Effect of Tunnel and Building Interaction on the Seismic Response of Building by Numerical Modeling

In building design codes, no attention has been paid to the interaction effect of underground structures and the building, which can change the amount of applied forces on the building. Therefore, in the present study, by using numerical modeling with FLAC 2D software, the effect of tunnel and building interaction on the seismic response of building stories has been investigated in order to have more accurate assessments of seismic forces on the building when we want to design it. In this study, the model was first stimulated in the case of presence of building alone (SF model) by harmonic shear SV waves and the real earthquake waves. Then, by adding a tunnel to the model (STF model), the system was analyzed. By comparing the result of the maximum acceleration of buildings floors in case of STF to the SF model, the effect of tunnel and building interaction on stories acceleration have been investigated. In low frequencies, the negative effect of tunnel on the acceleration response of the building stories was observed. In high frequencies, the positive effect of tunnel on the acceleration of the stories was observed. It was also concluded that the harmonic waves with the frequency equal to the dominant frequency of the real motions, applied to the models, have created more amplification in acceleration response of buildings.