Experimental Study on Seismic Behavior of Penetrated Interior Diaphragm on One Side Beam-to-Column Connection for Concrete-Filled Square Steel Tube

A total of three experimental specimens of penetrated interior diaphragm on one side had been tested under low-cyclic reversed loading to study the hysteric behavior,strength and stiffness degradation,ductility,energy dissipation capacity and the failure modes.The only difference of all specimens was the axial compression ratio.Experimental results show that the story drift ductility ratios are 2.11~2.32,and the energy dissipation ratios are 1.141~1.502 at the peak load.Additional anti-seismic design and research recommendations are presented.     

Numerical Method for Load Bearing Capacity of High Strength Steel Columns at Elevated Temperature

In order to make fire resistance design of high strength steel columns in building structures, the numerical calculation method on load bearing capacity of high strength steel columns at elevated temperature was investigated. By taking the mechanical property of high strength steel at elevated temperature into consideration, extension was made on the inverse calculation segment length method and the program to compute the load bearing capacity of high strength steel columns at elevated temperature was performed. The program was adopted to compute the load bearing capacity. The results obtained by the program and the finite element analysis were compared and good agreement had been found. The influence of magnitude, distribution mode of residual stress and initial geometry imperfection on ultimate load bearing capacity was analyzed by employing the program. It is shown that the extended method can be is shown used to calculate the load bearing capacity of high strength steel columns at elevated temperature; the magnitude and distribution mode of residual stress had little influence but the geometry imperfection have significant influence on ultimate load bearing capacity.     

Factors Affecting the Ultimate Bearing Capacity of Cold-Formed Steel Portal Frames

The FEM simulation analysis method was studied to identify the ultimate bearing capacity of cold-formed steel portal frames.In this study,the beam-spring system was used to simulate the performance of joints.The initial imperfection of frame components was considered.The deformation performance and failure features of portal frame structures under vertical loads also were studied.The analytic results of the FEM simulation analysis method are close to the values obtained by experimentation.The ultimate bearing capacity of portal frames were computed by changing parameters such as the web plate thickness,the flange width,the plate thickness of brackets,the portal frame roof inclination,and the column footing stiffness.The analytic results indicate that the ultimate bearing capacity may be improved when the parameters mentioned above are increased.     

Analysis on the Behavior of Diaphragm Through Connection between Steel Beam and Concrete-filled Steel Tubular Column

Diaphragm through connection is a new kind of connection between steel beam and concrete-filled steel tubular column. Quasi-static test and numerical simulation had been carried out to investigate the behaviors of diaphragm through connection used in Zhonghai Square. The results show that, the bearing capacity, rigid and ductility of the diaphragm through connection are excellent, and the seismic principle, i.e., ‘strong column but weak beam’ and ‘strong connection but weak component’, is reached. The numerical model of diaphragm through connection was provided, and the results drawn from the model agreed with the test results. Influences of diaphragm dimension on the behaviors of the diaphragm through connection with praposed the numerical model had been investigated, and the design suggestion was provided based on the analysis.     

Calculation Methods for Steel Frame Structure Based on the Structural Ultimate Bearing Capacity

The existing problems in calculation approach for multi-story and high-rise steel frame structure are summarized. As the shearing deformation is considered, the analysis methods for steel frame structure are put forward based on the structural ultimate bearing capacity, which is on the basis of second order inelasticity analysis for steel structure. In the approach, the tangent module brought forward by Bleich, F. is used, the second-order refined plastic hinge method presented by Liew, J. Y. R. is modified.     

Critical Temperature of Axially Restrained Steel Columns withPartial Fire Retardant Coating Damage

In order to investigate the fire resistance of steel columns with partial fire retardant coating damage in fire, based on the differential equation of equilibrium on each portion of steel column, the deflection of steel column after the fire retardant coating damage was derived, with the pined ends and rigid ends of the columns at elevated temperatures. The critical temperature calculation method was proposed for partial fire protection damage and axial restrained steel columns by taking the edge yielding criteria. The deflection and axial displacement were verified by finite element method at elevated temperature. With a case study, the critical temperature and relationship of axial force and temperature were obtained for pined column with axial restraint. It was shown that the axial force of the steel column at elevated temperatures was increased and the critical temperature was decreased by the axial restraint. The longer the fire retardant coating damage was and the higher the axial restraint was, the lower the critical temperature was.     

Axial Bearing Capacity Design Method of Cold-Formed Steel Quadruple-C Built-up Section Members

The finite element model involving geometric large deformation,materials and contact nonlinearity is established.Specimens of cold-formed steel quadruple-C built-up section members are simulated and the finite element models are proved to be valid.Then,numerical analysis on the behavior of specimens with different slenderness ratio and flange flakiness ratio are carried out,and then the axial bearing capacities of specimens are obtained.Based on effective width method and direct strength method (DSM) in related codes,two design methods of cold-formed steel quadruple-C built-up section members under axial compression are proposed:effective length method and correction factor method.It is shown that:the final failure characteristics of all specimens are local buckling and distortional buckling.In the case of not considering the reduction of effective length,the results calculated by each code are slightly lower than those of test and FEM when the slenderness ratio is less than 50,while the results are too conservative when the slenderness ratio is more than 50.     

Full-Scale Test and Analysis of Mechanical Behavior of Concrete Filled Steel Tubular Column Node in Space Truss Structure

To investigate mechanical behavior and seismic behavior of concrete filled steel tubular column node (CFSTCN) in space truss structure, both full-scale test and Finite Element Method (FEM) were employed. The test load was 1.6 times of design load and by incremental step loading. Meanwhile, stress and deformation in CFSTCN were observed to monitor bearing capacity of the node. The results show that steel tubular works in elastic state and a small part of concrete beyond of compressive stress limits; steel tube and concrete adhesive well. The hysteretic energy dissipation capacity and failure mode under cyclic loading were revealed by nonlinear FEM. weakest position and ultimate bearing capacity of the node were obtained from FEM results. The method of combining full-scale test and FEM can well reveal the mechanical behavior and the seismic behavior of the node.     

Horizontal Ultimate Bearing Capacity Analysis of Multi-story Multi-span Steel Plate Shear Wails system

The effectiveness of equivalent strip model calculating the horizontal ultimate bearing capacity of multi-story steel plate shear walls(SPSW)by using the software SAP2000 to make Pushover analysis was demonstrated by comparing the simulated values with results from experimental studies performed by different researchers.The effect of different slenderness ratios on the ultimate bearing capacity of four-story single-span SPSW and four-story three-span dual steel shear walls system subjected to the inverse triangular load was obtained by the verified analytical model,which was compared with the performance of corresponding bare frames.The slenderness ratio of 250~300 is suggested for the design of SPSW.     

Overall Stability Design of Restrained H Section Steel Columns under Axial Load in Fire

The effects of the restraint stiffness ratio, the axial load ratio and the column slenderness on the buckling temperature and failure temperature of a restrained H section steel column under axial load in fire were studied with a calibrated finite element method (FEM) model. And the calculation methods of buckling temperature and failure temperature were proposed. The effect of the restraint stiffness ratio on the buckling temperature and failure temperatures could be expressed with an exponent curve while polynomial functions was appropriate for the effects of the axial load ratio and the column slenderness. The results of the proposed method were in good agreement with those by FEM method and on the safe side.     

Comparisons of Methods for In-Plane Bearing Capacity Calculation of Two-Hinged Parabolic Steel Arch Under Full-Span and Half-Span Loads

The internal force would vary largely with different load ratio for steel arches under combined full-span with half-span loads. However, most relevant formulas on in-plane stability capacity of steel arches were obtained by studying the stability under a single load. Thus, it lacks full considerations of the applicability of bearing capacity formulas under a combined full-span load with half-span load. To overcome this shortcoming, the two-hinged parabolic steel arch was used to compare the results of bearing capacity of arches with different load ratios, rise-span ratios and sections calculated by several methods, The method proposed in the current Chinese design specification of steel arch structure and the finite element method based on the perfect arch and the consistent imperfect arch were included. The results showed that the method in the specification for designing a steel arch would be conservative with a large ratio of the full-span load to the total loads while unsafe with a large ratio of the half-span load to the total loads.     

Influence Factors Study of Bearing Capacity of T Shaped RC Steel Reinforced Concrete Short-pier Shell Wall

In order to ensure that the T shaped steel reinforced concrete short-pier shear wall ductile shear failure occurs, the failure mechanism on the basis of experimental research, using ANSYS finite element analysis software to simulate the failure mode. In the process of analysis considered the influence factors of horizontal steel reinforcement ratio, concrete strength, axial compression ratio and the content of steel. The results show: the level of reinforced volume reinforcement ratio, concrete strength and the content of steel can obviously change the the bearing capacity and ductility of components.     

Discussion on Vertical Bearing Capacity of Rock-socketed Pile

Through analyzing the calculation of vertical bearing capacity of rock-socketed pile given in technical code for building pile foundations, some unreasonable issues in the code were found. At the same time, based on the contacting ways between the pile and the rock and the behaviors of force transfer acted step by step, the unreasonable issues have been proved and the issues to be improved were pointed out in this paper.     

圆钢管混凝土轴压长柱极限承载力的稳定系数法

为完善圆钢管混凝土轴压长柱极限承载力的计算理论,对比分析了中国国家标准GB 50936-2014和CECS 28：2012中轴压短柱极限承载力的N₀计算公式,并把GB 50936-2014中基于套箍系数的N₀计算公式改写成统一的形式,提出了基于正则长细比的轴压长柱的稳定系数计算式,并通过36个试件的对比,对计算式的精度和适用范围进行了分析。研究表明,现行国标GB 50936-2014中基于套箍系数的N₀计算公式更为精确,基于N₀计算公式和本文的稳定系数,可以计算得到更为精确的轴压长柱的极限承载力。     

FEA About Capacity of Resisting Explosion Inside of Short Concrete Column With Steel Tube Confined

With the development of offense and defense strategy in future war and the application of high tech weapon, the demand is much improved to the resistibility level of defense engineering. LS-DYNA3D software is adopted to simulate the situation causing by the explosion of the commonly short concrete column and Short Concrete Column with Steel tube confined. The comparison includes chamber causing by explosion and nodes' displacement. The results show that steel tube-confined concrete structure can confine the displacement of core concrete, improve the structure's capacity of resisting explosion effectively, and enhance structure's elasticity and firmness.     

Calculation of the Ultimate Bearing Capacity of Foundation under Triaxial Compressive Loading

It is of important significance to study the ultimate bearing capacity of foundation in three-dimensional stress. In this paper, a formula is established for ultimate bearing capacity of foundation taking three-dimensional stress into account. According to the numerical results, the ultimate bearing capacity of foundation with consideration of three-dimensional stress is improved, which is of important significance for engineering.     

Field Comparative Experimental Study on Bearing Capacity of Both Bored Pile with Branches and Plates and Column Bored Pile at the Same Site

Compared with column bored pile,the bored pile with branches and plates is a new type of piles with higher bearing capacity and lower settlement.Field comparative tests related to ultimate bearing capacity of both the bored piles with branches and plates and column bored piles at the same site in Huzhou city of province Zhejiang in China were studied through self-balanced method under static pressure.The results testify that,compared with column bored pile under the same geological conditions,the bored pile with branches and plates can obtain better economic benefit such as: increasing ultimate compressive bearing capacity and ultimate extraction bearing capacity used per cubic meter concrete over 75.3%and 118.9%respectively,while dropping consumption of reinforced concrete upwards of 41.9%and 44.1% respectively,reducing settlement and pile length under the same loading.The tests will present an objective reference to the new type of piles in both theoretic study and application to analogous engineering.     

Experimental Analysis on Behavior of Cold formed Steel Box Built up Section Columns under Axial Compression

17 specimens of cold formed steel box built up setion columns were tested under axial compression load. The section forms were divided into two categories: A and B. Load displacement curves and failure characteristics of specimens were obtained. The test results are compared with the caculated results according to “effective ratio of width to thickness” in code of “Technical code of cold formed thin wall steel structures” (GB 50018－2002), “effective section method” and “direct strength method” in AISI specification. The results show that: the failure characteristics of LC and MC series columns are overall flexural buckling, while SC series columns are local buckling and ends confined damage. The ultimate bearing capacity of B categories section columns is three times as great as that of A categories section columns, so it has the effect of “1+1＞2”. The results calculated according to “GB50018” and AISI specification are much conservative for LC series columns of A categories section, while in agreement with test results for MC and SC series columns. For B categories section columns, the calculated results are non conservative for LC and MC series columns, while conservative for SC series columns.     

Bearing Capacity of Reinforced Concrete Continuous Deep Beams with Web Openings Based on ANSYS Analysis

Based on the experiment on two-span continuous deep beams with web openings bearing concentrated load, setting a series of finite element simulation specimens and establishing finite element model by finite element analysis software ANSYS, the influences of the strength of concrete, the open hole size, the hole position, vertical reinforcement ratio and horizontal reinforcement ratio on bearing capacity and deflection of specimens were contrasted when imposed respectively.     

大昭寺景区旅游环境承载力评估指标体系研究

为建立一套适合西藏高原人文社会类型景区旅游环境承载力评价指标体系和评价模型,在现有的理论基础上,结合大昭寺景区的实际情况,构建了包含自然环境承载力、社会环境承载力、经济环境承载力3个承载力分量共27个评价指标的大昭寺景区旅游环境承载力评价指标体系。其次,采用AHP层次分析法构造判断矩阵、检验一致性,确定权重,建立景区旅游环境承载力综合评价模型,依据景区特点,建立大昭寺景区旅游环境承载力评价等级标准,对大昭寺景区各项指标进行测算,通过对上该景区旅游环境承载力的综合评价和分析,结果表明,大昭寺景区旅游环境承载力,基本属于适载阶段,最后提出了改善大昭寺景区旅游环境承载力的措施。