiko. Die ondersoek het ten doel om skuifmuur fondasie wieg aksie toe te laat en die bydrae van strukturele rame tot die laterale styfheid van die struktuur in ag te neem. Eerstens is die laterale krag-verplasing kapasiteit van ʼn skuifmuur en ʼn interne gewapende beton raam van die gekose gebou bepaal. Nie-lineêre moment-rotasie gedrag is bepaal vir die skuifmuur fondasie grootte wat tradisioneel benodig sou word asook vir ses ander kleiner fondasie grotes. Die bogenoemde kapasiteit kurwes is gebruik om ʼn vereenvoudigde model van die strukturele sisteme wat aanvaar word om laterale styfheid tot die gebou te verleen, op te stel. Hierdie vereenvoudigde model kombineer gevolglik die effek van die skuifmuur, interne raam en skuifmuur fondasie. Nie-lineêre tydgeskiedenis analises is uitgevoer op die vereenvoudigde model ten einde die dinamiese reaksie van die struktuur te ondersoek vir verskillende fondasie grotes. Resultate is beoordeel op ʼn globale en lokale vlak. Daar is waargeneem dat aansienlik kleiner skuifmuur fondasies moontlik is deur wieg aksie van die fondasie toe te laat en die bydrae van ander strukturele elemente tot die laterale styfheid van die gebou in ag te neem.

This thesis presents experiments and numerical analysis of a novel cold-formed steel framed shear wall sheathed with corrugated steel sheets. The objective of this newly designed shear wall is to meet the growing demand of mid-rise buildings and the combustibility requirement in the International Building Code. The strength of the novel shear wall is higher than currently code certified shear wall in AISI S400-15 so that it could be more favorable for mid-rise building in areas that are prone to earthquakes and hurricanes. Full-scale monotonic and cyclic tests were conducted on bearing walls and shear walls under combined lateral and gravity loads. Though the gravity loads had negative effects on the strength and stiffness of the shear wall due to the buckling of the chord framing members, it still shows promise to be used in mid-rise buildings. The objective of numerical analysis is to quantify the seismic performance factors of the newly design shear wall lateral-force resisting system by using the recommended methodology in FEMA P695. Two groups of building archetypes, story varied from two to five, were simulated in OpenSees program. Nonlinear static and dynamic analysis were performed in both horizontal directions of each building archetype. Finally, the results of the performance evaluation verified the seismic performance factors(R=Cd=6.5 and Ω =3.0) were appropriate for the novel shear wall system.

An analytical model for lateral deflection in cold-formed steel shear walls sheathed with steel is developed in this research. The model is based on the four factors: fastener displacement, steel sheet deformation, and hold-down deformation, which are from the effective strip concept and a complexity factor, which accounts for the additional influential factors not considered in the previous three terms. The model uses design equations based on the actual material and mechanical properties of the shear wall. Furthermore, the model accounts for aggressive and conservative designers by predicting deflection at different shear strength degrees.

<p> A method for tlie dynamic analysis· of planar coupled shear walls subjected to ground motions is developed herein. The method is capable of application to nonuniform coupled shear walls resting on flexible foundations. The possibility-of development of yield hinges at the ends of the connecting beams is included in the analysis . Also P-& Effect is incorporated in the stiffness of the structure. </p> <p> The method is based on the transfer matrix technique in combination with the continuum method. A step-by-step integration approach is used in solving the equation of motion. The response to a number of earthquake records are obtained. The effect of the rotational ductility factor of connecting beams is studied. </p> / Thesis / Master of Engineering (MEngr)

Performance-based design has gained interest in recent years among structural designers and researchers. Performance-based design includes selection of appropriate building sites, structural systems and configurations, as well as analytical procedures used in the design process, to confirm that the structure has adequate strength, stiffness and energy dissipation capacity to respond to the design loads without exceeding permissible damage states. Although performance-based seismic design has advanced for some materials and structural types, such as steel and reinforced concrete buildings and bridges, its application to light-frame structures remains largely unexplored. The objective of this research was to explore the potential for the application of performance-based engineering concepts to the design and assessment of woodframe structures subject to earthquakes. Nonlinear dynamic time-history analysis was used to predict the performance of shearwalls considering a suite of scaled characteristic ordinary ground motions to represent the seismic hazard. Sensitivity studies were performed to investigate the relative effects of damping, sheathing properties, fastener type and spacing, panel layout, and other properties on the performance of wood shearwalls. In addition, the effects of uncertainty in ground motions and variability in sheathing-to-framing connection hysteretic parameters were investigated. Issues such as the contribution of nonstructural finish materials, different seismic hazard regions, and construction quality also were investigated and modification factors to adjust peak displacement distributions were developed. The peak displacement distributions were then used to construct performance curves and design charts as a function of seismic weights for two baseline walls. Finally, fragility curves were developed for the baseline walls considering different nailing schedules, corresponding allowable seismic weights, and various overstrength (R) factors. / Graduation date: 2004

A nonlinear automated parameter fitted analytical model that numerically predicts the load-displacement response of wood frame shear walls subjected to static monotonic loading with and without vertical load is presented. This analytical model referred to as Analytical Model of wood frame SHEar walls subjected to Vertical load (AMSHEV) is based on the kinematic behavior of wood frame shear walls and captures significant characteristics observed from experimental testing through appropriate modeling of three failure mechanisms that can occur within a shear wall under static monotonic load: 1) failure of sheathing-to-framing connectors, 2) failure of vertical studs, and 3) uplift of end studs from bottom sill. Previous models have not accounted for these failure mechanisms as well as the inclusion of vertical load, which has shown to reveal beneficial effects such as increasing the ultimate load capacity and limiting uplift of the wall as noted in experimental tests. Results from the proposed numerical model capture these effects within 7% error of experimental test data even when different magnitudes of vertical load are applied to predict the ultimate load capacity of wood frame shear walls.

Non-ductile reinforced concrete frame buildings constitute an important part of the vulnerable buildings in seismic regions of the world. Collapse of non-ductile multi story concrete buildings during strong earthquakes in the past resulted in severe casualties and economic losses. Their rehabilitation through retrofitting is a critical issue in reducing seismic risks worldwide. A displacement-based retrofitting approach is presented in this study for seismic retrofitting of medium height non-ductile concrete frames. A minimum amount of shear walls are added for maintaining the deformation levels below the critical level dictated by the existing columns in the critical story, which is usually at the ground story. Detailing of shear walls are based on conforming to the reduced deformation demands of the retrofitted frame/wall system. Member-end rotations are employed as the response parameters for performance evaluation. Initial results obtained from the proposed displacement based approach have revealed that jacketing of columns and confining the end regions of added shear walls are usually unnecessary compared to the conventional force-based approach, where excessive force and deformation capacities are provided regardless of the actual deformation demands.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on Jan. 11, 2010. Major professor: Daniel C. Jansen. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Civil and Environmental Engineering." "December 2009." Includes bibliographical references (p. 176-180).