|M.Sc Student||Marzok Ameer|
|Subject||Assessment of the Seismic Capacities of RC Shear Walls|
to Loads and Displacements
|Department||Department of Civil and Environmental Engineering||Supervisors||Professor Avraham Dancygier|
|Professor Oren Lavan|
|Full Thesis text|
Earthquakes can cause a wide range of damage to buildings, including massive cracking, local failures, reduction of structural stability, and failure to structural elements or even total failure of the building.
Reinforced concrete (RC) shear walls are frequently designed by structural engineers in order to withstand seismic loads. These elements are generally designed to develop large displacements, enabling them to dissipate energy under seismic loading.
Estimating the ultimate displacement capacity of RC shear walls can be a difficult challenge for engineers because of the non-linear behavior of this composite structure, which is made of cracked concrete and yielding steel. Various numerical methods, computer programs and simplified equations have been developed in order to estimate the ultimate lateral load and displacement capacities of RC shear walls subjected to seismic action. However, different methods yield different estimations of these capacities.
This study deals with the evaluation of the displacement and load capacities of RC shear walls. In the first part of the work, some of the most used methods and programs were examined and compared with published experimental data. Additionally, a non-linear direct calculation procedure (NLDC) was developed in this work and its predictions were also compared to the experimental data. The behavior of twelve published experimental shear walls was compared with the results obtained from seven different computer programs and calculation procedures: NLDC, Response2000, VecTor2, OpenSEES, SAP2000, ATENA3D and IDARC. The largest normalized errors (as defined in the Thesis) in calculating the displacement capacities using OpenSEES, SAP2000, VecTor2, Response2000, ATENA3D, NLDC and IDARC were 0.39, 0.48, 0.53, 0.56, 0.79, 0.87 and 0.94, respectively. However, the smallest average of the normalized errors in calculating the displacement capacity was achieved by using Response2000 and OpenSEES. The largest errors in calculating the moment capacity using NLDC, VecTor2, Response2000, OpenSEES, IDARC, ATENA3D and SAP2000 were 10%, 11%, 12%, 12%, 12%, 18% and 19% (respectively), where the smallest average of the errors in estimating the moment capacities was achieved by using the NLDC procedure.
The second part of the thesis comprises development of a simplified model to predict the load capacity of RC shear walls. This model has been developed in view of the relatively complex procedure, which is required for a detailed estimation. Calibration of the model parameters is based on numerous results that were computed by the non-linear NLDC procedure. A simple equation for approximating the moment capacity of RC sections with distributed reinforcement was developed and it showed very good agreement with experimental results, where the largest error was only 10%.
Finally, the effect of the reinforcement type (yield strength and ductility class) on the behavior of RC shear wall has been examined by analysis of case studies. This part of the study has shown that using type C 500-MPa rebars in shear walls, whose failure is controlled by yielding of the tension reinforcement, leads to reduction of only 14-17% in the displacement capacity, compared with walls that include the higher type C 500-MPa rebars.