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>Displacement based design of reinforced concrete structural walls: An experimental investigation of walls with rectangular and T-shaped cross-sections.
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Displacement based design of reinforced concrete structural walls: An experimental investigation of walls with rectangular and T-shaped cross-sections.
This report summarizes results of an experimental and analytical study of reinforced concrete structural walls with symmetrical and unsymmetrical cross-sections, designed using a displacement-based design methodology. The primary objectives of this research were to assess the ability of using a displacement-based approach for design of reinforced concrete structural walls and to study the behavior of unsymmetrical "flanged" structural walls.; Four, approximately quarter-scale, structural wall specimens were constructed and tested under constant axial stress and reversed cyclic lateral loads. Two of the specimens had rectangular cross-sections, whereas the other two had T-shaped cross-sections. Typical material properties were used for all four specimens (grade 60 reinforcing steel and 4,000 psi concrete). The primary variables of the testing program were: (1) the shape of the wall cross-sections, (2) the spacing and configuration of the transverse reinforcement, and (3) the distribution of the vertical and horizontal web reinforcement.; Experimental results reveal that the rectangular walls exhibit stable, hysteretic behavior and possess excellent ductility and energy absorbing capabilities. Based on the results of the rectangular walls, it is concluded that current code requirements (UBC-91, ACI 318-89) for the design of symmetrically shaped structural walls often result in overly conservative designs which should be relaxed to make the use of these walls more economical. UBC-91 does not provide guidelines which specifically address the design of unsymmetrical "flanged" structural walls which may exhibit brittle behavior, if not detailed properly. Results of the T-shaped walls indicate, that when properly detailed (using the proposed displacement-based design procedure), these "flanged" walls can exhibit excellent behavior (ductile, hysteretic response) similar to that of the rectangular wall specimens; however, an accurate assessment of the effective flange width is essential.; The analytical studies that were conducted focused on using basic principles and existing monotonic modeling techniques for predicting the cyclic behavior of structural walls. Analytical studies were conducted to predict: (1) flexural-strength, (2) shear-strength, (3) stiffness, (4) ductility, and (5) buckling of longitudinal reinforcement. Excellent correlation is observed between the analytically predicted behavior and the experimentally measured results, indicating that monotonic modeling techniques provide an effective method for predicting cyclic behavior of structural walls.; Based on results of this study it is concluded that the recommended displacement-based design procedure is a simple, yet effective design technique that can be used to design slender structural walls with any combination of cross-section and reinforcing details. Use of this procedure results in structural wall designs that are directly related to the building attributes as well as the wall attributes, and often results in structural walls that require substantially less transverse reinforcement than required by current codes.
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