Advanced Materials Research Vols. 243-249

Abstract: Little progress has been made in experimental studying on high-temperature mechanical properties of concrete under multiaxial compression. Triaxial proportional compressive tests of ordinary concrete after suffering to high temperature (200°C ~600°C) were carried out, the designed stress ratios are 0.1:0.25:1, 0.1:0.5:1, 0.1:0.75:1 and 0.1:1:1. The failure models of concrete specimens after suffering high temperature were observed. The biaxial compressive strength and deformation characteristics of which were measured. The influences of temperature and stress ratio were analyzed. On the basis of the analysis, the relationship between compressive strength and temperature as well as stress ratio was established in octahedral stress space.

Abstract: A bolt-ball is a commonly joint form in latticed shells. It’s a typical semi-rigid joint, which can bear certain amount of bending moment. The performance of triangle mesh single-layer cylinder shells with bolt-ball joints in different support conditions has been analyzed detailed using the finite element (FE) software ANSYS based on several different parameters including bending stiffness, torsional stiffness, shell span, ratio of rise to span, ratio of length to width and load distribution in this paper, and key influence parameters to the load carrying capacity of cylinder shells with semi-rigid joints in different support conditions are obtained. Finally, based on the results obtained by FE calculation, a new formula is proposed for getting ultimate load of single cylinder shells with semi-rigid joints in four sides support, some references are provided for shell design.

Abstract: To understand mechanical characteristics of frame joints of steel truss SRC beam, the accuracy of the proposed method is proved by the comparison between FEA result and test result, considering different steel ratios, cross flank rods and axial loads as well as plastic model of concrete damage. The result indicates that cross section and steel can delay joint damage and improve the bearing capacity, and that axial load can improve joints shear capacity to some extent but joints ductility is decreased, and that constraint of steel to concrete improves brittleness character caused by bad ductility of concrete.

Abstract: In order to research the seismic performance, eight joints with steel truss SRC beam and RC column under low-cyclic reversed load was conducted, and the failure process and patterns were observed. The test indicates that two types of failure patterns can be seen from specimens, including shear failure and bending failure. By the analysis of the failure characteristics and mechanism of joints, the load-displacement hysteretic curves and load-strain hysteretic curves are presented, and the formula for calculating ultimate shear capacity of joints is gained finally. The calculating results are in good agreement with those of tests.

Abstract: In the present paper, a new creep-fatigue crack growth model of J-integral criterion is proposed. The model is built based on the dislocation-free zone (DFZ) theory and cohesive zone model. The process of crack growth is viewed as the intermittent quasi-cleavage fracture of the DFZ. The microscopic void caused by creep will grow and join the dominant crack under creep-fatigue interaction. In this process, material’s plastic deformation induces the change of the dislocation’s density. The redistribution of dislocation will change the value of J-integral within the cohesive zone. When the value of J-integral attains the critical value J_c, crack will grow by the original width of DFZ. Based on it, a simple relation is employed to evaluate crack growth rate under creep-fatigue interaction. The calculated crack growth rate curve exhibits three different regimes, which is in agreement with the general crack propagation pattern under creep-fatigue interaction. The model gives a reasonable explanation for crack growth under creep-fatigue interaction. The calculated value is close to the value obtained by experiment.

Abstract: In this paper, the influence of correlation of variables on structural reliability is discussed. Using importance, condition and duality sampling techniques of Monte Carlo method, accepted accuracy can be obtained. For the limit state function, the correlation of random variables will influence structural reliability, and the influence can be described. For the case of positive correlation, reliability will increase as the the correlation coefficient raise. For the case of negative correlation, reliability will drop as the correlation coefficient raise. The level of influence depends on the slope of limit state equation in standardized coordinate. When k=1, the influence attains maximum intensity for both cases.

Abstract: Enhancing column flexural capacity is the key measure in seismic capacity design to achieve strong column-weak beam failure mode and determinate the probabilistic relation between column moment magnification factor (CMMF). In the paper the effects of column moment magnification factor on seismic performance of reinforced concrete (RC) frames are evaluated to limit the occurrence probability of column-hinging failure modes within an acceptable tolerance. Monte Carlo simulation methodology is used to calculate the probability of drift demand exceeding drift capacity of two typical frame structures with consideration of major uncertainties. And fragility curves are constructed to obtain the relationship between CMMF and probability of structural damages and assess the seismic vulnerability of RC frame structures. Results show that the seismic performance of RC frame structures can be significantly enhanced by improving CMMF. The CMMF is required to be equal to or greater than 2.0 to achieve acceptable probability of exceedance of column-hinging failure mode.

Abstract: Laminated glass has been increasing widely used in high rise buildings as a kind of safety glass in recent years. So we should analyze its material property. In this paper, we use flexural experiments and ANSYS program to analyze the main factors that affect the flexural capacity of the laminated glass. The test results show that the flexural capacity is closely related to film. And the ANSYS program had got good agreement with the experimental results. Comparison of experimental results with calculated ones indicates that the current design code will lead to conservative results and the equivalent thickness of laminated glasses provided in the code should be further discussed.

Abstract: Cable sliding in membrane pockets or on membrane surfaces has not yet been considered in analysis of cable-membrane structure software. In this study, a new sliding cable element has been created, using the non-linear finite method and a model of line-elastic and non-linear sliding stiffness. First, this paper outlines existing computational methods for creating sliding cables and questions the accuracy of these current numerical models. Second, it determines the sliding stiffness of sliding cables by examining the relationship between the original length and the end tension of space two-node linear cable elements. Third, the solution arithmetic for cables sliding in membrane pockets or on membrane surfaces is proposed with consideration of correctional linear sliding stiffness. Finally, the method developed herein is validated by one example.

Abstract: Double-limb lipped channel section steel member is formed by connecting two single limb members with bolts in order to improve the buckling performance. In order to research the buckling form and ultimate bearing capacity of members with different slenderness ratios under axial load, nonlinear analysis of buckling performance is done to this kind of section using the finite element analysis software ANSYS. The influence on bearing capacity caused by height-breadth ratio of section, height-thickness ratio of web and breadth-thickness ratio of flange is analyzed. The results show that: (1) for larger slenderness ratio, complete buckling occurs to the column mainly and the slenderness ratio has larger influence on buckling bearing capacity, while for smaller slenderness ratio, local distortional buckling occurs more; (2) in a certain range, the increase of height-breadth ratio could raise the ultimate bearing capacity of member, but excessive height-breadth ratio would make the ultimate bearing capacity decrease, (3) the increase of both height-thickness ratio and breadth-thickness ratio would decrease the ultimate bearing capacity.