Showing papers on "Shear wall published in 1999"

Preliminary results and conclusions from the PRESSS five-story precast concrete test Building

Abstract: A large-scale five-story precast concrete building constructed to 60 percent scale was tested under simulated seismic loading as the culmination of the 10-year PRESSS (Precast Seismic Structural Systems) research program. The building comprised four different ductile structural frame systems in one direction of response and a jointed structural wall system in the orthogonal direction. The test structure was subjected to seismic input levels equivalent to at least 50 percent higher than those required for UBC (Uniform Building Code) Seismic Zone 4. The behavior of the structure was extremely satisfactory, with only minimal damage in the shear wall direction, and no significant strength loss in the frame direction, despite being taken to drift levels up to 4.5 percent, more than 100 percent higher than the design drift level. The test validated the Displacement-Based Design (DBD) approach used to determine the required strength and confirmed the low damage and low residual drift expected of the building.

An Overview of the PRESSS Five-Story Precast Test Building

Abstract: At the culmination of the PRESSS (Precast Seismic Structural Systems) research program, a 60 percent scale five-story precast/prestressed concrete building will be tested under simulated seismic loading. This paper describes the prototype buildings used for design and the structural features of the test building. The buildings were designed using the direct displacement based approach, which is able to take advantage of the unique properties of precast/prestressed concrete using dry jointed construction. The test building incorporates four different seismic frame systems in one direction, and a jointed shear wall system in the orthogonal direction. Pretopped double tees are used on three floors, while the other two floors are constructed using topped hollow-core slabs. A major objective of the test program is to develop design guidelines for precast/prestressed concrete seismic systems that are appropriate for use in various seismic zones. These design guidelines can then be incorporated into the appropriate building codes.

Towards cyclic load modeling of reinforced concrete

Abstract: The need for accurate methods of analysis of reinforced concrete structures under general loading conditions has been brought to the fore by structural failures sustained during the Northridge and Kobe earthquakes. This paper presents an alternative method by which finite element analysis procedures can be made to provide accurate simulations of reinforced concrete subjected to reversed cyclic loads. Emphasis is placed on developing simple, numerically stable formulations. Plastic offset strains are defined for concrete and reinforcement, and these are incorporated into the analysis through the use of prestrain forces. The elastic components of strain are then used to define effective secant stiffness factors. To provide a record of plastic offsets, and of maximum strain experienced during previous loading, strain envelopes are defined using a Mohr's circle construction. Provisional constitutive models are presented for the concrete, although further work is required in this area. An analysis of a shearwall shows the procedure to be stable and compliant and to provide reasonably accurate simulations of behavior. The results of a pilot series of panel tests are used to identify the aspects of concrete modeling that are in need of further study and refinement.

Seismic behaviour of steel plate shear walls by shake table testing

Abstract: This dissertation describes an experimental and analytical study on the behaviour of steel plate shear walls with thin unstiffened webs when used as primary lateral load resisting system in mediumand high-rise buildings. The steel plate shear wall system resembles a vertical plate girder where the theoretical buckling strength of the plate panels is negligible and lateral loads are carried through post-buckling strength of the plate panels in combination with the frame action of the surrounding beams and columns. The theory that governs the design of steel plate shear wall structures is essentially the same as that of plate girders developed by Basler in 1961, although the relatively high bending strength and stiffness of the beams and columns have a significant effect on the overall behaviour, especially when high axial forces and overturning effects dominate the behaviour of the system. To verify the guidelines and design principles provided in the latest version of Canada's National Standard on Limit States Design of Steel Structures, CAN/CSA-S16.1-94 (1994), and to broaden the scope of the code, an experimental testing program accompanied by numerical investigation was conducted at the University of British Columbia. This effort was in collaboration with researchers at the University of Alberta and a team of consulting engineers. During the first phase of the experimental program two single storey single bay specimens were tested cyclically to gain information on the general behaviour of the system and verify the adequacy of fabrication procedures. In the second phase, a single bay four-storey 25% scale specimen was tested under a quasi-static cyclic testing protocol. As the third phase of testing, a similar four-storey specimen was tested on the shake table under low, medium and intense dynamic horizontal base motions. The two single storey and one four-storey test specimens were loaded to maximum displacement ductilities of 7 x 8̂ , 6 x 8̂ and 1.6 x 8̂ , during the first and second phases of testing, respectively. The single storey specimens proved to be very stiff, compared to the bare frame, showed good ductility and energy dissipation characteristics, and exhibited stable ii

Shear wall panel

Abstract: A shear wall panel for a building has a rectangular frame of vertical and horizontal members. Inside of the rectangular frame, at least four diagonal members are joined at their ends to create a multi-segmented assembly having at least three vertices and first and second ends and preferably forming a polygon, one of the at least three vertices secured to each of the vertical and an upper horizontal members, the first and second ends secured to a lower horizontal member. The members are preferably of wood and connected together with toothed plates. A lower horizontal member is shear connected to a foundation or laterally stabilized wall or floor below the shear wall panel. Upper strap connectors attach the upper horizontal member to a roof, floor or wall of the building. The upper strap connectors comprises metal straps, a first portion of which have teeth bent out of the metal strap, a second portion of which have holes for nailing through the metal strap into the roof, floor or wall of the building.

Analysis of Repaired Reinforced Concrete Structures

Abstract: A procedure is described by which nonlinear finite-element algorithms can be modified to enable the analysis of repaired or rehabilitated concrete structures, taking into account the chronology of the loading, damage, and repair. The method defines and employs plastic strain offsets in the context of a smeared rotating crack model. The ability to engage and disengage elements at various stages of loading, as well as the ability to carry forward strain measures representing previous loading and damage conditions, are key aspects in the analysis method. Analysis of beams and slabs repaired with fiber-reinforced plastics demonstrates the accuracy of the procedure in accounting for changes in strength, stiffness, ductility, and failure mode as a result of strengthening measures. Flexure-dominated and shear-dominated responses are equally well represented. The analysis of a repaired shear wall, subjected to reversed cyclic loads, illustrates the ability to model severely damaged structures where some portions ...

Cyclic Performance of Perforated Wood Shear Walls with Oversize OSB Panels

Abstract: This paper reports the test results from a study investigating the influence of openings on the lateral resistance of wood-based shear walls built with both standard and oversize oriented strand board panels under monotonic and cyclic loading conditions. Test results showed that the application of nonstandard oversize panels significantly improved the performance of the perforated shear walls compared with standard 1.2 3 2.4 m panels. Door and window openings caused a significant decrease in the strength and stiffness of the walls and precipitated a change in failure mode, especially for walls with oversize panels. Although nail failure modes were commonly observed in walls without openings, a combination of nail and panel failures were observed in shear walls with openings. A newly proposed cyclic test protocol was used that consisted of fewer but more severe displacement excursions, compared with many other test protocols. This was believed to better reflect typical earthquake excitation and avoid low cycle nail fatigue failures, which were observed previously with long sequence cyclic test protocols.

Structural behaviour of sandwich panel shear walls: An experimental analysis

Abstract: Within a comprehensive research project devoted to analyse the contributing effect of cladding panels on the structural behaviour of steel frames under horizontal loads, a suitable experimental procedure has been set up in order to characterise the main behavioural parameters of specific shear walls. In particular, with regard to light-weight sandwich panels, which are currently used in building as enclosure elements, monotonic and cyclic full-scale shear tests have been performed on both single connection specimens and pin-jointed steel frames branced by infill panels. Such an activity, whose main results are summarised in this paper, firstly provides the experimental evidence as basis for setting up numerical and analytical intepretative models. Besides, it supplies useful information on the possibility to use this panel typology as shear wall components. Finally, it points out how their shear performance can be improved through simple modifications of standard prototypes.

Composite structural panel having a face sheet reinforced with a channel stiffener grid

Abstract: A composite structural panel is formed of a single composite face sheet with a stiffener grid adhesively attached to one side of the face sheet. The stiffener grid if formed of an interlocked set of parallel first elongated grid channels extending in a first direction and parallel second elongated grid channels extending in a second direction. Each grid channel is a hollow channel section including two shear walls formed of a shear wall composite material having woven bidirectional shear wall fiber reinforcement cloth embedded in a shear wall matrix, and a cap extending between the top of each of the two shear walls. The cap is formed of a cap composite material of composite material having unidirectional cap fiber reinforcement embedded in a cap matrix, with the unidirectional cap fiber reinforcement extending parallel to the direction of elongation of the grid channel.

Loadbearing Architectural Precast Concrete Wall Panels

Abstract: Architectural precast concrete wall panels that act as loadbearing elements in a building are both a structurally efficient and economical means of transferring floor and roof loads through the structure and into the foundation. In many cases, this integration can also simplify construction and reduce costs. This article presents the many benefits that can be derived from using loadbearing architectural precast concrete walls in buildings. Discussed herein are the various shapes and sizes of wall panels, major design considerations, and when loadbearing or shear wall units should be the first design choice. The role of connections, shear walls, and the use of precast concrete as forms for cast-in-place concrete is explained. In general, the design methods and techniques presented in this article apply to buildings in both seismic and non-seismic areas. The latter part of this article shows how these design principles can be applied in practice in a variety of buildings. These examples illustrate the use of window wall panels, spandrels, and solid or sandwich wall panels as the loadbearing wall members. When all the advantages of using architectural precast concrete as loadbearing walls are added up, it makes good sense to use this structural form in building applications.

Connection of infill panels in steel plate shear walls

Abstract: The behaviour under cyclic loading of unstiffened steel plate shear wall panels at their connection to the bounding beams and columns was investigated on full-size panel corner details. Four different infill panel connection details were tested to examine and compare their response to quasi-static cyclic loading. The load versus displacement response of the details showed gradual and stable deterioration at higher loads. The formation of tears in the connection details did not result in a loss of load-carrying capacity. In addition to the experimental program, a finite element model was developed to model the behaviour of one of the infill plate corner connection specimens. Results from the analysis showed that the finite element method can be used to obtain the load versus displacement behaviour of an infill panel-to-boundary member arrangement.Key words: cyclic loading, hysteresis, shear wall, steel, welded connection.

Concrete-Filled Steel Tubes as Coupling Beams for RC Shear Walls

Abstract: Publisher Summary This chapter explores the use of Concrete-Filled Rectangular Tubes (CFRTs) as coupling beams, and describes an experimental investigation into this form of construction to study their load carrying capacity, ductility, and energy absorption characteristics. In such tubes, the concrete infill prevents the inward buckling of the tube wall, while the steel tube confines the concrete and constrains it from spalling. The combination of steel and concrete in such a manner makes the best use of the properties of both materials and leads to excellent ductility. Eight cantilever beams consisting of two control rectangular hollow section tubes and six CFRTs were tested. All tubes had a wall thickness of 2 mm, with a cross-sectional height of 200 mm and width of 150 mm. The variable for the CFRTs was the concrete strength, designed to cube strengths of 40 MPa ,60 MPa, or 90 MPa. In static loading tests, the specimens were monotonically loaded until failure. The strains and displacements were recorded at different load levels, from which load-deflection curves were plotted. Local buckling was observed on both flanges of all the cyclic test specimens. During load reversal, a buckled flange was straightened again under tension. The compression-tension cyclic stresses caused degradation in both steel and concrete, so that the maximum load reached in a cyclic test is considerably lower than that in the corresponding static test.

The Dynamic Response of Wood‐Frame Shear Walls with Viscoelastic Dampers

Abstract: Results are presented of an experimental investigation, the objectives of which were to evaluate and compare the performance of conventional plywood shear walls with walls that include viscoelastic (VE) dampers. Cyclic tests were conducted on conventional walls and walls with VE dampers; five different damper configurations were tested. The walls with the VE dampers showed an increase in the total energy dissipation and an increase in the effective stiffness, relative to the conventional wall, with increases in energy dissipation as high as 59 percent. Tests demonstrated that the sheathing‐to‐stud and corner dampers can easily be installed within the confines of the wall and can be utilized without impacting the design, construction, or finishing of the shear wall. The results demonstrate that addition of the viscoelastic dampers significantly enhanced the dynamic performance of the walls by increasing the energy dissipation capacity and providing a constant source of energy dissipation.

A quick method for estimating the lateral stiffness of building systems

Abstract: This paper presents a quick method for estimating the lateral stiffness of building structures, including regular and irregular moment frames, braced frames as well as frames with shear walls, which can be used for preliminary analysis and especially final check purposes. The method can be utilized for the calculation of the building displacement at different levels under lateral loads, the contribution of various lateral resisting systems to carrying the lateral loads, and finally the natural frequencies of the system. The basic idea of the method is based on some facts about the lateral deformation and stiffness of building structures, which make it possible to consider an equivalent single-bay single-story frame module for every story of the real multi-bay multi-story frame. This leads to a 3-diagonal or banded stiffness matrix in most cases. Even in the cases resulting in a full stiffness matrix the proposed method does not require solving a system of simultaneous equations for obtaining the lateral displacements. Several numerical examples show the higher efficiency and precision of the proposed method in comparison with the Kan method. The use of the main concepts of the proposed method for preliminary design purposes is also possible as a secondary application. Copyright © 1999 John Wiley & Sons, Ltd.

3128 Modeling of Reinforced Concrete Shear Wall for Nonlinear Analysis

Abstract: A member model of reinforced concrete shear wall with boundary columns and beams was proposed for nonlinear and dynamic frame analysis. The reinforced concrete shear wall was idealized as axial springs for columns and a panel under plane stress states with rigid beams at top and bottom floor levels. Two methods were compared, in which isoparametric element and incompatible rectangular element with four nodes for the panel element were used. The model was verified through the analysis of T-shaped wall tests conducted at Yokohama National University in 1994. The analytical results obtained by the proposed model, such as envelope of loaddisplacement, hysteretic loops, shear and flexural displacement components, showed generally good correlation with the experimental results. Shear deformation was overestimated by isoparametric panel element, whereas incompatible rectangular element, which incorporated flexural deformation by using internal displacements, gave better correlation with the experimental results of flexural yielding walls. For the walls in shear failure, the analytical results were basically same either by isoparametric element or incompatible element.

Post-Peak Cyclic Behavior and Ductility of Reinforced Concrete Columns

Abstract: This study aims to bring into information some important aspects of the inelastic cyclic response of reinforced concrete columns. Here, the behavior of reinforced concrete columns under lateral cyclic loading is studied using a threedimensional finite element analysis program. It consists of path dependent and nonlinear constitutive models representing the stress-strain relationships of the constituent materials. Inelastic material behaviors, such as cover concrete spalling and large lateral deformation of buckled reinforcement, which influence the post-peak inelastic response of RC columns, are modeled and included in the material models. Some experiments conducted by the authors and other researchers are adopted for the verification and discussion of the analytical results. Reasonable agreement between the analytical prediction and the experimental result is observed. In addition, importance of cover concrete spalling and reinforcement buckling is realized and their contribution to the overall post-peak response is assessed. A reinforced concrete column subjected to ground acceleration is analyzed and the seismic response of the column is also discussed. Introduction Recently, performance based design method is being widely discussed for reinforced concrete structures. Structures expected to be exposed to ground motion are designed according to their ductility and for such structures, the post-peak information is required to check the structural performance. Although 2D analysis can satisfactorily predict the response and ductility of pure 2D RC columns and shear walls, 3D analysis is a must for checking seismic performance of 3D RC columns with side reinforcements, the response of which will be over-estimated by 2D analysis. 3D diagonal shear crack profile develops in such columns and 3D crack 1 Graduate Student, Dept. of Civil Engrg., University of Tokyo, Tokyo 113-8656, Japan. 2 Professor, Dept. of Civil Engrg., University of Tokyo, Hongo, Tokyo 113-8656, Japan. analysis is required for reliable prediction of capacity and ductility. Moreover, in order to consider the multidirectional loading due to ground motion also, 3D analysis is inevitable. Reinforced concrete columns subjected to cyclic loading or ground motion often experience high deformation and the load-displacement relationship frequently reaches the post-peak range. From the results of various experiments conducted in the past on laterally loaded reinforced concrete columns, considerable softening phenomenon can be distinguished in the load-displacement relationship in the inelastic region [Fukui et al., 1998]. It has been realized in the past that this inelastic softening behavior is mainly due to the spalling of cover concrete and buckling of longitudinal reinforcement [Suda et al. 1996]. These mechanisms significantly influence the deformation capacity and ductility of the structure. The additional softening, due to spalling of cover concrete and buckling of reinforcement, causes significant difference in the ultimate displacement capacity. Consequently, if this inelastic softening behavior is overlooked in the analysis, the ductility is overestimated. The torsion resistance of RC column is also over-estimated if the diagonal cover concrete spalling is neglected. Hence, the cover spalling and reinforcement buckling should be paid due attention in the analysis. In the past, comparatively more attention was paid to the analytical prediction of pre-peak response and the reliability of post-peak prediction was compromised to a great extent. Through this study, the authors have attempted to understand the material mechanisms involved especially in the inelastic behavior of laterally loaded reinforced concrete columns. In addition, it is tried to enhance the analytical models by simulating and incorporating these highly inelastic material mechanisms in the material constitutive relationships so that the reliability of analytical prediction of inelastic response is improved. In order to achieve the mentioned goals, some lateral loading experiments are conducted on reinforced concrete columns and analyses of those structural members are performed. Analytical Models A three-dimensional finite-element analysis program called COM3 (Concrete Model in 3D), developed in Concrete Laboratory, The University of Tokyo, is used for the analytical prediction of the behavior of RC columns. It includes nonlinear and path-dependent material constitutive models applicable to loading, unloading and reloading conditions as well. They have been verified in the element and member levels with satisfactory results, and have been incorporated in the FEM program for the analysis of reinforced concrete under monotonic and cyclic loading [Okamura and Maekawa 1991]. However, the effect of spalling of cover concrete and the large lateral deformation of reinforcement are not incorporated in the path-dependent nonlinear models. These phenomena can be commonly observed in real structures and small-scale experiments subjected to ground motion. It is thought that these phenomena would have much to do with the inelastic response and should not be ignored especially in analysis of the structures designed for high ductility, as these structures may be subjected to higher strains. In order to study the effect of these mechanisms, the spalling of cover concrete and buckling of reinforcement are modeled and incorporated in COM3 to analyze reinforced concrete columns. FIGURE 1. Formulation of compressive stress-strain relationship of reinforcement Reinforcing bars in RC members, when subjected to high compressive strain, undergo large lateral deformation. This behavior is referred to as buckling of reinforcement and is mainly associated with high geometrical nonlinearity. However, in this study, this mechanism is implicitly incorporated in the material model of reinforcing bars. The formulation of stress-strain relationship of reinforcement fibers START Formulate buckling model for bare bar, σ = Fn(e,L/D,fy) Input D, fy, Es, Et, s, At, le, fc’, ft, ep, Ec, ν Buckling mode, n=1 Calculate axial stiffness of ties, k Calculate required spring stiffness, kn

Full-height buckling of frameworks with cross-bracing.

Abstract: The characteristic deformations and stiffnesses of multistorey frameworks with cross-bracing are established in this paper. Formulae for the shear stiffness of cross-bracing of different geometrical arrangements are presented. The sandwich model is introduced for the full-height buckling analysis. Simple closed-form solutions are derived and a design diagram and tables are given for the calculation of the critical load. Multistorey, multibay frameworks subjected to concentrated top load or uniformly distributed load on the beams are considered, both on pinned and on fixed supports. The results of a detailed accuracy analysis show that the sandwich model is suitable for the stability analysis and the error of the formulae is less than 10%. A worked example is presented to illustrate how the formulae are used for the actual calculation. The geometrical and stiffness characteristics of the example are based on one of the bracing frames of the Cardington steel building constructed in the Building Research Establishment's large building test facility. The technique and formulae presented in this paper are directly applicable to either individual frameworks with cross-bracing or multistorey buildings braced by such frameworks (and shear walls), including the reinforced concrete buildings to be constructed and tested in the Building Research Establishment's large building test facility at Cardington.

Analysis of reinforced concrete coupled shear wall structures

Abstract: The ultimate strength analysis of reinforced concrete coupled shear walls with one or two bands of openings requires a two-stage approach. In the first stage, the analysis of the coupling beams is carried out. This is followed by the analysis of the complete wall in the second stage. A simple approach based on the ‘total moment concept’ for the analysis of coupled shear walls with one or two bands of openings is presented. Experimental results supporting the predictions of the mode of failure and ultimate strength is also presented. This study updates previous research and enhances further understanding of the behaviour of reinforced concrete shear wall structures at ultimate limit states of loading. Copyright © 1999 John Wiley & Sons, Ltd.

An efficient analysis of continuum shear wall models

Abstract: This paper formulates the stiffness matrix and a procedure for the analysis of a general class of coupled shear walls subjected to arbitrary loading and boundary conditions. The computed solutions ...

Seismic Performance of an Existing RC Frame Retrofitted by Precast-Prestressed Concrete Shear Walls : Part 1. Outline of a Specimen and Experimental Results

Abstract: Therefore, it is needed to develop the retrofit method using a precast reinforced concrete shear wall on the surface of existing reinforced concrete frame structure without taking out the mortar in finishing(Fig.1 and Fig.2). That is because the cast-in-place concrete is not used at the existing frame and the strength of the existing frame are increasing by the precast prestressed concrete shear walls