Showing papers on "Shear wall published in 1993"

Masonry Structures: Behavior and Design

Abstract: The world of ancient masonry the world of modern masonry building design masonry materials behaviour of masonry assemblages reinforced beams and lintels flexural walls loadbearing walls under axial load and out-of-plane bending columns and pilasters shear walls infill walls and partitions masonry veneer and cavity walls connectors application of building science for environmental loads construction considerations and details design of loadbearing single storey masonry buildings.

Experimental Study of Thin Steel‐Plate Shear Walls under Cyclic Load

Abstract: The results of an investigation into the seismic behavior of unstiffened thin steel–plate shear walls is presented. Little work has been done in the past to investigate the behavior of unstiffened thin steel–plate shear walls in resisting lateral forces due to earthquakes or wind. Described is the cyclic testing of six, 1:4 scale specimens that include a moment-resisting frame, three specimens with varying plate thickness and moment-resisting beam-to-column connections, and two specimens with shear beam-to-column connections. Dissimilarities in behavior modes are found when the specimens of different plate thickness are compared to each other. The specimens with thinner plates exhibit an inelastic behavior that is controlled primarily by yielding of the thin plate, and the nonlinear system behavior is predominantly due to the stretching of the plate and the formation of a diagonal tension field. The specimens with thicker plates show an inelastic behavior that is primarily governed by the columns, and the capacity of the specimen with the thickest plate is limited by the instability of the column.

Postbuckling Behavior of Steel-Plate Shear Walls under Cyclic Loads

Abstract: In current design practice the capacity of a steel‐plate shear wall is limited to the elastic buckling strength of its plate panels. This practice results not only in a conservative design, but also in an undesirable one where the columns yield and may buckle before the plate reaches a fraction of its capacity. Plate buckling is not synonymous with failure and if the plate is adequately supported along its boundaries, as in the case of the shear wall, the postbuckling strength can be several times the theoretical buckling strength. Furthermore, due to the unavoidable out‐of‐plane imperfections, no change in the plate behavior will be observed at the theoretically calculated buckling load. Although the post‐buckling behavior of plates under monotonic loads has been under investigation for more than half a century, this behavior under cyclic loading has not been investigated until recently. One test was conducted at the University of Alberta and 10 tests were conducted at the University of Maine. In this pa...

Behavior‐Based Method to Determine Design Shear in Earthquake‐Resistant Walls

Abstract: For earthquake-resistant design of reinforced concrete structures, the shear force for frame elements is established on the basis of the proportions and flexural strength of the element according to the American Concrete Institute standard 318-89 (1989), the Applied Technology Council Standard 3-06 (1989), and the Uniform Building Code, published in 1988. In this paper, a similar procedure is proposed for walls in medium-rise, reinforced concrete buildings. Results of small-scale dynamic tests of nine- and ten-story structures with walls are presented to provide data with which to evaluate methods of estimating base shear. Maximum base-shear response during these tests consistently exceeded limit analysis estimates calculated assuming a linearly varying acceleration distribution. If the observed force distribution is used in estimating base shear, the limit analysis estimates are acceptable. The need to take into account variations of inertial force distribution with base-motion intensity is supported by experimentally observed behavior, by modal analysis, and by nonlinear response-history analysis. After discussing other factors that influence maximum base shear, such as strain rate, strain hardening, and systematic experimental error, a design procedure for estimating shear demand for walls that reflects observed behavior is proposed.

Vibration of Buildings to Wind and Earthquake Loads

Abstract: 1 Fundamentals of Structural Dynamics- 11 Introduction- 12 One-degree-of-freedom System- 121 Equation of Motion- 122 Free Vibration- 123 Response to Harmonic Loading- 124 Response to Arbitrary Loading- 13 Multi-degree-of-freedom System- 131 Equation of Motion- 132 Undamped Free Vibration- 133 Forced Vibration Response- 14 Continuous System- 141 Equation of Motion- 142 Free Vibration- 143 Orthogonality of Modes of Vibration- 144 Forced Vibration Response- 2 Behaviour of Buildings Under Lateral Loads- 21 Structural Systems- 211 Braced Frame Structures- 212 Rigid Frame Structures- 213 Shear Wall Structures- 214 Shear Wall-Frame Structures- 215 Framed Tube Structures- 216 Tube in Tube Structures- 217 Bundled Tube Structures- 218 Outrigger-braced Structures- 22 Modelling of Structural Systems- 221 Behaviour of Buildings- 222 Modelling of Plane Structures- 223 Modelling of Three-dimensional Structures- 224 Reduction of Size of Model- 3 Dynamic Effects of Winds on Buildings- 31 Characteristics of Wind- 311 Mean Wind Speed- 312 Turbulence- 313 Integral Scales of Turbulence- 314 Spectrum of Turbulence- 315 Cross Spectrum of Turbulence- 32 Wind-induced Dynamic Forces- 321 Forces due to Uniform Flow- 322 Forces due to Turbulent Flow- 33 Along-wind Response- 331 Point Structures- 332 Line-like Structures- 333 Evaluation of Peak Response- 34 Across-wind Response- 35 Torsional Response- 36 Serviceability Requirements- 4 Wind Tunnel Studies of Buildings- 41 Introduction- 42 Rigid Model Studies- 43 Aeroelastic Model Studies- 431 Aeroelastic Model with Linear Mode (Semi-rigid Model)- 432 Aeroelastic Model with Shear-Flexure Mode- 433 Aeroelastic Model with Coupled Modes- 44 High-frequency Force Balance Model- 45 Pedestrian Wind Studies- 5 Analysis of the Behaviour of Buildings During Earthquakes- 51 Earthquake Loading- 52 Response Spectrum Analysis of SDOF- 53 Response Spectrum Analysis of MDOF- 54 Site and Soil-Structure Interaction Effects- 55 Equivalent Lateral Load Analysis- 56 Inelastic Response Analysis- 6 Earthquake-resistant Design of Buildings- 61 Desigft Philosophy- 62 Structural Configuration- 621 Vertical Configuration- 622 Horizontal Configuration- 63 Steel Structures- 631 Moment-Resisting Frame (MRF)- 632 Concentrically Braced Frame (CBF)- 633 Eccentrically Braced Frame (EBF)- 634 Knee-Brace-Frame (KBF)- 635 Applications- 64 Concrete Structures- 641 Moment-resisting Frames- 642 Shear Wall Structures- 643 Coupled Shear Walls

Lateral Load Sharing by Diaphragms in Wood‐Framed Buildings

Abstract: Current analysis and design procedures for light‐frame wood buildings do not give consideration to the complex three‐dimensional structural response of the buildings. A full‐scale single‐story wood house is constructed and tested under lateral loads at various stages of loading to evaluate the structural response and load‐sharing characteristics. Different sheathings, fastener arrangements, and openings are incorporated to create shear walls with varying stiffnesses. Extensive force and displacement readings are made of the building during testing to quantify the structural response. Results of the study indicate that the roof diaphragm affected the distribution of lateral load to the shear walls of the building. The roof diaphragm behaved nearly like a rigid diaphragm. Load distribution among the shear walls is a function of wall stiffness and position within the building. The walls transverse to the loading direction carried between 8% and 25% of the applied lateral load. Stiffness contributions provide...

Mixed Finite Element Method for Analysis of Coupled Shear/Core Walls

Abstract: Theoretically, the finite element method can be applied to any type of building structure. However, not all elements are suitable for coupled wall analysis. Basically, the plane stress elements that model the walls should: (1) Have in‐plane rotations defined as vertical fiber rotations in order to allow direct connection and ensure compatibility with the beam elements; (2) be able to represent the strain state of pure bending so as to avoid parasitic shears; and (3) span at most only one story so that stress discontinuities at floor levels can be allowed. In this paper, two existing elements, namely Cheung's beam‐type element and Kwan's strain‐based element, which satisfy these criteria, are combined together to model shear/core wall structures so as to make the best use of these two elements. Two transition elements that behave like Cheung's element at one vertical edge and like Kwan's element at the other vertical edge are developed. The two existing elements and the two newly developed elements togethe...

Behavior of curtailed wall-frame structures

Abstract: The lateral load resistance of tall wall-frame building structures comprising a combination of moment-resisting frames and shear walls that are reduced in size or terminated entirely at intermediate heights is investigated. A generalized theory for the deflection of such structures is developed on the basis of a continuum model, to show that curtailment of the walls is not necessarily detrimental to the performance of the structure. Indeed, if the walls are curtailed within a certain height region the forces in the upper part of the frame are reduced while the top deflection is negligibly affected. An expression for the deflection of curtailed uniform wall-frame structures is minimized to provide guidance for the optimum level of wall curtailment to cause a minimum increase in the top deflection. Guidance on the level of curtailment without detriment to the structure’s performance for practical nonuniform wall-frame structures is given.

Improved wide-column-frame analogy for shear/core wall analysis

Abstract: The wide-column-frame analogy is popular in design offices for the analysis of shear/core wall buildings. However, it has been found to yield erroneous results in cases where shear deformation of the walls is significant, e.g. core walls subjected to torsion. There are two sources of error. First, due to discrete modeling of the vertical joints between adjacent planar wall units, the wall elements are subjected to parasitic moments, which cause artificial flexure of the elements and eventually excessive shear deformation of the walls. Second, the rotations of the coupling beams at the beam-wall joints have been mistaken as equal to the rotations of the horizontal rigid arms and, as a result, the beam end rotations are underestimated by amount equal to the shear strain in the walls. It is proposed that these problems be resolved by: (1) Adjusting the shear deformation factor of the wall elements to compensate for the errors in shear deformation due to artificial flexure; and (2) using beam elements with vertical rigid arms for the coupling beams, so as to eliminate the errors in beam end rotations. Substantial improvement in accuracy is achieved with these modifications.

System of programs for analysis of three‐dimensional shear wall structures

Abstract: The paper presents a system of programs for calculating stresses and displacements in three-dimensional shear wall structures with uniform properties throughout the height. The analysis is carried out on the basis of the continuous connection method. The system allows for considering lateral and vertical loads, arbitrarily located in the plan and arbitrarily distributed along the height. The system is user-oriented and inexpensive in operation. Two numerical examples are given in the paper.

Computed versus Observed Inelastic Seismic Low‐Rise RC Shear Walls

Abstract: A technique of calculating inelastic deformation of low-rise shear walls having height-width ratios of 0.5 and 0.75 without boundary elements is presented with consideration of the coupling effect for bending and shear deformations as well as the deformation due to base rotation. An interaction surface of moment, shear, and curvature or moment, shear, and shear strain is developed. The deflections at crack, yield, and ultimate loadings can be calculated separately from bending and shear deformations, which are compared favorably with experimental results. The shear deformation is significant for the low-rise walls studied because the deformation due to bending deformation is about 40–60% of the total deformation after the walls have reached 20% of ultimate deformation. The hysteresis rules are developed for both bending and shear deformations on the basis of theoretical and experimental studies. Favorable comparisons between the calculated and experimental responses were observed for individual walls and a low-rise two-story building on a shaking-table test. A computer program was developed for structural system analysis subjected to seismic excitations.

Steel Panel Encased R.C. Composite Shear Walls

Abstract: In order to make clear the fundamental resisting mechanisms of composite shear walls, tests are carried out on the composite unit rigid frames with various infilled shear walls. Composite shear walls are classified into the following three fundamental types; (a) reinforced concrete shear panel infilled in composite frame, which are already in common use, (b) steel band bracing embedded in reinforced concrete shear panel, which belongs to the so-called open web panel type, (c) steel panel with or without covering reinforced concrete shear panel, which belongs to the so-called full web panel type. Test results show that the resisting mechanism of reinforced concrete shear panel infilled in composite rigid frame is composed of diagonal compression field of the infilled concrete, therefore the initial stiffness, ultimate resistance become very high. But because of the compression fracture of concrete, deformability is very small (such as 0.005 in story sway angle). Through the formation of diagonal compression field of concrete, the surrounding frames are expanded to outsides. On the contrary, the resisting mechanism of steel panel infilled in rigid frame is composed of diagonal tension field of the buckled steel panel; therefore, the initial stiffness is not so high but through the formation of diagonal tension field the ultimate strength is fairly high. The plastic deformation is generally very large because of tensile yielding of steel. The surrounding frame are contracted into inside through the diagonal tension of the buckled shear panel. The optimum combination of these two fundamentally opposite resisting mechanisms of infilled reinforced concrete or steel shear panel, makes it possible to control the aseismic characteristics of a composite structure.

Experimental assessment of low‐aspect‐ratio, reinforced concrete shear wall stiffness

Abstract: Low-aspect-ratio, reinforced concrete shear walls are the primary lateral-load-carrying element in many structures designed for protective purposes. A review of the technical literature shows that considerable uncertainty exists regarding the elastic stiffness these structures will exhibit during seismic excitation. Because of this uncertainty, current design practice often employs a stiffness reduction factor. In an attempt to develop accurate information regarding the stiffness of these structures, 13 shear wall elements were tested statically; dynamically, with simulated seismic base excitations on a shake table; and with experimental modal analysis procedures. Results of these tests show that the shear wall's stiffness can be accurately estimated with a mechanics-of-materials analysis that accounts for shear deformation

Nonlinear 3-D behavior of shear-wall dominant RC building structures

Abstract: The behavior of shear-wall dominant, low-rise, multistory reinforced concrete building structures is investigated. Because there are no beams or columns and the slab and wall thicknesses are approximately equal, available codes give little information relative to design for gravity and lateral loads. Items which effect the analysis of shear-wall dominant building structures, i.e., material nonlinearity including rotating crack capability, 3-D behavior, slab-wall interaction, floor flexibilities, stress concentrations around openings, the location and the amount of main discrete reinforcement are investigated. For this purpose 2 and 5 story building structures are modelled. To see the importance of 3-D modelling, the same structures are modelled by both 2-D and 3-D models. Loads are applied first the vertical then lateral loads which are static equivalent earthquake loads. The 3-D models of the structures are loaded in both in the longitudinal and transverse directions. A nonlinear isoparametric plate element with arbitrarily places edge nodes is adapted in order to consider the amount and location of the main reinforcement. Finally the importance of 3-D effects including the T-C coupling between walls are indicated.

Lateral Load Distribution in Asymmetrical Tall Building Structures

Abstract: An approximate method is presented for the analysis of the distribution of lateral forces among the components of a three-dimensional tall building structure that consists of assemblies of shear walls, coupled walls, and rigidly jointed frames, subjected to both bending and torsion. The load distribution on each element is assumed to be represented sufficiently accurately by a polynomial in the height coordinate, together with a concentrated interactive force at the top. The presence of the latter is essential for obtaining accurate results as simply as possible. A set of flexibility influence coefficients, relating the deflection at any level to any particular load component, is established for each element using continuum techniques. Use of the equilibrium and compatibility equations at any desired set of reference levels enables the load distribution on each element to be determined. Good results appear to be achieved for regular structures by using no more than about four reference levels, requiring the use of matrices of no more than order 4 in the analysis.

Case study of the performance of prestressed concrete buildings during the 1985 mexico earthquake

Abstract: The overall effects of the 1985 Mexico earthquake on buildings are summarized, with special consideration of the performance of prestressed concrete buildings. Then, for five typical prestressed concrete buildings, results of analyses of the dynamic response, with due consideration of the soil-structure interaction, are presented. In general, the computed response of the buildings under the effect of a ground motion simulating the 1985 earthquake, corresponded reasonably well with their observed performance. Nevertheless, in some cases the analyses indicated that the buildings should have experinced a greater nonlinear behavior than the ones perceived from their level of damage. Some reasons for these differences are discussed. Recommendations on earthquake-resistant design of prestressed concrete buildings are given. The importance of providing lateral stiffness by shear walls or bracing, and of achieving ductility and continuity through mild steel reinforcement, is emphasized.

Ductility of low-rise structural walls

Abstract: Based on equilibrium and compatibility conditions, as well as a stress–strain relationship for softened concrete, a truss model theory is derived to predict the strengthand behaviour of low-rise reinforced concrete shear walk m e theoretical prediction was compared to the tests of twenty- four shear walls and was found to be applicable throughout the loading history. The effects of material properties (including steel yielding stress and concrete compressive strength) and reinforcement ratio on the ductility of low-risestructural walls was firther studied using numerical experimentation. It was found from this study that the ductility factor of four can be reached when the steel yielding stress, the concrete compressive strength and the reinforcement ratio are 280 N/mm2, 56 N/mm2 and 0·0025, respectively.

Failure Modes of Low‐Rise Shear Walls

Abstract: A summary of available data concerning the structural response of low-rise shear walls is presented. These data will be used to address two failure modes associated with shear wall structures. First, the data concerning the seismic capacity of the shear walls are examined, with emphasis on excessive deformations that can cause equipment failure. Second, the data concerning the dynamic properties of shear walls (stiffness and damping) that are necessary for computing the seismic inputs to attached equipment are summarized. This case addresses the failure of equipment when the structure remains functional.

Performance of prefabricated high strength welded wire grids in ductile concrete shear wall boundary elements

Abstract: SUMMARY The performance of a new proprietary concrete reinforcement product, BauMesh, when used as confinement reinforcement in ductile concrete shear walls is discussed. Large material and labor savings are achieved when concrete shear walls are reinforced with these new high strength welded wire ladders positioned at close spacing (3" o.c.) along the length of the longitudinal reinforcement to ensure a non-brittle ductile response to violent earthquake generated cyclic forces. Design, quality control during manufacture, installation, and the observed performance of a 17-story San Francisco ductile shear wall building during the Loma Prieta earthquake are discussed.

Stiffness and Damping Properties of a Low Aspect Ratio Shear Wall Building Based on Recorded Earthquake Responses

Abstract: An investigation into the structural properties and seismic responses of a low aspect ratio shear wall building, which has construction similarity to typical nuclear plant structures, has been performed using actual recorded earthquake motions This effort used a combination of modal identification to obtain structure modal parameters directly from the recorded motions, and elastic structural analysis using methods and criteria frequently employed by the nuclear industry Modal parameters determined by modal identification provide excellent fits to the building motions recorded during the 1984 Morgan Hill earthquake Modal parameters identified for the 1989 Lorna Prieta earthquake are more uncertain Investigation of building stiffnesses generally confirms the adequacy of bounding estimates currently recommended for nuclear plant structure seismic analysis Damping values identified for this building supplement the database being compiled to investigate current nuclear plant structure damping criteria