Applied Mechanics and Materials Vols. 166-169

Abstract: A tri-layered cracked beam under opening loading is developed for the interfacial fracture toughness measurement. Determination of the mode I strain energy release rate along the second and third layers of the tri-layered beam is carried out analytically. The analytical prediction of the strain energy release rate is validated with the finite element results. The influences of the layer thickness and Young’s modulus on the strain energy release rate are examined through a parametric study.

Abstract: A lot of problems is conversed to their corresponding research area and studied. In this paper, electrical experiment method is presented for solving a single-degree-of-freedom (SDOF) dynamic system subjected sinusoidal loading. The equivalent electrical circuit corresponding to the SDOF dynamic system is designed and practical electrical circuit is completed. Research results shows that the electrical circuit analogy method (ECAM) is an effective and practical method on solving structural dynamic problems. The electrical experiment results agree well with the numerical simulation results.

Abstract: Lamb wave scattering at a rectangular hole are investigated by using modal decomposition method. Take advantage of the biorthogonality relation, the scattering matrix is derived in an explicit form. The efficacy of the method is illustrated by numerical examples. The results are compared with those gotten from numerical models and the calculation accuracy is analyzed.

Abstract: The use of finite element analysis has been widely used as a means to analyze individual elements and the effects of concrete strength under loading. This paper is a study of prestressed concrete beams made of strain hardening material called UHP-SHCC (Ultra High Performance Strain Hardening Cementitious Composite) using finite element analysis to understand their response. A finite element model is studied and compared to experimental data. The basic parameters included second order effect of prestressed beam, and prestressing tendon depths have been considered in the analysis. The present study indicated the following conclusions: the number of deviators significantly influences the ultimate capacity and the strains values of UHP-SHCC beams, the change of external prestressing tendon depth has a significant effect on the cracking load, failure load, deflection values, and ultimate stress in the tendon in case of using UHP-SHCC beams but keep the final mode of failure without change.

Abstract: Based on the plane-section assumption, the formulas of yield moment and ultimate moment are derived for calculating high-rise RC shear wall. High-strength steels are used as transverse and longitudinal steels in boundary concealed columns of the shear wall. The practical application is performed by using the formulas derived for calculating horizontal bearing capacities of four specimens, in which one specimen used ordinary-strength steel and the others used high-strength steel. Meanwhile, the numerical simulation is carried out on the four specimens by finite element method, and the results show that the horizontal bearing capacity of the shear wall increases obviously for specimens using high-strength steel in boundary concealed column, and the simulation results of finite element method are in good agreement with formula results.

Abstract: An experimental investigation on the dynamic characteristics of unbounded prestressed concrete simply support beams is presented in this study. A total of 3 unbounded prestressed concrete simply support beams were constructed and tested. The main variables considered in the test study were the prestress level, the position of prestressed steel and concrete damage. The test results shows that the natural frequencies and model shape of prestressed concrete beams change with the prestress level and the position of prestressed steel, and that the existence or not of concrete crack have certain effects on the dynamic characteristics of prestressed concrete beams.

Abstract: The superstructure and its foundation of a super tall building mega-frame structure are simplified equivalently and continuously to a stiffened-thin-wall tube on semi-infinite elastic subgrade. And the influences of static response on super tall building mega-frame structure caused by changes of frame rigidity are computed and analyzed with the three-dimensional model by semi-analytical approach based on ODE(Ordinary Differential Equation) Solver, considering the interactions of subgrade, foundation and superstructure. Then some valuable conclusions are obtained through analyzing the reasonable results of the numerical example.

Abstract: Initial imperfections on beam string structure (BSS) include geometric imperfections and residual stresses, which negatively influence the mechanical properties of BSS. This paper analyzed the mechanical influences of initial imperfections on BSS by FEA, pointed out that initial imperfections do not remarkably influence the properties of BSS in stage of prestressing, but geometric imperfections obviously influence the displacement out of plane in stage of use, which should be controlled to improve the safety of BSS by installing enough lateral supports at the upper chords of BSS in construction.

Abstract: Concrete filled steel tubular (CFST) column-beam joint with the column tube discontinuous in joint zone is a new type of joint. Firstly, the results of the cyclic loading experiments on this joint were introduced briefly. Then numerical simulation of the experiment process was carried out by OPENSEES, and the load-displacement curves, strength degradation, stiffness degradation of the specimens were studied. The analysis results exhibit good agreement with the experimental ones. OPENSEES can simulate two types of failure, including joint failure and beam failure. Based on specimen S3, parametric analysis were conducted to research the strength degradation and stiffness degradation in models with different reinforcement ratios and reinforcement diameters. The results indicate that models with higher reinforcement ratio of the beams will result in joint failure under cyclic reverse loading, and their load-displacement curves are pinched and ultimate bearing capacity would not increase while strength degradation and stiffness degradation would appear obviously.

Abstract: The test results of nine stub-column tests performed on partially encased composite (PEC) columns made with welded H-section steel are described and presented. The H-section steel is stiffened with transverse link and concrete is poured between the flanges of the steel section. The axial comprehensive study has been conducted on all specimens to investigate the ultimate axial capacity of PEC columns. The failure of all columns is due to local buckling of the flanges along with concrete crushing. Closer link spacing improves the ductility of the columns; however, the measurements show that in general yielding do not occur before the peak load in the links. The additional longitudinal bars have no a remarkable effect to the strength of the composite columns. Finally, an equation is proposed to predict the ultimate axial capacity of the partially encased composite column.