Showing papers on "Shear wall published in 1984"

Evaluation of shear and flexural deformations of flexural type shear walls

Abstract: In order to predict the inelastic response of reinforced concrete structures under dynamic earthquake loading, hysteretic behaviour of their structural components must be evaluated appropriately. Though various restoring force models have already been proposed for beams and columns, hysteretic behaviour of flexural type shear walls remains unclear in many respects. In this paper, an evaluation method of distributing the total deformation of a shear wall into the flexural and shear deformation is mentioned and an analytical one of evaluating these deformations is proposed. The comparison of analytical results with test results of shear walls is carried out.

Generalized Method for Estimating Drift in High‐Rise Structures

Abstract: An approximate method for estimating the drift of multi-bent structures is presented. Structures that are singly or doubly symmetrical in plan and comprising any combination of shear walls, coupled walls, rigid frames and braced frames, can be considered. Results for structures that are uniform with height compare closely with results from stiffness matrix computer analyses. The method is developed from coupled-wall deflection theory which is expressed in terms of two non-dimensional structural parameters. The parameters involve three structural properties: the individual bending stiffness of the walls, the overall bending stiffness related to axial deformations of the walls and racking stiffness caused by reverse bending of the beams. Similar properties are calculated for rigid frames, braced frames and shear walls and then combined to determine values of the two parameters for the total structure. These values are then substituted into a generalized equation to obtain the deflection profile. This method accounts for axial deflection of the vertical components and is, therefore, more accurate for very tall structures. The method provides a rapid estimate of the drift in a high-rise structure as well as allowing an easy means of comparing the suitability of different structural solutions for a tall building. The method also illustrates the fundamental dependence of the behavior of continuous type cantilevers on two characteristic parameters.

Simple Analogous Frames for Shear Wall Analysis

Abstract: Two types of analogous frames have been developed for the stress analysis of shear walls. They provide an alternative to the finite element technique for shear walls that can be subdivided into a mesh of rectangular modules. One analogous frame is similar to the widely used wide‐column analogous frame, except for the addition of diagonal braces in each module. The diagonal braces prevent the interference of the bending and shear stiffnesses, which occur in the ordinary wide‐column analogy, and therefore allow the more accurate representation of shear walls with a high shear to moment ratio. The second analogous frame also includes horizontally rigid arms and braces, but the central column of the previous frame is omitted and replaced by a column on one vertical edge and a hinged link on the other. A standard frame analysis program is used to analyze the analogous frames. The results compare in accuracy with simple rectangular plane stress finite elements.

Free vibration of asymmetric shear wall-frame buildings

Abstract: The Galerkin method of weighted residuals is used to determine the frequencies and associated mode shapes of asymmetric shear wall-frame structures. The governing equations are formulated using the continuum approach by idealizing the structure as a shear-flexure beam. Varying properties along the height of the building are considered. The effect of translational, rocking and torsional flexibilities of the foundation on the natural frequencies is also investigated. The method presented herein utilizes polynomial and transcendental displacement functions, and is found to be simple, versatile and efficient.

Outrigger‐Braced Coupled Shear Walls

Abstract: An investigation is made of the feasibility of using a top outrigger to stiffen a pair of coupled shear walls. Based on the continuous connecting medium, a closed solution to the problem is reached. The solution presented also includes the analysis of coupled shear walls stiffened by a top beam. A numerical example is given to indicate the efficiency of the top stiffening outrigger in reducing the lateral deflections in the pair of coupled shear walls.

Racking Performance of Light-Frame Walls Sheathed on Two Sides.

Abstract: : Walls in light-frame construction resist in-plane shear forces, known as racking forces, by the interaction of the sheathing diaphragm and wood frame through the fasteners. Wall performance tests provide racking strength for a particular sheathing, fastener and wood frame configuration. Small-scale shear wall length (aspect ratio) on racking resistance, (2) additive nature of single-sided walls to determine racking resistance of double-sided walls, and (3) relative racking resistance of interior- and exterior-type wall construction. Results to an aspect ratio of 3 indicate strength and stiffness values relate linearly to wall length. Double-sided wall behavior can be predicted by summing single-sided wall values. On the basis of small-scale static tests, interior wall construction (gypsum sheathing) does provide significant racking resistance relative to racking resistance of exterior wall construction (plywood sheathing). This information will be helpful to building designers and code officials to determine racking resistance of shear walls.

Charts for Seismic Design of Frame-Wall Systems

Abstract: Charts are presented for the seismic design by the response spectrum method of fixed-based multistory buildings consisting of solid shear walls and frames, symmetrically arranged in plan and having constant properties along the height. The building is treated as a continuum with the frames modelled as a single shear beam, and the first three normal modes of the building are utilized for evaluating various modal responses, namely, the bending moments and the shear forces in the wall, the shear force in the frame and also the top deflection, the contribution of only the fundamental mode being considered for the last named response. The charts present the distributions of the modal moments and shears along the height of the building, which should allow the quantity of reinforcements to be varied for achieving economy. The results are presented for practical values of the nondimensional parameter which incorporates all the geometric and material properties governing the behaviour of the system. The use of the design charts is illustrated by an example of a 15 storied building.

Thin-Walled Core Element for Multistory Buildings

Abstract: The stiffness matrix of a thin‐walled open‐section element including the effect of shear strains due to warping is presented Closed form expressions for the stiffness coefficients are obtained for the case of negligible uniform torsion stiffness; an iterative procedure, based on a compatibilization scheme, is presented for the case when both uniform torsion and warping shear deformations are considered The proposed element can be used for modeling core shear walls in multistory buildings and is suitable for implementation in a computer program based on the direct stiffness method Two simple examples of multistory core wall structures are presented to assess the effect of uniform torsion stiffness and warping shear deformation on dynamic torsional behavior

Stresses in Slabs Coupling Flanged Shear Walls

Abstract: A finite element analysis has been made of the stress distribution in a slab coupling a pair of laterally loaded flanged shear walls. For a unit relative wall rotation, or relative vertical displacement, distributions of critical bending moments have been determined, and a generalized design curve presented to allow rapid evaluations of the maximum moments in a slab coupling a pair of T‐shaped walls. An investigation of the distributions of interactive shear forces between wall and slab, in conjunction with the usual design assumptions regarding shear failure of similar flat plate structures, has enabled a design technique to be proposed for checking against punching shear failure of the slab. Design curves are also presented for the critical bending moments in slabs coupling plane and T‐shaped walls, and L‐shaped walls.

Seismic fragility of reinforced concrete structures and components for application to nuclear facilities

Abstract: The failure and fragility analyses of reinforced concrete structures and elements in nuclear reactor facilities within the Seismic Safety Margins Research Program (SSMRP) at the Lawrence Livermore National Laboratory are evaluated. Uncertainties in material modeling, behavior of low shear walls, and seismic risk assessment for nonlinear response receive special attention. Problems with ductility-based spectral deamplification and prediction of the stiffness of reinforced concrete walls at low stress levels are examined. It is recommended to use relatively low damping values in connection with ductility-based response reductions. The study of static nonlinear force-deflection curves is advocated for better nonlinear dynamic response predictions. Several details of the seismic risk analysis of the Zion plant are also evaluated. 73 references.

Frames with Staggered Panels: Experimental Study

Abstract: A structural system consisting of story-deep and bay-wide discrete panels to resist lateral loads is investigated. To study the overall behavior of this system and to compare with the conventional shear wall frame, four perspex models were tested for static as well as dynamic response. To investigate the behavior of a discrete shear panel and to study the effect of stress-concentration at panel-corners where skeletal members meet, three reinforced concrete panels were tested. The proposed system is found to provide adequate lateral stiffness to resist horizontal loads such as wind and earthquake forces. Discrete panels cannot be idealized as line elements (wide columns with rigid arms), and the finite element method must be used for the analysis of staggered panel frames. Local failure at corners of a panel can be avoided by extending the girder and column reinforcements through the length and height of the panel. Reinforcement in the interior of a panel can be the minimum required to resist the stresses due to shrinkage, temperature, and creep.

Composite Action Between Slabs and Lintel Beams

Abstract: Based on a finite element analysis, a study is made of the composite action of a floor slab and lintel beam coupling a pair of laterally loaded plane shear walls. The relative influences of a range of structural parameters on the composite stiffness and effective slab width are evaluated, and design curves are presented to facilitate their determination in practical situations. It is shown that the influence of the coupling action is significant only when the lintel beam is relatively flexible.

Mechanical Nonlinear Shear Wall Model

Abstract: The nonlinear performance of a shear wall building can often only be described by full-scale testing or nonlinear analysis. Full-scale tests are time consuming and expensive; nonlinear analysis often is mathematically complex so that limiting assumptions are necessary to simplify the problem. This study describes a mechanical model which can simulate the nonlinear static or dynamic response of a shear wall or diaphragm. An assembly of these models can then simulate entire buildings and is suitable for the experimental investigation of the linear and nonlinear, static or dynamic response of shear wall structures.

Dynamic Interaction of Inclusion-Soil-Foundation System

Abstract: The effects of an inclusion on the dynamic response of a shear wall foundation system subjected to plane harmonic SH‐waves are investigated. The inclusion and foundation are modeled as having circular and semicircular cross sections, respectively. A closed form solution for the inclusion‐soil‐foundation interaction problem is obtained by the method of wave functions expansion. The image technique is employed to account for the reflection of waves at the ground surface. The numerical studies carried out indicate that the response of the foundation and the shear wall are influenced by both the size and location of the inclusion, especially in the low frequency range. On the contrary, for any inclusion location, the direction of excitation has greater influence on the response of the system at higher frequencies. It is also observed that the effect of the inclusion on the system response decreases with an increase in the mass of the shear wall.

Statistical analysis of the inelastic response of shear structures subjected to earthquakes

Abstract: Inelastic deformations of structures subjected to strong earthquakes are commonly accepted by Aseismic Codes; some discrepancies exist in the different procedures proposed to design a structure for which the ductility demand is to be limited within acceptable values. To have a better insight into the seismic behaviour of multi-degree-of-freedom structures beyond the elastic range, the dynamic elasto-plastic response of a ten-storey shear system under two sets of artificial and recorded accelerograms is studied considering different stiffness-strength distributions and constitutive laws. Statistics of the results are presented, demonstrating the dependence of the overall and storey ductility values and of their ratio on the characteristics of the structure and excitation.

Optimum design of reinforced concrete shear walls

Abstract: The recently published New Zealand Code of Practice for the Design of Concrete Structures (NZS 3101:1982) and the newly amended Code of Practice for General Structural Design and Design Loadings for Buildings (NZS 4203) permit a variety of possible design approaches for reinforced concrete shear wall structures. A series of wall designs for dimensionally similar four-storey and eightstorey buildings has been carried out and a comparison of con­ struction cost estimates obtained together with an assessment of the relative design effort required for the different design options.

Effect of wall base rotation on behaviour of reinforced concrete frame-wall building

Abstract: This paper reports the tests of multistorey frames including a base rotating wall under lateral load reversals. The wall base rotation limited the input forces and prevented damage in the wall. The beams, however, were forced to deform much during the wall rotation. The inelastic behaviour of frame members and the uplifting rotation of a structural wall at its base were idealised, and the effect of wall base rotation on frame behaviour was studied through inelastic earthquake response analysis. The base rotating shear walls performed better than or as good as flexural yielding walls.

Method of estimation of rotational rigidity of the intermediate connections of framed shear walls for their equivalent diagonally-braced frames

Abstract: memorized in the cornputer are made. LttA method of estimating flexural rigidity of beams in the equivalent frame, corresponding to the edge beams of the one-bay-one-story framed shear walls, was reFig'1 :qhueivMa?ednetl sO/fru:q ieVtahloednt fraMe in conyentional ported in the previous papeF). A method of estimating flexural rigidity of beams in the equivalent frame, corresponding to the edge beams of the multi-bay framed shear walls, is assumed to be the same as the method in a previous study (see reference 2) by dividing the multi-bay framed shear walis into one-bay-one-story framed shear walls. In this paper, one-bay-two-story and two-bay-one-story framed shear walls, whose exact solutions were obtained by using Airy's stress functions, are adopted as examples of continuous framed shear walls, 1. Analyzed Frames The configuration of the one-bay-two-story and two-bay-one-story framed shear walls (hereafter referred to as

Load-limiting damping body for wall-like reinforced concrete supporting structures

Abstract: The invention relates to a load-limiting damping body for wall-like reinforced concrete supporting structures, in which an elastoplastic body is arranged between destructible, rigid components. By virtue of the invention, a compact load limiter is provided, which is embedded in horizontal or vertical joints of shear walls and can regulate the load bearing capacity and the damping properties of the shear walls. Using load-limiting damping bodies, it is possible to protect buildings consisting of wall-like supporting structures against shock-like stresses, such as earthquakes or explosions.