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.     

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.     

Study on the Terzaghi Ultimate Bearing Capacity of Foundation Based on the Unified Strength Theory

The ultimate bearing capacity of foundation based on Mohr-Coulomb strength criterion did not analyze effect of intermediate principal stress on yield and failure of soil so that the disparity between results obtained using Mohr-Coulomb strength criterion and those from experimental data are produced .In the paper , The ultimate bearing capacity of foundation based on unified strength theory is established and a unified solutions are obtained. The corresponding solutions of different materials can be got from it .The unified solution can not only be used to fit the properties of the materials with different tension-pressure strength but also those with equal tension-pressure strength, Results show that ones make full use of the properties of the materials so as to reduce supports,which is of important significance for engineering.     

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.     

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.     

Lateral Bearing Capacity and Simplified Equations of Dry Stack In filled Reinforcement Concrete Frame Structure

The mechanism and lateral bearing capacity of reinforcement concrete (RC) frame with dry stack in filled panel (DSIP) were investigated using quasi static experiments and finite element models. According to the parallel model and equivalent strut model, the lateral bearing capacity of RC frame and DSIP were researched separately. Results show that: 1) The plain stress element and interface element are applicable in finite element (FE) model analysis. According to the FE model, the failure of RC frame with DSIP is caused by the damage of frame; 2) Lateral bearing capacity of DSIP is mainly from the friction between bricks in the panel, which can be divided into 3 stages: constant stage, increasing stage and ultimate stage; 3) Equations for lateral bearing capacity of DSIP were proposed and verified by FE model results.     

Ultimate Bearing Capacity of Concrete Two-way Composite Slabs with Precast Concrete Ribbed Panels

New types of precast concrete ribbed panels are developed in order to adapt to the complex loading conditions and different floor spans. Based on the yield line theory, equations for the ultimate bearing capacity and yield patterns of two-way composite slabs of different edge conditions and under uniformly distributed loading are developed, and the simplified formulas for the ultimate moment per unit width are proposed. The plastic limit analyses of two examples on the simple support and the fixed support are conducted, and the calculation results show good agreement with the experimental data.     

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.     

Bearing Capacity of Bar-Reinforced Concrete-Filled Square Steel Tubular Short Columns After Fire

Based on the determined stress-strain relationship of steel and concrete after fire, a temperature field and mechanical model of bar-reinforced concrete-filled square steel tubular columns after fire was set up with using ABAQUS, and the model has been validated by testing results. Then this paper analyzed the side of section, bar ratio, fire duration time, steel ratio and material strength parameters on the bearing capacity of bar-reinforced concrete-filled square steel tubular columns after fire. It is found that fire duration time and side of section is the dominant factor. Lastly this paper puts forward a theoretical formula of bearing capacity of bar-reinforced concrete-filled square steel tubular columns after fire, for the post-disaster restoration and provides references for the reinforcement.     

Nonlinear Analysis on the Ultimate Strength of the Slender Frame Columns for Chongqing Grand Theatre

To investigate the influence of accidental eccentricity, embedded-in foundation condition and other factors on the ultimate strength of the RC slender frame column for Chongqing Grand Theatre, a nonlinear analysis of the local frame composed of peripheral     

Research on Index of Reliability for Bearing Capacity of Rock - Socketed Single Pile in Chongqing

Based on the data from in-situ 102 rock-socketed test piles in Chongqing in recent 10 years and utilizing the limit state equation of the dimensionless random variables,the reliability analysis of the bearing capacity of rock-socketed single pile is made and the scope of the target reliability of rock-socketed piles in Chongqing is calculated with both JC method and Monte-Carlo method respectively.Furthermore,the target index of reliability is suggested.Finally,the concept of reliability coefficient(to replace the load partial factor and the resistance partial factor) is given and the bearing capacity of the single pile is determined by utilizing optimization method.Besides,the practical limit state design equation using reliability coefficient is put forward for its advantage of incarnating the simple and practical principle and being easy mastered and understood by the designers.     

Structural Influencing Coefficient of Moment-Resisting Steel Frames Based on Equal Collapse Rule

In order to realize the performance target of “no collapse under rare earthquake” based on the seismic design according to structural influencing coefficient, three moment-resisting steel frames have been designed with similar probability of collapse in accordance with Chinese Seismic Code. The structural influencing coefficient of steel frames were determined through the incremental dynamic analysis method, and within equal collapse design rule. This paper proposed a method to define structural influencing coefficient can provide reference for determining the design seismic force of steel frame reasonably.     

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.     

Factors of Bearing Capacity for Rock Foundation Based on the Nonlinear Failure Criterion

Bearing capacity of foundation is conventionally calculated based on the linear Mohr–Coulomb failure criterion. However, a amount of experimental data shows that the strength envelops of almost all types of rocks are nonlinear over the wide range of normal stresses. The strength envelope of rock masses is considered to follow a modified Hoek Brown nonlinear failure criterion. Therefore, according to the upper bound approach, based on Hoek Brown nonlinear failure criterion and a multi tangential technique method, the relevant programs were developed by means of the software Matlab and the sequential quadratic programming optimization theory. And the calculation and the analysis of affecting factors bearing capacity for rock foundation were employed. It is found that the major factors affecting bearing capacity of rock foundation are GSI and mi, but the weight of foundation ,overload and the disturbance coefficient of excavation D have a considerable influence on bearing capacity of rock foundation when the value of GSI is small . Compared with the generalized tangential and the finite element or finite difference numerical techniques, the single tangential technique method would bring relatively great risk, because the calculation results are larger than those of the actual bearing capacity of foundation.     

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.     

Stratification and Bearing Capacity Prediction Method Based on BP Neural Network for Foundation in Huaibei Plain

According to the features of stratification and obvious inhomogeneity in geological soil in Huaibei plain, BP neural network prediction method for stratification and bearing capacity calculation of multiple cross-bedded foundation was proposed. By comparing the results of drill sampling, static cone penetration tests and screw plate tests, plate loading tests, penetration resistance ps value was found as an evaluation index for stratification and bearing capacity prediction of cross-bedded foundation. Moreover, gradient descent algorithm and conjugate gradient algorithm BP neural network models were obtained, and the calculation results of the two algorithms were comparatively analyzed. The results show that penetration resistance value can be taken as an evaluation index for stratification and bearing capacity prediction of cross-bedded foundation in Huaibei plain. Gradient descent algorithm and conjugate gradient algorithm BP neural network models have good results for soil identification and bearing capacity determination, which can meet the accuracy requirements of actual engineering. However, the computational efficiency of gradient descent algorithm is significantly lower than that of conjugate gradient algorithm.     

Determination Method on Diameter of Cables in Mega Steel Frame and Composite Brace Structure

How to determine the diameter of cables is one of key problems in mega steel frame and pre-stressed composite brace structure. Firstly, through analysis of work mechanism of composite brace under horizontal load, the deciding factor of diameter value was found, and furthermore its rule was proposed. Finally, the determination equations were acquired through theoretic deduction and were proved with numerical example. The results indicate that the unbalance in composite brace resulted from antisymmetric load can be eliminated only by antisymmetric way. Thus the diameter value is decided only by antisymmetric horizontal load, and its rule is to keep the balance of composite brace under horizontal load. The influencing factor iterative leveling method can consider the influence from upper and lower floor, and is relatively accurate and feasible.