非对称复杂连体结构抗震性能与变形差控制实例研究

以某电厂复杂钢筋混凝土高位汽机厂房和钢结构锅炉厂房构成的非对称复杂连体结构为实例开展抗震性能与变形差控制研究。采用自主开发的COMPONA-MARC三维非线性有限元程序进行弹塑性时程分析,针对单体结构和连体结构的动力特性、弹塑性时程响应、关键构件受力特征和关键层位移差控制指标等进行了详细讨论。结果表明:连体厂房结构可满足规范抗震性能要求和关键层变形差限值的管道设备功能需求;楼板大开洞将引起周围构件横向弯矩显著增大;连体结构一阶振型呈现出与单体结构明显不同的扭转效应,导致部分无楼板约束构件承受较大扭矩;采用分布式单层钢桁架作为厂房间连接构件能有效控制关键层位移差,但会使相邻的主体结构构件承担较大横向弯矩;连接桁架应尽量靠近位移差控制楼层且布置高度均匀,从而减小扭转引起的连接桁架端部杆件受力集中;位移差指标对连接桁架杆件刚度和连接形式不敏感,因此,建议在满足连接杆件承载力和稳定性前提下减小截面尺寸,采用铰接方式,以削弱对主体结构相关构件的影响。

Case study on seismic behavior and displacement differencecontrol of complicated asymmetric connected structures

A case study was conducted on the seismic behavior and deformation difference control of a complicated asymmetric connected structure consisting of a reinforced concrete turbine plant and a steel boiled plant. Based on the elasto-plastic time history analyses with the three-dimensional finite element program COMPONA-MARC developed by the authors, the dynamic characteristics and time-history responses, the mechanical characteristics of key components and displacement differences of the key story of the connected structures were discussed in detail. The analysis results indicate that the structure satisfies the code requirement on seismic performance and the deformation difference of key story is within the limit required by the functionality of pipelines. The absence of floor slab constraint can cause obvious lateral moment in corresponding members. Besides, the first vibration mode of the connected structure is prone to torsion, which is different from the modes of individual structures and leads to significant torques in some beams without slab constraint. The distributed single layer steel tube trusses acting as connectors are able to control the displacement difference of key story effectively but the influence imposed on the main structures is the transverse bending of adjacent members. It is recommended to assign the connecting trusses uniformly along the height and near the key stories, in order to reduce the torsion-induced force concentration of end members in the truss. The displacement difference is insensitive to the stiffness and connection type of the truss. Thus it is also suggested to reduce the section dimension and to choose hinge connection to reduce the impact on main structures, if the demand of capacity and stability can be met.