深圳岗厦北交通枢纽超大跨地下中庭结构方案研究

Research on structural system of super large span underground atrium of Shenzhen Gangxia North transportation hub

深圳岗厦北交通枢纽中庭结构跨度51.2m×48m,是远超常规的大型明挖地下结构;通过方案比选,确定采用主要受力构件为钢-混凝土组合梁和大直径钢管混凝土柱的平板正交主次梁框架结构体系。计算了中庭大跨结构在各种工况下的受力,验算了结构的承载力、位移、裂缝宽度等指标;分析了结构在分别拆除五种关键受力构件时的受力,评估了结构的抗连续倒塌性能;建立了大跨结构模型,对比了结构在无防火保护和采用防火措施下的抗火表现;分析了站桥合建关键转换梁节点受力状况;比较了4个临时支撑布置方案,核验了施工阶段结构内力。结果表明,结构在三向地震作用下的力学响应满足设计要求;关键受力构件失效后仍具有较高的剩余承载力;采取设计抗火方案后结构的抗火性能满足要求;关键转换梁节点构造合理,受力性能良好;按比选后方案设置的临时支撑可以显著降低施工阶段的内力,施工阶段的受力满足要求。结构设计合理,性能优良。

The atrium structure span of Shenzhen Gangxia North transportation hub is 512m×48m,which is far beyond the span of conventional large open cut underground structure.Through scheme comparison and selection,it is determined that the structural system is flat orthogonal primary and secondary beam frame and the main bearing members are steel-concrete composite beams and large-diameter concrete-filled steel tubular columns.The bearing capacity,displacement and crack width of the atrium large-span structure under various working conditions were calculated;the stress of the structure was analyzed when the five key components were removed,the anti-collapse performance of the structure was evaluated;a large-span structure model was established,and the fire resistance performance of the structure without fire protection and with fire protection measures was compared;the stress state of the transfer beam joint built by the station and bridge was simulated;four temporary support layout schemes were compared,the internal force of the structure in the construction stage was verified.The results show that the structure has good mechanical response under three-dimensional earthquake;after the failure of key bearing members,they still have high residual bearing capacity;the fire resistance performance of the structure meets the requirements after the fire resistance scheme is adopted;the transfer beam joint has reasonable structure and good mechanical performance;the temporary support set according to the scheme after comparison and selection can significantly reduce the internal force in the construction stage,and the stress in the construction stage can meet the requirements.The structure design is reasonable and the performance is excellent.