地下与地上钢筋混凝土矩形结构抗震性能对比研究

地下结构由于受周围土体的约束作用,其受力与变形特点与地上结构存在差异。采用Pushover分析方法分别对考虑土-结构相互作用的地下结构和不考虑土体的地上结构的抗震性能进行对比研究,探讨单层单跨和单层双跨钢筋混凝土矩形结构在有、无土体存在时抗震性能的差异。研究表明:考虑土-结构相互作用的地下结构变形能力与无土体时存在差异。在相同结构尺寸与初始轴压比的情况下,考虑土-结构相互作用的地下结构弹性层间位移角限值变小,地下结构更早出现塑性铰;单跨地下结构变形能力比地上结构的差,周围土体的剪切变形约束作用使得地下结构的延性变差;双跨地下结构与地上结构中柱变形能力相差不多,但侧墙的变形能力比地上结构的略差。因此,即使相同尺寸和初始轴压比的钢筋混凝土矩形结构,地上与地下结构的抗震性能仍存在较大差异,地上结构的相关研究成果不宜直接用于地下结构。

Comparative Study on the Seismic Performances of Undergroundvs. Above-Ground Reinforced Concrete Structures withRectangular Cross Sections

The seismic performance of underground structures differs from that of above-ground structures due to the confinement effect of surrounding soil. This paper compares the seismic performances of underground structures, considering soil-structure interaction (SSI), with above-ground structures, without considering soil, by means of the Pushover analysis method. Two kinds of reinforced concrete single-story structures with rectangular cross sections were chosen, including single-span and two-span. The research results showed that the seismic deformation of underground and above-ground structures is different. Under similar conditions, namely, with the same structure size and initial axial compression ratio, the elastic inter-story drift limit of underground structures was less than that of above-ground structures, and the plastic hinge for underground structures appeared earlier. The deformability of the underground single-span structure was weaker because of the shear deformation constraint of the surrounding soil. While the deformability of the central column of the underground two-span structure was nearly the same as that of the above-ground structure, the deformability of the lateral wall of the underground two-span structure was a bit weaker than that of above-ground two-span structure. In conclusion, even with the same structure size and initial axial compression ratio, the seismic performances of underground structures and above-ground structures are different. Therefore, existing research concerning above-ground structures is not applicable to underground structures.