Abstract: In valleys buildings are commonly tightly located. However, the interaction between sedimentary valley and compact buildings under ground motion is currently not clear. Therefore, in this paper, the indirect boundary element method (IBEM) is used to analyze the valley-buildings effect under the plane SV waves. The results show that there exists significant and complex dynamic interaction between the sedimentary valley and buildings, and the seismic response of the buildings in the valley illustrates rapid alternation of strong and weak amplitude. The interaction characteristics strongly depend on the crucial factors such as incident angle of seismic wave, sedimentary valley group of medium and depth of the sedimentary valley. Overall, the buildings group has a large effect on the seismic response of shallow alluvial valley, and the seismic response can decrease by 50% for high-frequency wave incidence. It’s necessary to consider the effect of the buildings when we evaluate the seismic amplification effect in the actual valley, and the anti-seismic design standard of the buildings located at the focus of seismic waves should be properly improved.

Key words: city-site effect, sedimentary valley, buildings, seismic wave, indirect boundary element method (IBEM)