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چكيده انگليسي :

Strut and Tie Modeling For Boundary Elements of RC Shear Walls with Openings Parsa Asgariyan p asgariyan@cv iut ac ir January 9 2012 Civil Engineering Department Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Davood mostofinejad email address dmostofi@cc iut ac irAbstractRC shear walls are one of the lateral load resisting systems in concrete structures that are widely used due totheir proper seismic performance In many cases shear walls contain openings due to architectural purposes including doors and windows or crossing with mechanical and electrical installations Openings in wallssignificantly influence their behavior such as changing their force transfer mechanism reducing theirstrength stiffness and ductility level Design by strut and tie models STM is an emerging method thatsimultaneously considers shear forces bending and torsional moments providing appropriate and optimumdesign for structures These models replace the structure with a simple truss although several models can beconsidered for more complex structures According to the effects of strut and tie model on the behavior of astructure it is very impressive to find the best truss in accordance with the principal internal structural stress Boundary elements of shear walls are parts of the walls edges or edges of the openings that significantlystrengthen longitudinal and transverse reinforcements Boundary elements significantly affect on the strengthand ductility of shear walls Thus considering the boundary elements is an important step to improve thebehavior of shear walls The objective of the present research is to study the strut and tie models in 5 shearwalls with openings and investigate effects of boundary element of shear wall in STM Two strut and tiemodels with their associated boundary elements are considered to investigate effects of boundary elements onthe behavior of shear wall with openings a strut and tie that the designer considers and the other modelwhich can be achieved from topology optimization In order to realize the performance of strut and tiemodels shear walls are designed according to the conventional method in ACI 318 08 and are comparedwith the strut and tie method For better compression of design methods the same amount of reinforcementis used Total volume of transverse and longitudinal reinforcement used for the wall designed by STMmethod is identical with total volume of transverse and longitudinal reinforcement used for the wall designedby conventional method of ACI 318 08 To study the behavior of RC shear wall FEM nonlinear program isused Comparative result of the FEM and experimental behavior of RC shear wall is used and it can beconcluded that the FEM results using damage plasticity and tension stiffening effects are in close agreementwith the experimental ones It can be seen from the results that shear wall designed using strut and tie modelsshows better behavior than the wall designed with ACI 318 08 The results also show that boundary elementsin shear wall have improved the final capacity and ductility of shear walls The wall ductility is affected bytwo important components transverse reinforcement in boundary elements and longitudinal reinforcementsat wall edges The former improves ductility due to confinement although the latter might decrease it Implementation of boundary elements in the proposed STM method leads to higher strength and ductility incomparison with ACI 318 08 approach Key wordsStrut and tie STM RC Shear wall Boundary elements of shear wall Topologyoptimization

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