Combinación de componentes horizontales de registros sísmicos considerando la dirección y tiempo donde se producen las aceleraciones máximas. Comparación con el método de combinación espectral SRSS (ASCE 7).

Abstract

This work presents a new methodology to combine the horizontal components of seismic records. The new methodology takes into consideration the time and the direction where the maximum values of the response occur.As part of this thesis, an algorithm was developed in Matlab and it was utilized to calculate the combination of the horizontal components of records. The algorithm calculates the dynamic response (accelera tion, velocity and displacement) based on the Newmark linear acceleration method (Chopra 2014) for each direction and combines them in time. In order to construct the spectrum, the algorithm determines the maximum value of the response that is already combined for each natural period of vibration. The results of the proposed method were compared against the results obtained from the SRSS method, which is specified in the ASCE 7, by means of the factor F. The factor F is defined as the ratio of the response obtained by the SRSS method and the response based on the proposed methodology in this study. The results were evaluated based on the F factors for the following cases: • PGA of the combination of records. • Maximum difference of the response of displacement between both methods. • The average of the F factors of the absolute acceleration response spectrum between periods 0 to 5.0 sec, at intervals of 0.05 sec. The records were classified according to their PGA and the distance from the seismographic station to the fault to determine if these parameters influence the differences found between the combination methods of records. Finally, we studied cases where the greatest differences were found between the methods and the cases where both methods give simila r answers.