Ductility and Ultimate Capacity of Concrete-Filled Lattice Rectangular Steel Tube Columns

A kind of concrete-filled lattice rectangular steel tube(CFLRST)column was put forward.The numerical simulation was modeled to analyze the mechanical characteristic of CFLRST column.By comparing the load-deformation curves from the test results,the rationality and reliability of the finite element model has been confirmed,moreover,the change of the section stiffness and stress in the forcing process and the ultimate bearing capacity of the column were analyzed.Based on the model,the comparison of ultimate bearing capacity and ductility between CFLRST column and reinforced concrete(RC)column were also analyzed.The results of the finite element analysis show that the loading process of CFLRST column consists of elastic stage,yield stage and failure stage.The failure modes are mainly strength failure and failure of elastoplastic instability.CFLRST column has higher bearing capacities in comparison with reinforced concrete columns with the same steel ratio.In addition,the stiffness degeneration of CFLRST column is slower than RC column and CFLRST column has good ductility.

Natural Vibration Characteristics for Prestressed Concrete-Filled Rectangular Steel Tube Simply Supported Beam

The dynamic control equation of a new prestressed partially concrete-filled rectangular steel tube(CFRT)beam can be derived based on D’Alembert’s principle.It is used to infer the theoretical results of the dynamic characteristics for the prestressed CFRT beam.Additionally,the finite element model is set up by ABAQUS for simulation analysis.The results show that the natural vibration frequencies and mode function of the prestressed CFRT simply supported beam calculated by the theoretical formulas are reliable since the relative errors of the first-order frequencies under different prestressing levels are within 6%compared with the finite element results.Further analysis of the prestressing parameters is carried out using the theoretical formulas,in which factors such as the prestressing level,eccentricity of tendons,and tensile stiffness of prestressed tendons have different influences on the natural vibration frequencies.Finally,it provides a theoretical basis for the dynamic design of the prestressed CFRT beams.

Push-Over Analysis of the Seismic Behavior of a Concrete-Filled Rectangular Tubular Frame Structure

To investigate the seismic behavior of concrete-filled rectangular steel tube （CFRT） structures, a push-over analysis of a 10-story moment resisting frame （MRF） composed of CFRT columns and steel beams was conducted. The results show that push-over analysis is sensitive to the lateral load patterns, so the use of at least two load patterns that are expected to bound the inertia force distributions is recommended. The M-Ф curves and N-M interaction surfaces of the CFRT columns calculated either by Han＇s formulae or by the USC-RC program （reinforced concrete program put forward by University of Southern Califonia） are suitable for future push-over analyses of CFRT structures. The P-A effect affects the MRF seismic behavior seriously, and so should be taken into account in MRF seismic analysis. In addition, three kinds of RC structures were analyzed to allow a comparison of the earthquake resistance behavior of CFRT structures and RC structures. The results show that the ductility and seismic performance of CFRT structures are superior to those of RC structures. Consequently, CFRT structures are recommended in seismic regions.

矩形钢管混凝土柱受力性能关键影响参数研究进展

介绍了国内外矩形钢管混凝土柱受力性能关键影响因素的研究进展,主要包括钢管板件局部屈曲行为、混凝土横向约束效应、加劲肋设置、钢管和混凝土间的界面抗剪强度及混凝土的收缩和徐变五个方面,指出了矩形钢管混凝土柱需进一步研究的方向。

东直门交通枢纽暨东华国际广场商务区公交场站结构初步设计

通过对东直门交通枢纽暨东华国际广场商务区公交场站结构初步设计的介绍,从地上结构体系如何确定、屋面楼板方案如何选择、结构体形超长的问题等几方面分析比较,得出较为科学的结构方案,为今后同类项目的设计提供参考。