Comparative design of reinforced concrete shear walls.

Abstract

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.