Showing papers on "Shear wall published in 2001"

Cyclic Analysis of Wood Shear Walls

Abstract: A simple numerical model to predict the load-displacement response and energy dissipation characteristics of wood shear walls under general quasi-static cyclic loading is presented. In this model the shear wall is comprised of three structural components: rigid framing members, linear elastic sheathing panels, and nonlinear sheathing-to-framing connectors. The hysteretic model for the sheathing-to-framing connector takes account of pinching behavior and strength and stiffness degradation under cyclic loading. A robust displacement control solution strategy is utilized to predict the wall response under general cyclic loading protocols. The shear wall model has been incorporated into the computer program CASHEW (Cyclic Analysis of SHEar Walls). The predictive capabilities of this program are compared with monotonic and cyclic tests of full-scale wood shear walls. It is shown that this model can accurately predict the load-displacement response and energy dissipation characteristic of wood shear walls under general cyclic loading. As an application of the CASHEW program, a procedure is presented for calibrating a single degree-of-freedom system to predict the complete nonlinear dynamic response of shear walls under seismic loading.

Seismic Behavior and Design of Steel Shear Walls

Abstract: Page 1 ACKNOWLEDGMENTS / Page 3 TABLE OF CONTENTS / Page 4 NOTATIONS AND GLOSSARY / Page 5

Analytical model for predicting shear strength of squat walls

Abstract: A softened strut-and-tie model for determining the shear strength of squat walls is proposed in this paper. The proposed model originates from the strut-and-tie concept and satisfies equilibrium, compatibility, and constitutive laws of cracked reinforced concrete. The shear capacities of 62 squat walls were calculated and compared with the available experimental results, and reasonable agreement was obtained. Based on the collected experimental data in this paper, the proposed physical model was used to study the effects of boundary elements, cyclic loading, and vertical loads on the wall shear strength. The softened strut-and-tie model can be further developed to improve the current shear wall design procedures by incorporating the actual shear resisting mechanisms in predicting shear strength of walls.

Modeling three-dimensional timber light-frame buildings

Abstract: A nonlinear finite-element model (LightFrame3D) is presented in this paper to study the perfor- mance of 3D timber light-frame buildings under static loading conditions. The uniqueness of the model is the implementation of a mechanics-based representation of the load-deformation characteristics of individual panel- to-frame nail connections in the diaphragm system. This approach requires as input basic material properties and static load-deformation characteristics of the connections. The model can analyze a light-frame building with varied material and structural components and combined loading conditions. Either load control or dis- placement control can be used as input history. The model was verified and tested by theoretical and experimental means and good agreements were achieved. The model can provide information on the hysteresis behavior of structures under cyclic loading and the torsional response of eccentric 3D buildings. Low-rise residential houses and small industrial and com- mercial buildings in North America are conventionally light- frame structures using wood-based materials. Typically, these are composed of 2D systems (i.e., shear walls, floors, ceilings, and roofs) and are highly indeterminate. These wood structural systems are generally believed to perform well under seismic loading when carefully constructed, which could be attributed to the high strength-to-weight ratio of timber as a building material, the redundancy of the whole system, and the ductility of connections. The structural integrity of wood frame buildings under the action of natural hazards is not necessarily guaranteed, as was shown in past earthquakes and hurricanes, especially in mul- tiple-story buildings with asymmetrical geometry. For many years, a large amount of experimental and analytical work has been done to understand the structural behavior of wood- based, light-frame systems. The work, to a great extent, has been limited to the study of 2D structural components, such as shear walls, roof and floor diaphragms, and metal connect- ors and fasteners, under static monotonic or cyclic loading. Experiments on full-scale light-frame houses have seldom been done due to the high costs and test demands. The knowl- edge obtained thus far about the structural behavior of com- plete wood buildings is mainly derived from construction prac- tice and a few experimental studies on major structural components. Analytical methods were also developed by a few research- ers to predict the structural performance of an entire building. Chehab (1982) developed a linear seismic analysis of a typical wood frame house. Even though the element mesh and input properties were coarse, the results captured the effects ob- served in earthquake-damaged houses, including torsional ef- fects resulting from a nonsymmetrical arrangement of the shear walls. Gupta and Kuo (1987) developed a simple linear elastic building model containing seven ''superelements'' and nine global degrees of freedom to analyze the building tested by Tuomi and McCutcheon (1974). The superelement was based on the shear wall model from their previous work

Seismic Resistance of Wood Shear Walls with Large OSB Panels

Abstract: Results are presented from studies on the seismic resistance of wood shear walls sheathed with large (2.4 x 2.4 m) and standard (1.2 x 2.4 m) size oriented strand board (OSB) panels. Comparisons were made among twelve 2.4 x 2.4 m walls tested under quasi–static monotonic and cyclic, as well as dynamic, loads. In push–over tests, all walls reached a drift of approximately 2.5% at maximum load. A 26% increase in shear capacity was achieved using large panels. The nails that would be at internal seams in walls with standard panels were redistributed around the exterior edges of some large panel walls. They also showed a 104% increase in shear capacity and a 30% increase in initial stiffness. These walls performed significantly better when tested dynamically, using the east–west motion recorded at Joshua Tree Station during the 1992 Landers, CA, earthquake. Their maximum drift was reduced by approximately 25% over standard walls. Damage incurred during dynamic tests consisted mainly of nail pullout and tear out. Renailing at these locations is simple and can restore the wall to a satisfactory performance level.

Simplified Seismic Design Approach for Friction-Damped Unbonded Post-Tensioned Precast Concrete Walls

Abstract: In this paper, the seismic design of unbonded posttensioned precast concrete walls with supplemental friction dampers is addressed. Significant research has been conducted on unbonded posttensioned precast walls because of their simplicity in construction and desirable seismic characteristics. The greatest disadvantage of these walls in seismic regions is an increase in the lateral displacements as a result of small inelastic energy dissipation. This paper shows that these displacements can be greatly reduced by using supplemental friction dampers along vertical joints between 2 walls. A simplified performance-based seismic design approach is introduced to reduce the maximum displacement of the walls below an allowable target displacement. Nonlinear dynamic time-history analyses of 6-, 8-, and 10-story prototype walls show that the design approach is effective in reducing the lateral displacements to prevent significant damage in the walls under maximum credible ground motions.

Matrix Analysis Of Structural Dynamics: Applications And Earthquake Engineering

Abstract: Characteristics of free and forced vibrations of elementary systems Eigensolution techniques and undamped response analysis of multiple-degree-of-freedom systems Eigensolution methods and response analysis for proportional and non-proportional damping dynamic stiffness and energy methods for distributed mass systems dynamic stiffness method for coupling vibration, elastic media and Pdeltal effect consistent mass method of frames and finite elements numerical integration methods and seismic response spectra for single- and multi-components seismic input formulation and response analysis of 3-D building systems with walls and bracings various hysteresis models of non-linear response analysis static and dynamic lateral-force procedures and related effects in building codes of UBC-94, UBC-97, and IBC-2000 problems solutions. Appendices: Lagrange's equation derivation of ground rotation vector analysis fundamentals transformation matrix between JCS and GCS transformation matrix between ECS and GCS for beam column transformation matrix and stiffness matrix of beams column with rigid zone computer program for Newmark method computer program for Wilson method computer program for CQC method Goel steel-bracing hysteresis model and computer program Takeda model for RC columns and beams and computer program Cheng-Mertz model for bending coupling with shear and low-rise shear walls and computer program Cheng-Lou axial hysteresis model for RC columns and walls and computer program.

Inelastic seismic response of concrete shear walls considering P-delta effects

Abstract: The inelastic response of a typical 12-storey ductile reinforced concrete flexural wall is examined under strong earthquake ground motions to determine the importance of P–delta effects and assess ...

Stucco fastening system

Abstract: A shear wall system comprises stucco fasteners consisting of an elongated first portion that is driven into a wood frame wall, and an elongated second portion that is completely embedded in a stucco wall panel. In one embodiment, the fasteners consist of an assembly having a first element that is driven into the wood frame wall, and a second annular element receiving a portion of the first element and that is embedded rigidly into the cement stucco wall. Ductile movement of the fastener components with respect to wood frame wall and the stucco wall provides energy dissipation.

Accidental Torsion in Buildings: Analysis versus Earthquake Motions

Abstract: A simplified analysis procedure has been developed to consider accidental torsion in building design that is rational and convenient relative to building codes. This procedure is extended and evaluated in this paper against measured accidental torsion determined from motions of 12 buildings—with nominally-symmetric plan—recorded during Northridge (1994), Loma Prieta (1989), Whittier (1987), and Upland (1990) earthquakes. The selected buildings include structures in reinforced concrete and in steel that cover a wide range of structural systems, including moment resisting frames, shear walls, braced frames, and hybrid systems. After the measured torsion is interpreted and compared to analytical estimates, it is demonstrated that this procedure is sufficiently accurate to be used in design applications.

Elastic analysis of asymmetric tall building structures

Abstract: A simplified elastic hand method for estimating forces in asymmetric multi-bent structures subjected to horizontal loading is presented. The structures may consist of combinations of coupled walls, rigid frames, braced frames and wall-frames with shear walls. Results for structures that are uniform in height compare closely with results from stiffness matrix analysis. The method is developed from coupled-wall deflection theory, which is expressed in nondimensional structural parameters. It accounts for bending deformations in all individual members as well as for axial deformations in the vertical members and is, therefore, more accurate for very tall structures. A closed solution of coupled differential equations for deflection and rotation gives the deflected shape along the height of the building. The proposed method of analysis offers a relatively simple and rapid means of comparing the shear forces and bending moments of different stability systems for a proposed tall building. The derivation of equations for analysis shown in this paper are for unisymmetric stability systems only, but the method is also applicable to general asymmetric structures. Copyright © 2001 John Wiley & Sons, Ltd.

Shear and normal stresses interaction in coupled structural systems

Abstract: A unified approach to evaluate the behavior of composite structural elements is proposed consid- ering the interaction between the shear and normal stresses due to the connecting system. The model assumes linear behavior for the materials and connection and allows one to analyze different structural problems in the serviceability conditions. Numerical examples show that many classical coupled problems could be analyzed by a unified approach; in particular, the coupled shear walls subject to horizontal loads, steel-concrete composite beams with stud connectors, and reinforced beams strengthened with external plates are considered.

Wood composite panels for disaster-resistant construction

Abstract: A wood sheathing panel, suitable for use in building construction, includes reinforcement strips of fiber reinforced polymer material incorporated into the panel. The reinforcement strips cover an area that is within the range of from about 5 to about 50 percent of the surface area of the panel. The reinforcement strips of fiber reinforced plastic material can be incorporated in the perimeter of the panel, or can be incorporated into the corners of the panel. The spacing of the intermittently incorporated reinforcement strips can generally coincide with a standard spacing of framing members so that when the wood sheathing panel is applied to a building frame, the reinforcement strips are generally aligned with framing members of the building. Preferably, the reinforcement strips are sufficient to provide an increased ductility over an equivalent unreinforced wood sheathing panel in an amount within the range of from about 75 percent to about 500 percent. A plurality of the wood sheathing panels of the invention can be assembled together in building construction (10) as one element of a group consisting essentially of shear walls (12, 14, 24, 26), horizontal diaphragms (20, 22) and roof diaphragms (28).

Seismic Response of Low-Rise Masonry Buildings With Flexible Roof Diaphragms

Abstract: : This study compares the responses from shaking-table testing and analytical predictions evaluated in the context of geometric scaling, to provide a coherent description of the seismic response of low-rise masonry buildings with flexible roof diaphragms. Two half-scale, low-rise reinforced masonry buildings with flexible roof diaphragms are subjected to carefully selected earthquake ground motion on the Tri-axial Earthquake and Shock Simulator at the Construction Engineering Research Laboratory. Damage to the half-scale specimens is assessed using published protocols. Geometric scaling analysis relates response and damage of the half-scale specimens to those of the full-scale prototype structures. Linear elastic modeling is simplified to a generalized two-degrees-of-freedom idealization. Response-spectrum analysis of such an idealization is accurate and justified for prediction of dynamic response of the half-scale specimens and the corresponding full-scale prototype. It is shown that low-rise masonry buildings with flexible roof diaphragms can be designed for seismic loads as single-degree-of- freedom systems, using the degree of freedom associated with the in-plane response of the diaphragm in the building's transverse direction, rather than the degree of freedom associated with the in-plane responses of the shear walls.

Effects of loading rate on mechanical behavior of SRC shearwalls

Abstract: In order to investigate the effect of the loading rate on the mechanical behavior of SRC shearwalls, we conducted the lateral loading tests on the 1/3 scale model shearwalls whose edge columns were reinforced by H-shaped steel The specimens were subjected to the reversed cyclic lateral load under a variable axial load The two types of loading rate, 001 cm/sec for the static loading and 1 cm/sec for the dynamic loading were adopted The failure mode in all specimens was the sliding shear of the in-filled wall panel The edge columns did not fail in shear The initial lateral stiffness and lateral load carrying capacity of the shearwalls subjected to the dynamic loading were about 10% larger than those subjected to the static loading The effects of the arrangement of the H-shaped steel on the lateral load carrying capacity and the lateral load-displacement hysteresis response were not significant

Design for Drift and Lateral Stability

Abstract: This chapter deals with the problems of drift and lateral stability of building structures. Design for drift and lateral stability is an issue that should be addressed in the early stages of design development. In many cases, especially in tall buildings or in cases where torsion is a major contributor to structural response, the drift criteria can become a governing factor in selection of the proper structural system. The lateral displacement or drift of a structural system under wind or earthquake forces, is important from three different perspectives: 1) structural stability; 2) architectural integrity and potential damage to various non-structural components; and 3) human comfort during, and after, the building experiences these motions. In design of building structures, different engineers attribute various meanings to the term “stability”. Here, we consider only those problems related to the effects of deformation on equilibrium of the structure, as stability problems. Furthermore, we will limit the discussion to the stability of the structure as a whole. Local stability problems, such as stability of individual columns or walls, are discussed in Chapters 9,10, and 11 of the handbook. Several practical methods for inclusion of stability effects in structural analysis as well as simplified drift design procedures are presented. These approximate methods can be valuable in evaluation of the potential drift in the early stages of design. Numerical examples are provided to aid in understanding the concepts, and to provide the reader with the “hands-on” experience needed for successful utilization of the material in everyday design practice.

Adaptive FE Analysis of RC Shells. II: Applications

Abstract: This paper deals with the application of an adaptive calculation scheme to ultimate load analyses of reinforced concrete (RC) plates and shells. The influence of the user-prescribed accuracy on the numerical results, especially on the ultimate load, is investigated. Three examples are considered: (1) a shear wall panel; (2) a circular plate; and (3) an RC cooling tower subjected to dead load and wind load. In addition to adaptive finite element (FE) analyses, single-mesh calculations on the basis of uniformly refined meshes are performed.

Full-reverse construction technology for basement

Abstract: A full-reverse construction technology for basement includes such steps as constructing the underground continuous wall surrounding the basement (which is the combination of retention wall, retainingwall and bearing wall), installing different kinds of reinforced concrete columns, and excavating from top to bottom layer by layer while building up upper structure including shear walls and key cylinders. Its advantages include saving time and raw materials, and high integral rigid of high building.