Search

The thermal deformation behaviors of the as-cast and wrought modified IN617 nickel-based heat-resistant alloys at different temperatures (1000–1180 °C) and strain rates (0.01–1 s−1) were studied. The constitutive equation was established to describe the relationship of the flow stress, temperature, and strain rate during thermal deformation. The effect of the thermal deformation conditions on the microstructure evolution of alloys was studied using electron backscatter diffraction. The results revealed that the thermal deformation activation energy of the as-cast alloy was greater than that of the wrought alloy. The dynamic recrystallization (DRX) process is slow at intermediate strain rate (0.1 s−1) due to the comprehensive influence of various factors, such as the critical strain of DRX nucleation and stored energy. The DRX volume fraction increases with the improvement of deformation temperature. The varied dynamic softening mechanisms induce the different thermal deformation behaviors of as-cast and wrought alloys. The dynamic recovery, discontinuous dynamic recrystallization (DDRX) and nucleation at slip zone caused by strain incompatibility in grains were observed during thermal deformation of as-cast alloys. In the process of thermal deformation of wrought alloys, DDRX was the primary dynamic crystallization mechanism. The continuous dynamic recrystallization was an auxiliary nucleation mechanism.

This paper presents a parametric study on the lateral-torsional coupling behaviours of soil-multistorey bidirectional eccentric structure interaction system from elastic stage to nonlinear inelastic stage. A simplified bidirectional eccentric multistorey dual lateral load-resisting model for the superstructure is proposed to conduct this parametric study. Incorporating the inter-storey restoring force model of the superstructure, the dynamic motion equations and the dynamic stiffness matrix of the soil-multistorey bidirectional eccentric structure interaction system in different loading stages are derived. Based on these, parametric analyses of frequencies and seismic responses for the soil-three storey structure interaction systems from elastic stage to nonlinear inelastic stage are evaluated. Effects of the uncoupled torsion to lateral frequency ratios (Ω) of the corresponding fixed base system, the stiffness eccentricities and different soil types on the frequencies and seismic responses are investigated. Results show that the soil can significantly reduce the lateral-torsional coupling effect and the structural seismic response of the soil-bidirectional eccentric structure interaction system; a smaller Ω value and larger values of the eccentricities lead to a larger reduction in the lateral-torsional coupling effect of the first order mode in nonlinear inelastic stage; the effects of different foundation conditions on the structural seismic responses are weakened by the development of structural inelastic; after considering the soil-structure interaction, the influences of Ω and eccentricities on the structural seismic responses are changed. A softer soil-structure interaction system has a more weaken lateral-torsional coupling effect, and its vibration modes in nonlinear inelastic stage are changed compared with the system situated on other soils.

Spare inventory optimization is one of the important problems for a maintenance facility to repair equipment in a high efficiency and low cost manner. In this paper, a model is developed to solve the problem of spare parts decision for complex system maintenance with mixed multi-echelon spare inventory. Spare parts are categorized into three types in terms of number of inventory echelon. Spare support availability and costs are analyzed respectively for each type.

Structure would be in different extent of translational-torsional coupling due to the inconsistent of mass center and stiffness center which caused by the irregularity of floor mass and stiffness distribution. At present, the research on seismic response of the eccentric structure was not perfect, especially the translational-torsional coupling response considering soil-structure interaction. This paper briefly reviewed the research status on the lateral-torsional coupling considering soil structure interaction effect and point out several problems existing currently in the field in order to make necessary preparations for analyzing seismic response of eccentric structure more in-depth.

A shaking table test of large-scale pile-soil-complex structure interaction is accomplished on the transport hub of Tianjin station, and some reliable testing data of soil-structure dynamic interaction laws are acquired. ANSYS is used to simulate the process of the test, including establishment of 3D FEM model, selections of material parameters and constitutive, treatment of boundary conditions. Comparative analysis is performed between simulation data and testing data. The results show that: the simulative results agree well with the experimental ones under small earthquake, but the deviation increases when it suffers medium earthquake. The rationality of the numerical simulation and test are verified by each other, and the causes of the deviation under medium earthquake are analyzed.

An analytical approach based on branch mode method is formulated in this paper to study the dynamic response of eccentric structure considering soil-structure interaction The superstructure branch and foundation soil branch are coupled through mode aggregation procedure. The computational scale of system equations decreases to an acceptable level. Sample analysis indicate that the seismic response of eccentric structure increases first and then decreases with the decreasing of stiffness of soil-foundation system, which is affected by the inertia effect of foundation branch. For the soft soil case, the influence of SSI effect is more intensive that the trends of transfer function curves are fundamentally changed comparing to the results of other foundation conditions.

According to hot research of subsidence time function at home and abroad in recent years that there are commonness of less parameters and difficult to extended reflecting surface subsidence characteristics in the dynamic process, the surface subsidence dynamic coordinates time function were proposed based on the probability integration principle, established the calculation methods of surface dynamic process, anal sized the applicability and limitations of the dynamic time function and verified some examples. The results show that the function is more accurate than the Knothe time function in analyzing the actual regularity of surface subsidence caused by underground mining, reflecting the dynamic characteristics of surface movement in real time, interoperating mining phenomenon, it is more accurate to predict dynamic ground displacement and deformation which has a certain significance value in mining design and subsidence disaster management.

Based on the soil-structure interaction theory and finite element method, this paper analysis the seismic response of pile-soil interaction system in super high-rise building. This paper established a structure- pile-soil finite element mole of a super high-rise building in Tianjin area and analysis the dynamic response of superstructure and the internal force and displacement of the pile considering the influence of pile’s slenderness ratio. The results show that, the displacement and acceleration of the top of interaction model are increased compared with the fixed base model. Under seismic excitation, the peak displacement and the peak acceleration of pile top are larger than the pile bottom. As the pile’s slenderness ratio is larger, the inter force and displacement seismic response of the pile is larger and the variation of peak is bigger along the pile.

The simplified calculating model for fiber plasterboards filled with concrete core columns with different spacings was established. The method for calculating the moment-curvature relationship of concrete core column and the force-displacement skeleton curves of shear element was then proposed. The test data of fiber plasterboards filled with concrete core columns with different spacings were analyzed based on this model. The calculated curves agreed well with the experimental ones, which proves that this model has the advantages of clear mechanical conception，simple calculation and relatively good accuracy，and is convenient for calculating integral structure.

In order to understand the seismic performance of the large complex structure with multi-storey basement, the structure-pile-soil finite element model of a typical cross sections of one transfer station in a transportation junction were established by using the ANSYS software. The time history analysis was adopted, and the seismic responds of the whole system under the seismic load was analyzed, and some rules were attained. Comparing the result of the seismic responds with the rigid foundation model which the soil around the underground structure simulated by spring element, and some salutary conclusions are attained.

The interfacial mechanical characteristics in anchorage zone of grouted bolts influence the ultimate capacity of bolts directly; a push-out test was carried out at the lab to study the interfacial mechanical characteristics in the case of bond failure happening at the grout-rock interface, leaned from some scholars to test methods for analysis of concrete microstructure instead of rocks. The commercial finite element software ANSYS method was adapted to analyze the dilatancy effect on the concrete during the grout was pushed out. Using conversion between compressive strength and tensile strength of concrete cube, the tensile strength can be calculated, as the basis for destruction of the concrete matrix.

In this paper, the vortex-excited resonance analysis are performed for main stay bar of a new type large-span bridge and the structural maximum displacement response in resonance state is calculated by programming , to be obtained the maximum displacement response and its occurring position of main stay bar in the vortex-stimulated resonance state caused by wind. The bottom of the main stay bar is fixed connection and the top is hinged. Because the bottom of the main tower fixed with better conditions, the maximum displacement should occur the place where are up middle of the main stay bar under the action of external loads. The analytical results show that the real compute results are better consistency with this judge. The results of this paper provide the base for the wind-resistant design of large-span bridge and can be to references for the coming bridge

The simplified calculating model for concrete-filled gypsum wall panels was established. The method for calculating the moment-curvature relationship of concrete core and the force-displacement skeleton curves of shear element was then proposed. The test data of concrete-filled gypsum wall panels were analyzed based on this model. The calculated curves agreed well with the experimental ones, which proves that this model has the advantages of clear mechanical conception，simple calculation and relatively good accuracy，and is convenient for calculating integral structure.

How to establish the bond-slip constitutive relation model of concrete and gypsum board will be of great academic significance. Through the pull-out experiment of CFFP, the load-slip curves is obtained. The characteristics and research situation of bond-slip performance at the inter face of concrete and other materials are introduced, and the bond-slip constitutive relation models are summarized at the same time. By using the fitting operation, the proposed constitutive relation is put forward , which is feasible and can be applied to further research on CFFP.

Based on the test results of composed-wall-specimens made of fiber-reinforced gypsum panel and concrete core columns, ADINA finite element models of composite walls were established in this paper. Parametric studies were conducted on this basis, which would investigate the effects of fiber-reinforced gypsum panel, concrete core rate, height-width ratio and concrete strength on the load-carrying capacity of the composite walls.

The study on bond-slip performance at the interface of concrete frames-fiber plasterboard (CFFP) is very significant to perfect the theory of CFFP and the FEM analytical models. The pull-out experiment on eight CFFP from three series does research on the effect of concrete strength and the interface length on the interfacial bond strength of fiber plasterboard and core column concrete. The experiment of CFFP is well-designed to obtain the curve of bond-slip constitutive relationship.

The characteristics and research situation of bond-slip performance at the inter face of concrete and other materials are introduced, and the bond-slip constitutive relation models are summarized at the same time. Through the load-slip curves obtained from the pull-out experiment of CFFP, the proposed bond-slip constitutive relation models are presenting, including the simple one. With the numerical simulation analysis of CFFP is carried out by the use of the proposed constitutive relation, while the numerical simulation results are in good agreement with the experimental results conducted before, which is feasible and can be applied to further research on CFFP.

The new way of using mechanical joint element (MJE) to cross the interface of new and old concrete to reinforce the combination is put forward. The splitting strength tests of young and old concrete were carried out to investigate the effects on splitting strength of MJE and different materials used to embed the MJE. The working mechanism of the MJE in split test is discussed emphatically. The shear tests of young and old concrete were carried out too. The effects on shear strength of MJE and interface agent are discussed. The mechanism of MJE in shear test is analyzed synchronously.

Glass fiber reinforced gypsum (GFRG) walls, known as a green product that helps to save energy and protect the environment, are promising new building materials developed in Australia in the early 1990s. Driven by the wide-spread interest from the construction industry and the research community, substantial research has been carried out in Australia and a few Asian countries such as China, Malaysia and India to investigate its performance, including the structural behavior for building construction. This paper investigates the shear strength of GFRG walls fully or partially filled with concrete in the hollow cores. Eight full scale GFRG walls were tested under cyclic loadings. The shear performance of the tested walls, including the shear failure mode, hysteresis responses, the ultimate shear strength and the axial load effect, were studied in the paper. With the aid of nonlinear finite element analyses, a design procedure for the shear strength of the concrete filled GFRG walls is developed.