Academic literature on the topic 'Shear walls'

The main objective of the study is to verify the accuracy of the approximate hand calculation method used extensively by the engineers for the calculation of the rigidity of shear walls with openings. Different types of shear walls are considered varying in the dimensions and positions of the opening, however, maintaining the same basic material properties. The results obtained by the hand calculation are compared to the finite element approach to check for the discrepancy. The finite element analysis software NISA/DISPLAY IV and SAP2000 is considered for the purpose.

The research in this dissertation is divided between three different approaches for predicting the shear strength of reinforcement masonry shear walls. Each approach provides increasing accuracy and precision in predicting the shear strength of masonry walls. The three approaches were developed or validated using data from 353 wall tests that have been conducted over the past half century. The data were collected, scrutinized, and synthesized using principles of meta-analysis. Predictions made with current Masonry Standards Joint Committee (MSJC) shear strength equation are unconservative and show a higher degree of variation for partially-grouted walls. The first approach modifies the existing MSJC equation to account for the differences in nominal strength and uncertainty between fully- and partially-grouted walls. The second approach develops a new shear strength equation developed to perform equally well for both fully- and partially-grouted walls to replace and improve upon the current MSJC equation. The third approach develops a methodology for creating strut-and-tie models to analyze or design masonry shear walls. It was discovered that strut-and-tie modeling theory provides the best description of masonry shear wall strength and performance. The masonry strength itself provides the greatest contribution to the overall shear capacity of the wall and can be represented as diagonal compression struts traveling from the top of the wall to the compression toe. The shear strength of masonry wall is inversely related to the shear span ratio of the wall. Axial load contributes to shear strength, but to a lesser degree than what has been previously believed. The prevailing theory about the contribution of horizontal shear reinforcement was shown to not be correct and the contribution is much smaller than was originally assumed by researchers. Horizontal shear reinforcement principally acts by resisting diagonal tensile forces in the masonry and by helping to redistribute stresses in a cracked masonry panel. Vertical reinforcement was shown to have an effect on shear strength by precluding overturning of the masonry panel and by providing vertical anchorages to the diagonal struts.

Thesis (M.S. in civil engineering)--Washington State University, May 2010.<br>Title from PDF title page (viewed on July 21, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 96-97).

<p>Wind loads acting on wooden building structures need to be dealt with adequately in order to ensure that neither the serviceability limit state nor the ultimate limit state is exceeded. For the structural designer of tall buildings, avoiding the possibly serious consequences of heavy wind loading while taking account at the same time of the effects of gravitation can be a real challenge. Wind loads are usually no major problem for low buildings, such as one- to two-storey timber structures involving ordinary walls made by nailing or screwing sheets of various types to the frame, but when taller structures are designed and built, serious problems may arise.</p><p>Since wind speed and thus wind pressure increases with height above the ground and the shear forces transmitted by the walls increase accordingly, storey by storey, considerable efforts can be needed to handle the strong horizontal shear forces that are exerted on the bottom floor in particular. The strong uplift forces that can develop on the wind side of a structure are yet another matter that can be critical. Accordingly, a structure needs to be anchored to the substrate or to the ground by connections that are properly designed. Since the calculated uplift forces depend very much upon the models employed, the choice of models and simplifications in the analysis that are undertaken also need to be considered carefully.</p><p>The present licentiate thesis addresses questions of how wind loads acting on multi-storey timber buildings can be best dealt with and calculated for in the structural design of such buildings. The conventional use of sheathing either nailed or screwed to a timber framework is considered, together with other methods of stabilizing timber structures. Alternative ways of using solid timber elements for stabilization are also of special interest.</p><p>The finite element method was employed in simulating the structural behaviour of stabilizing units. A study was carried out of walls in which sheathing was nailed onto a timber frame. Different structural levels were involved, extending from modelling the performance of a single fastener and of the connection of the sheathing to frame, to the use of models of this sort for studying the overall structural behaviour of wall elements that possess a stabilizing function. The results of models used for simulating different load cases for walls agreed reasonably well with experimental test results. The structural properties of the fasteners binding the sheathing to the frame, as well as of the connections between the members of the frame were shown to have a strong effect on the simulated behaviour of shear wall units.</p><p>Regarding solid wall panels, it was concluded that walls with a high level of both stiffness and strength can be produced by use of such panels, and also that the connections between the solid wall panels can be designed in such a way that the shear forces involved are effectively transmitted from one panel to the next.</p>

This thesis describes three numerical models, developed by the author, that predict the behavior of timber shear walls. Two of the models have been implemented in finite element programs. One program predicts the static behavior of shear walls and the other predicts the dynamic response to earthquakes. Both programs incorporate 1) the ability to predict the ultimate load capacity of the walls, 2) the effects of bearing between adjacent sheathing panels, 3) the effects of bending in the sheathing, and 4) the effect of bearing and gap formation between framing elements. The third model is a closed form mathematical model that was developed to predict the steady state response of shear walls to harmonic base excitations. A series of experimental tests were performed to determine the load-deflection characteristics of single nail connections between the solid wood, used for framing, and sheathing materials. The load-deflection characteristics for these connections were used to predict the behavior of timber shear walls using the finite element models. An extensive experimental program, consisting of five different tests and forty-two full size shear wall specimens, was conducted to verify the three numerical models. The experimental program included a new test that is representative of the earthquake loading for a ground floor wall of a three-storey North American apartment building. The test results were also used to: 1) compare the performance of waferboard with that of plywood sheathing, 2) investigate the dynamic behavior of shear walls, 3) investigate effects of out-of-plane deflections of the sheathing, and 4) examine the anchoring connection that resists the overturning moment. The merits and shortcomings of the five shear wall tests are discussed, along with their future usefulness in determining the effects of changes in the construction techniques used for timber shear walls. The dynamic model and shear wall test results are then used to investigate four design codes to see if shear walls, designed according to the various codes, adequately resist the loads experienced during earthquakes. A resistance factor for the design of shear walls is recommended for inclusion in the 1990 Canadian timber design code. The recommended resistance factor will result in the design loads specified by the code being more representative of the loads generated during an earthquake. Three important construction details are also discussed to inform the reader of possible problems that can be expected if these details are neglected during either design or construction. The details are: the hold-down anchor, framing corner connection, and sheathing connector. Finally, recommendations are made as to the type of research that is required to develop a design procedure for timber shear walls, based on the actual dynamic characteristics of shear walls as well as reliability theory.<br>Applied Science, Faculty of<br>Civil Engineering, Department of<br>Graduate

Code provisions for the determination of earthquake loads are intended to give reasonable estimate of the lateral forces that occur on a building as a result of an earthquake. Two major steps can be described in the procedure: the calculation of the base shear based on both the characteristics of the earthquake and the building, and the distribution of the base shear over the stories and the resisting earthquake elements of the building. Reinforced concrete ductile shear walls are the earthquake resisting elements considered in this study. Code provisions for the design of reinforced concrete ductile shear walls are intended to provide adequate reinforcement details and concrete strength to permit inelastic response under major earthquakes without critical damage or collapse. The objective of this study is to provide, using an assumed building in Victoria, British Columbia, detailed description of the design procedures used by different design codes, and to compare the results obtained on the earthquake loads determination and on the reinforcement details provided to the shear walls. The NBCC-1995 and the IBC-2000 design code procedures were used to determine the earthquake design loads in Chapter 2, and the ACI318-99, the CSA-1995 and the NZS-1995 were used to design a reinforced concrete shear wall in Chapter 3. Comparative conclusions are presented Chapter 4. Generally, design of reinforced concrete shear walls using Canadian, American, and New Zealand provisions should be done based on the earthquake loads obtained from code provisions of Canada, the United States, and New Zealand, namely the comprehensive provisions of NBCC-1995/CSA23.3-94, IBC-200/ACI318-99, and NZS:3101:1995 respectively. However, it was necessary in this study to use the same loads in the different reinforced concrete shear wall design procedures in order to make comparative conclusions more effective. Therefore, the earthquake loads obtained from NBCC-1995 provisions were exclusively used to do the three different design procedures of reinforced concrete design using the code provisions of ACI318-99, CSA23.3-94, and NZS:3101:part 1:1995 respectively. The choice was based on the fact that the location of the building is in Canada. The fundamental assumptions that were made in this study include that: the building, described in Section 2.2, is be braced by reinforced concrete ductile shear wall systems, which means that the shear walls resisting system will resist 100% of the lateral forces resulting from an earthquake. The shear wall considered in the design has adequate foundation able to transmit 100% of all structural actions to the ground.