Dissertations / Theses on the topic 'Shear wall openings'

The effect of door and window openings on long timber framed shear walls was the subject of this thesis. Four different wall configurations containing various openings and one control wall with no openings were tested to examine ultimate load capacity and stiffness. All walls were forty feet in length and contained tie-down anchorage at the extreme ends of the wall only. Two replications of the five wall configurations were built. Each of the five wall configurations was tested using a: 1) monotonic displacement pattern and 2) sequential phased displacement pattern. A better understanding of the effect of monotonic and cyclic loading (and the relationship between the two loading types) on ultimate load capacity and stiffness for a given wall configuration were examined. To efficiently design shear walls, the effect of openings on shear wall performance must be known. This thesis adds to previous work on shear walls with openings to provide valuable information for future use. Results from this investigation are intended to provide useful information regarding performance of long shear walls with openings. Data concerning capacity, drift, elastic stiffness, and ductility are presented. Two methods of capacity prediction of shear walls with openings are examined. Sugiyama (1994) provided an empirical equation for prediction of load resistance that has been applied to capacity and is the basis for the perforated shear wall method. This thesis further validates his work to full scale long shear walls. A new method for capacity prediction was developed by the author and is also presented.<br>Master of Science

Construction practices are constantly evolving in order to adapt to physical locations and economic conditions. These adaptations may result in more cost-effective designs, but may also come at a cost of strength. In masonry shear walls, it is becoming more common to reduce the amount of grouting from every cell to only those with reinforcement, a practice known as partial-grouting. Partially-grouted masonry responds differently and in a more complex matter to lateral loads as compared to fully-grouted masonry. The response is made even more complex by wall discontinuities in the form of openings. The main objective of this study is to validate the strut-and-tie procedure for the in-plane lateral strength prediction of partially-grouted, multistory, reinforced concrete masonry walls with openings. The research included testing six three story, half-scale masonry shear walls. Half of the walls had door openings while the other half had window openings. The configurations were selected to represent typical walls in multi-story buildings. The measured lateral strength was compared to estimations from the equations in the US masonry code and to those from an equivalent truss model and a strut-and-tie model. The results show that the U.S. masonry code equations over predicts while the equivalent truss model under predicts the lateral strength of the walls. The results further show that the strut-and-tie model is the most accurate method for lateral strength prediction and is able to account for wall openings and partial-grouting.

碩士<br>國立屏東科技大學<br>森林系<br>90<br>The effects of sizes and amount of opening on the lateral resistance of structural light framing shear wall were under investigation in the study. The walls with the sizes of 2.41 by 3.66 m were framed with 2X4 SPF lumber of grade No. 1 and sheathed with hardwood plywood panels. There is no significant difference in racking strength between wall specimens having window opening less than 120 cm in width and without any opening. The racking strength of wall specimens were reduced about 17.8% and 14.7% for the wall having window openings of 160 cm and 200 cm in width, respectively, as compared to the walls without any opening. The wall having door opening in 80 cm width were 10.5% lower in racking strength than that of without any opening, and 46.8% and 68.5% lower were found for the wall specimens having 200 cm and 280 cm wide door opening, respectively. While no significant difference in racking strength were found for the wall with either double or single window opening, there was 20.8% lower for the wall having double door opening than that of having single opening. The lateral resistance of walls having door opened near load application and at the center of walls showed the similar performance, but a reduction of 13.9% in racking strength were found as the door opened at the far end of load application. The principal strain measured at the corner of 80cm wide window opening when the wall subjected to 350kgf of lateral loads was 50% higher than those measured at the other locations. Furthermore, there were 340% higher in strain measured at the corner of 200cm wide window opening and 80cm wide door opening. The maximum shear strain measured from 80cm wide window opening were 48% higher than the principal strain which were in compression. In the cases of 200cm and 80cm wide window opening, the principal strain was higher than maximum shear strain. The estimated principal stresses for 80cm and 200cm wide window opening of walls were 1.86 and 4.61 times of those walls without any opening. Similarly, it was 5.24 times in principal stress for the wall with 80cm wide door opening. The principal stresses were all higher than the values of maximum shear stresses. The orientation of principal stresses measured near the openings of walls were between 8~15 degrees, while the other location showed among —40~45 degrees. The higher values of horizontal stresses of walls with openings simulated based on the finite element analysis were distributed around the openings which matches the failure mode of the tests. Although the measured strain and stress at the corner of opening of walls were higher than the simulated results, the difference was reduced as the percentage of opening increased. Therefore, it is possible to predict the failure location of wood-framed walls with various openings under lateral loads by using finite element method.

碩士<br>中華大學<br>土木工程學系<br>104<br>The shear wall is one of the reinforcement that commonly used in building structure reinforcement for seismic capability in Taiwan. Building interior will be no exit and cannot receive lighting and ventilation from outside, caused by the complete shear wall. Due to openings of the shear wall, the shear strength of the shear wall will reduce and affect its seismic capability. Using the TRIZ inventive theory to solve the shear wall with opening problems such as technical contradictions, physical contradictions and substance-field analysis to resolve three problems of buildings in shear wall:(1) Shear walls encounter with the conflict and must of lighting , ventilation and exit, how to set up shear walls or have any alternatives;(2) How to increase the seismic capacity (strength) of the shear wall with openings;(3) The shear walls with high windows, how to avoid influence of its structural reinforcement function and short column effect. This study investigated the principles such as nested and parameters change, and the standard solution like to change two substances (S1 and S2) can effectively solve these problems. In order to improve the reinforcing elements of design, the results show that the designer (Architect and Engineer) can use TRIZ theory to solve the problems of the shear wall with openings.

碩士<br>國立屏東科技大學<br>木材工業系<br>92<br>Abstract 【Abstract】The actual sizes of 2.44×3.65 m wood-framed walls were constructed with light-framing approaches in the study, while the wall sheathed with Lauan plywood panels and the frames assembled with SPF structural lumbers. The horizontal shear performance of walls with various opening types subjected to the cyclically lateral load procedures were investigated, and the effect of bracing angles were also included. The results indicated that the racking strength of walls with 120, 160, and 200 cm window openings were only slightly lower than that of the walls subjected to monotonic load application, while the shear stiffness were significantly reduced about 32%, 37%, and 36%, respectively. Similarly, there was 26% lower in shear stiffness for the walls with double 80 cm-wide door openings subjected to cyclically lateral load application. However, both the values of racking strength and shear stiffness for the walls with single 80 cm-wide door opening or 200 cm-wide garage opening were not reduced in comparison to those of walls subjected to monotonic load application. Both the racking strength and shear stiffness of the wood-framed walls with door openings were 23% lower than those of the walls with window openings under the same opening width conditions, and the values of toughness was also 25% lower. The deformation around openings of the wood-framed walls can be improved through the reinforcement at the corners of openings using steel bracing angles. The racking strength and shear stiffness of the walls with double door openings are increased 19% and 30%, respectively, by putting the bracing angles at the corners of openings. The strain energy of the walls with 160 cm-wide and 230 cm-wide window and single door openings increased 11%, 17%, and 17%, respectively. 　　The damping energy and strain energy of walls was reduced as the percentage of opening area increased. The highest damping energy is 90 kgf-m for the wall with 120 cm-wide window opening and the lowest was 54 kgf-m for the wall with 200 cm-wide garage opening. Furthermore, as the shear stiffness of walls increases, the strain energy also increases. The values of coefficient of determination is high between maximum shear stiffness and damping energy or strain energy as the wall reached to the displacement of limit state at failure. The damping energy and strain energy of walls sheathed with gypsum board was the same as the plywood sheathed wall before the lateral displacement stage of 27.2 mm, but the strain energy was lower than that of the plywood sheathed walls due to the tendency of deformation for gypsum board sheathed walls. 　　The values of stress analysis of wood-framed wall with openings by using finite element method showed more accurate in x direction, and deviation in y direction due to the cross grain failure of sheathed panels possibly, which resulted the simulated values higher than the measured values. However, the magnitude of stresses around the corners were still acceptable in accuracy, and the locations of stress concentration were also matched with the actual failure positions at the wall. 【Keyword】Cyclic lateral load, Racking strength, Shear stiffness, Strain energy, Damping energy, Finite element analysis.

碩士<br>國立臺灣科技大學<br>營建工程系<br>90<br>For the existing low-rise RC buildings, the seismic retrofit using the strength of walls is the most economical measure. This study developed a procedure for seismic assessment and retrofitting of the nonductile frame infilled with RC wall with openings. A simple model was developed to predict the shear strengths of RC wall with openings, short column and short beam. Six specimens of nonductile frames infilled with RC walls with symmetric openings had been tested to investigate the failure phenomena among the RC wall with openings, the short column, and short beam. Based on the experimental observation, the flange walls are quite efficient in increasing the shear strength of RC wall with openings. The effectiveness of the wall section between two horizontally aligned openings depends on it’s height-to-width ratio. The wall section atop the door-opening is found to be ineffective in increasing the strength of the wall frame. Finally, better estimations were obtained by the softened strut-and-tie model than that of the ACI 318-02 methed.

碩士<br>國立成功大學<br>建築學系碩博士班<br>100<br>Wing-walls and walls with openings are both incomplete panel within RC frames. In Taiwan, adding wing-walls is a popular seismic retrofit measure, but the wing-walls are usually modeled as columns but not panels in seismic analysis due to their slenderness. The analysis for walls with openings needs case-by-case consideration. It is too complicated so simplified methods such as reduction factors from the size of openings are usually used instead. These mean that practical models for both wing-walls and walls with openings are needed. 　　This research developed an analytical model to estimate the shear strength of RC wing-walls and walls with openings. The analytical model developed from shear-friction concept was originally used for RC shear walls without openings. It calculates the shear strength by simple force equilibrium of the walls with assumed failing path. When it is applied to walls with openings, the failing path must be modified due to the existence of openings. This research proposed the method to determine shear elements and failing paths for wing-walls and walls with openings. Two types of shear element configurations are suggested. The influence of varied axial force on failing path was discussed. However, the comparison with experimental data doesn’t show good result when the varied axial force is considered. Instead, an empirical method is proposed for determining the failing path. 　　Experimental result of 19 walls without openings, 60 walls with openings, and 19 wing-walls were used to verify the analytical model. The preliminary comparison with experimental result shows that the analytical model provides good and conservative estimation for the shear strength of wing-walls and walls without openings, but might be too conservative for walls with openings. Therefore, a revision for walls with openings was made from a detailed study on the errors. It is suggested that among the three modes of shear element-failing path combination proposed, mode A2 should be used when Fsv/Fsh ratio is lower than 2.5 and Mode B is used otherwise. The revised model is verified again and shows good result. Failure modes of the specimens were also compared with the analytical ones. The analytical failure mode is determined by the lesser of the analytical shear strength and flexural strength. The comparison shows accurate prediction for the walls without openings, slight error for walls with openings and conservative result for the wing-walls by mistaking flexural failure as shear failure.

碩士<br>國立臺北科技大學<br>土木工程系土木與防災碩士班<br>106<br>To have natural light and ventilation, old school buildings in Taiwan area were often designed to have many top opening high brick walls infilled within reinforced concrete frames. These brick walls will provide constraints to the adjacent columns and thus the effective lengths of the columns are shortened. Clearly, these short columns will resist more shear loads when compared to the general columns at the same floor and thus they might experience a short column failure. It is very important to accurately predict the shear strength of the top opening brick walls, since it can apply to identify the potential short column failures for the reinforced concrete frames infilled with top opening brick walls. Consequently, a seismic retrofitting project can be conducted for the potential short column failures. It seems that the currently available formula for calculating the shear strength of the top opening brick walls is not applicable to all top opening brick walls. Hence, further investigations of the shear strength of the top opening brick walls are needed. In this work, two reinforced concrete frames infilled with brick walls are cyclically loading tested, where one is a RC frame infilled with a top opening high brick wall and the other is that infilled with a full brick wall. These test results in addition to the previous test results are summarized together to develop a new formula for estimating the shear strength of the top opening brick wall. In this new formula, the high-width ratio of the top opening brick wall and the shear strength contribution from the rupture of brick both are thoroughly considered. Both the cyclic loading test results and the pushover analysis results are applied to derive the new formula. It is believed that the new formula can provide good predictions of the shear strength of a general top opening brick wall.

Research Doctorate - Doctor of Philosophy (PhD)<br>This thesis presents the results of an extensive experimental testing programme of twelve full-scale unreinforced masonry walls with openings subject to in-plane cyclic shear loading in order to simulate seismic loading on in-plane walls typical of Australian unreinforced masonry construction. The walls tested in this study consist of a single leaf of clay brick masonry with a 1:1:6 (Cement: Lime: Sand by volume) mortar. Steel equal angle lintels are used to support the masonry above the wall openings. The twelve wall tests consist of three wall geometry types, two levels of axial precompression, and two repeats of each test. Detailed analysis of the experimental test results is included in this study, and digital image correlation is used to provide detailed insights in to the progression of damage observed during the experimental testing cyclic load histories. Key in-plane wall response parameters for each of the wall tests are obtained from the experimental test results. Detailed material characterisation tests were undertaken during the experimental testing programme to allow for detailed finite element analyses of these wall tests to be undertaken. The experimental test results are replicated using a crack-shear-crush micromodelling approach. Macromodelling of these walls using a total-strain fixed-crack strategy is also undertaken and a sensitivity analysis is undertaken with respect to masonry compressive strength, tensile strength, and elastic modulus. This total-strain fixed-crack macromodelling approach is then extended to replicate a previous experimental study of a two-storey half-scale unreinforced masonry wall subject to in-plane cyclic loads previously tested by the University of Auckland and a sensitivity analysis of the results of this study is undertaken with respect to masonry tensile strength and elastic modulus. Finally, the total-strain fixed-crack macromodelling strategy is extended to replicate the severe damage which was sustained to a three-storey unreinforced masonry building: Avonmore House in the February 22nd 2011 Christchurch earthquake. This is achieved through the use of nonlinear static analyses and then a sensitivity analysis with respect to floor diaphragm stiffness, masonry compressive strength, and masonry tensile strength is undertaken.

碩士<br>國立臺灣大學<br>土木工程學研究所<br>102<br>Lots of elementary and secondary school buildings were damaged by the devastating 921 Chi-Chi earthquake, so scholars proposed methods for increasing the seismic performance of school buildings. Adding shear wall method is a common method to be used in school buildings retrofit. However, by the use of retrofit of adding shear wall, it is difficult to satisfy the lighting and ventilation requirements for school building. Consequently, National Center for Research on Earthquake Engineering (NCREE) planned a series of specimens retrofitted by RC walls with window and door opening to study the feasibility of the proposed method. The specimens were designed according to existing school buildings. In order to comply with existing schools buildings, two common spans, 300 cm and 420 cm, were considered in the experimental plan. This experiment includes eight specimens, which are two bare-frame specimens and six retrofitted specimens. Considering the lighting and ventilation of school buildings, large opening is main principle. Also, the specimen was designed in symmetric configuration, in order to facilitate and establish an effective and reliable seismic evaluation method of RC walls with openings for engineers in the future. Experimental results show that the large-opening specimens can enhance about 3.8 times of lateral strength, at least 13 times of stiffness; the small-opening specimens can enhance about 6.8 times of lateral strength, at least 34 times of stiffness. Drift ratio of all specimens can be up to 2%, it means that the retrofit by RC wall with opening can be applied directly to the low-rise school buildings. The force-displacement curves of all specimens are predicted base on the third-edition Evaluation and Retrofit Handbook for School Buildings. All prediction results are conservative after modification.

碩士<br>國立臺灣科技大學<br>營建工程系<br>91<br>This report provides the experimental and analytical studies on the characteristics of the nonductile reinforced concrete frames and the load deffection relationship of the frames containing walls with openings. Twelve specimens were tested under simulated seismic actions. Test program consisted of three pure RC frame specimens, one nonductile frame infilled with 12cm RC wall, two nonductile frames infilled with brick walls, and six nonductile frames infilled with RC walls with openings. Experimental observations and theoretical analyses indicate that the failure of the RC nonductile frames are dominated by the shear and splice mechanisms, which lack of ductility. The strength of nonductile frames can be increased by the infilled walls (RC of brick), but the lap splices at the column base are harmful to the seismic capacity. The openings create the weak portions in the web which are failed due to shear. Experimental results indicate that the wing walls are effective in enhancing strength. The load-deflection curves of the test specimens can be reasonably predicted by the softened strut-and-tie model.

碩士<br>國立臺灣科技大學<br>營建工程系<br>100<br>In this study. The plane stress and the section force in the structure of the reinforcement. The select shear wall with opening as the analysis model. Sectional force design wall simulation analysis similar to the column structure. Because the section force are axis force、moment and shear force. Therefore in the design section when the first draw to select a reinforced interactive influence diagrams to check whether there is sufficient strength and force of this section of the model can’t express the shear wall by the force after the behavior. Another method for plane-stress method. For analysis of planar structures using the finite element method analysis will stress analysis of data which show the complex stress situation in the area. Reinforced strength of the configuration required for these high-stress areas based on demand by way of analysis. Two different analysis methods produce the results.

碩士<br>國立臺北科技大學<br>土木工程系土木與防災碩士班<br>106<br>Since brick walls were commonly used as compartments in the elementary and the junior high school buildings around the 1970s in Taiwan, accurate evaluation of the shear strength of brick walls is very important. In particular, the top window opening brick wall will generally shorten the effective length of the side columns and thus the shear failure of these side columns might occur. Therefore, the service life of the school buildings can be prolonged if a short column failure can be diagnosed in advance and this weakness is appropriately retrofitted. Because the current shear strength formula for calculating the top window opening brick wall completely ignores the influence of the height of the top window opening brick wall and the rupture of the brick itself, it might significantly underestimate the shear strength of the top window opening brick wall. In a pushover analysis, to underestimate of the shear strength of the top window opening brick wall might cause an early failure of the brick wall and then a possible short column failure cannot be appropriately detected. Consequently, an accurate estimation of the shear strength of the top window opening brick wall can effectively reflect the constraints on the side columns and thus a short column failure can be diagnosed in advance during a pushover analysis. In general, top opening brick walls can be classified into two categories. One is top window opening low brick walls and the other is top window opening high brick walls. The criterion to classify the two categories is based on the critical failure angle of the top window opening brick wall. The diagonal angle of the former category is less than the critical failure angle while that of the second category is greater than the critical failure angle. It seems that the current shear strength formula of the top window opening brick wall can only provide a reliable prediction for low brick walls while for a high brick wall it will underestimate it. Recently, a series of cyclical loading tests have been conducted for reinforced concrete frames infilled with different heights of top opening brick walls so that the shear strength formula for top opening brick walls can be proposed. In this formula, both the height-width ratio of the brick wall and the mechanism of the possible rupture of the brick are considered. Hence, it is anticipated that the proposed formula can give a more reliable prediction of the shear strength of the top window opening brick walls in contrast to the currently available formula. This study will apply both the newly proposed and current shear strength formulas for top opening brick walls to conduct a series of pushover analyses for school buildings located in Taoyuan City. The purpose of this study is intended to address the importance of using the newly proposed shear strength formula for top window opening brick walls so that a short column failure of the side columns can be diagnosed in advance in conducting a pushover analysis. In contrast, it is evident that the application of the current shear strength formula for top window opening brick walls will underestimate the shear strength of the top window opening high brick walls and thus the short column failure of the side columns might not be detected during the pushover analysis. Thus, this will lead to an inaccurate seismic evaluation of a reinforced concrete building. It is manifested from this study that the results highlight the urgent need to update the shear strength formula of existing top window opening brick walls.