The State of Knowledge and Practice in Concrete Structure Design for Earthquake

Abstract

The duty of structural engineers is to design and build structures or buildings (1) that are safe, (2) that provide comfort to occupants during strong winds or earthquakes, and (3) that will result in the least construction cost and the most savings to building owners. The state of knowledge is that research has developed nonlinear response history analysis (NRHA) method for predicting the behavior (response) of reinforced concrete structures subjected to winds or earthquake ground motions from reinforcing steel yielding at critical sections to structural member (beam, column, connection, slab, and wall) failures up to partial or the whole structural system collapse. Some of the NRHA methods have been verified by shake table dynamic testing. The state of practice for the design of important structures whose failures could cause significant casualty of people’s life has been using NRHA for seismic and wind analyses and to ensure the safety of these buildings and to provide comfort to occupants and savings to building owners. Buildings have been designed and built worldwide using NRHA successively. And local jurisdictions (building departments) in the United States and China and other countries have required NRHA to be performed for high-rise buildings. NRHA is inherently complicated and complex because it involves earthquake ground motions which are random, in conjunction with nonlinear structural analyses due to the decreasing stiffness and increasing damping values of a structure resulting from concrete cracking and steel yielding at each time step of earthquake ground motions. Therefore, knowledge in the NRHA method and understanding of its proper use are essential. The way to gain that knowledge and understanding is timely sowing seeds in a good ground that will reap rich harvest. The proper use of NRHA enables structural engineers to design and build safer and better buildings with less construction cost than buildings without using the NRHA method against environmental hazards, such as earthquakes or winds. The same principle of timely sowing seeds in a good ground is also applicable to building a better and more resilient family structure against environmental hazards, such as drugs or violence, and we must do it timely because time flies.