Seepage failure by heave in sheeted excavation pits constructed in stratified cohesionless soils

In this study, experimental and numerical investigations are performed to clarify the seepage failure by heave in sheeted excavation pits in stratified cohesionless soils in which a relatively permeable soil layer (k_upper) lies above a less permeable soil layer (k_lower) between excavation base and wall tip. It is shown that the evaluation of base stabilities of excavation pits against seepage failure by using Terzaghi and Peck’s approach leads to considerably lower critical potential differences than those obtained from the model tests. On the other hand, a relatively good agreement is achieved between the results of the model tests and the finite element (FE) analyses. Further investigations are performed by using axisymmetric excavation models with various dimensions and ground conditions, and a comparison between the results obtained from Terzaghi and Peck’s approach and finite element analyses is given.     

考虑截面圆角效应的T型方管相贯节点静力承载力研究

CIDECT的T型方管相贯节点静力承载力公式忽略了弦杆截面圆角效应,有限元计算表明弦杆截面圆角效应对节点极限承载力有一定的影响,尤其对于较大β的节点和弦杆截面圆角外半径较大的冷弯薄壁管材节点的影响更明显。为此将考虑弦杆截面圆角效应,并提出关于T型方管节点静力承载力的修正公式。     

预应力混凝土连续箱梁城市特宽桥试验分析

简要介绍了城市特宽桥的研究现状,通过对一座典型的三跨（30＋45＋30）变截面预应力混凝土连续箱梁城市特宽桥的空间有限元受力分析,并结合荷载试验研究,探讨了城市特宽桥的受力特点和应用前景。     

钢管混凝土柱数值模拟与分析

采用非线性有限元分析方法,进行了钢管混凝土柱轴压状态下的数值模拟及分析。其中钢管采用理想弹塑性本构关系模型,核心混凝土采用约束混凝土本构关系模型。其中分析了6个圆钢管混凝土柱在轴向压力作用下的静力性能,分析结果与试验结果吻合较好,证实了该模型的合理性,可为今后的分析提供一定的参考。     

薄壁筒体承重钢结构高位稳压水箱结构设计

某钢铁厂中厚板热轧工程的给排水系统高位稳压水箱,结构形式为薄壁筒体承重钢结构。结构设计中通过承重结构的方案对比、给排水管的平面布置修改及相应的构造措施,解决结构设计过程中的诸多问题,满足结构受力合理、用钢量省、施工速度快等要求。采用有限元分析软件MIDAS建立高位稳压水箱及基础的整体模型并辅以相关计算,完成结构的相关计算分析。     

半刚性连接组合梁框架足尺模型模拟地震振动台试验

为了研究半刚性连接组合梁框架在地震作用下动力特性以及破坏模式,为半刚性框架抗震设计及在地震区的使用提供依据,进行了1个足尺半刚性连接组合梁框架结构模型振动台试验研究。通过试验,分析了小震、中震和大震作用下半刚性连接组合梁框架结构的动力特性、位移反应、加速度反应、半刚性组合节点内力反应、结构破坏模式。研究结果表明:半刚性连接组合梁框架具有较好的抗震性能,在罕遇地震作用下(1.20g),整体结构仍然没有明显损坏,结构破坏形式为半刚性组合节点和柱脚处产生较大塑性变形,半刚性连接框架结构完全可以在高抗震设防烈度地区使用。对试验框架建立有限元分析模型,进行结构的非线性动力时程分析,计算结果与试验结果较为接近。     

Experiment and FEA of impact resistance of CFST columns with circular cross-section

为研究钢管混凝土柱在侧向冲击荷载作用下的受力性能,通过对圆钢管混凝土柱进行横向落锤冲击试验,获得柱在冲击荷载作用下的破坏形态、整体变形和应变分布规律,分析了冲击力和试件跨中挠度时程曲线的特征;并通过有限元分析,研究了钢材和混凝土强度等参数对圆钢管混凝土柱力学性能的影响。研究结果表明：在试验参数范围内,随着冲击能量的增加,试件冲击力峰值、跨中挠度峰值、冲击持续时间增加;含钢率较大试件的冲击力峰值和冲击力平台值较大,跨中挠度峰值较小、冲击持续时间较短;钢材屈服强度对试件抗冲击性能的影响较大,而混凝土抗压强度对试件抗冲击性能的影响则相对较小。     

Behavior of thick-walled CHS X-joints under cyclic out-of-plane bending

This paper deals with experimental investigations to study the seismic behavior of thick-walled circular hollow section (CHS) X-joints subjected to out-of-plane bending (OPB). Important geometric parameters were varied in designing three full-scale joint specimens in order to evaluate their effect on connection behavior. Test results indicated that the failure modes and the connection efficiency of these joints significantly depended on the brace-to-chord thickness ratio τ and the brace-to-chord diameter ratio β. The tension fracture was identified as a critical failure mode for thick-walled X-joints with large β. CHS X-joints with larger β ratio were found to demonstrate better connection ductility and more satisfactory energy dissipating capacity than those joints with smaller β ratio under cyclic OPB loading. This observation was further verified by the proposed simplified analytical model results. Finite element (FE) analyses were performed to simulate the experimental behavior and facilitate the interpretation of the important test observations.     

混凝土异形柱框架抗震性能的试验研究

以实际工程为背景,对8度区6层异形柱住宅一榀框架的1/3模型进行低周反复加载的拟静力试验,对框架的滞回曲线、骨架曲线、耗能能力、出铰机制、强度与刚度退化等进行分析。结果表明,异形柱框架结构具有较好的抗震性能。对异形柱框架进行有限元分析表明,分析结果与试验结果吻合较好,表明该有限元模型是合理的,可以用于异形柱框架结构的分析研究。