Research On Bidirectional Horizontal Seismic Inputs Of Eccentric Structure

As more and more seismic damage we know, we recognized the fact that eccentric structures have the torsion effect under the earthquake function, it is more easy to destroy than symmetrical structures. So it's an important research aspect that how to calculate the response of earthquake and assurance the aseismatic capability of eccentric structures in structure seismic design domain.At the beginning , the background and the development status of the method for the eccentric structure earthquake input is introduced, the analytic method of response spectrum and time-history for the eccentric structure in the domestic and foreign code for seismic design is summarized and can be used for reference. Base on that, the method should be determined that base on the structure the earthquake response under the bidirectional horizontal earthquake inputs and the effect combination method should be close to the response from the structure most disadvantageous angle input is proposed. Several representative eccentric structural models are selected as examples. The structure most disadvantageous direction when the biggest earthquake action effect produces which one direction earthquake input along certain angle with coordinate axis is found out, and the biggest effect value is defined as a normal value. The present commonly method which using bidirectional horizontal earthquake inputs are used to calculate for every example, and the error results relative to the normal value are compared. Some conclusions are obtained as follows:1. It's approximate that the computed result compared with the normal value with the earthquake input method and the effect combination method which stipulated by our country and other national codes, when carries on the bidirectional response spectrum input. But the best two direction proportional control value are 1:0.3, It's closest that the result compared with the earthquake the biggest response which produces from the structure most disadvantageous direction input in several methods.2. It's safe that the computed result with the actual seismic wave two horizontal components proportion value used 1:0.85 of our country's code, when carries on the bidirectional time-history input. But its error is bigger, so the time-history analysis method need advance study.3. It's different that the result of two directions all along the positive direction input and one along the positive another along the negative direction input, when bidirectional input response spectrum or actual seismic wave. Therefore the input direction from two coordinate axis in which the structure have biggest response must be judged beforehand, it's unable to judge if the structure is complex, then the two kind of input directions must be calculated all.