Applied Mechanics and Materials Vols. 351-352

Abstract: In this study, to evaluate the bending performance and the shear performance of Aramid Fiber Plate Strip with enhanced attachment, 8 specimens were made for experiment. Most flexural failure specimens showed AFPS rip-off failure or separation failure. In the shear failure specimens, the specimens showed a brittle failure in which the concrete compression edge was broken. Compared with the control beam, the maximum ultimate strength increased by 164~193% for the flexural failure specimen, and by 218~259% for the shear failure specimen. The ductility, however, decreased steeply in the shear-failure specimen as the amount of reinforcement grew.

Abstract: An experimental investigation on the dynamic characteristics of unbounded prestressed concrete simply support beams is presented. A total of 5 unbounded prestressed concrete simply support beams were constructed and tested. The influence of prestressing on natural vibration frequency of concrete beams is studied by applying prestress gradually. A model of variable stiffness is proposed to calculate the natural vibration frequency of unbounded prestressed concrete beams. The finite element program Sap2000 is used to calculate the frequency of unbounded prestressed concrete beams. The results show that the calculating results agree well with experimental ones.

Abstract: The paper illustrated design process and announcements of the reconstruction through a project example.The structure had been made an integral analysis by analysis software MIDAS/GEN which can separately consider different material damping ratio. The results show that Structure would be more likely to generate the translational mode based on concrete vibration in the earthquake.This paper introduced the application of the design concept of green building in this project.

Abstract: In order to study the relationship between prestress and natural frequencies and the factors of influence natural frequence change, a dynamic test on three simply supported externally prestressed concrete beams of different prestressed level was carried out. The results showed that the eccentricity and arrangement of externally prestressed tendons and the constraints have more influence on natural frequencies than prestress itself. The prestressed effect comes from combined action of the several factors, and the natural frequencies of beams were found to agree well with the prestress. It appears that higher order frequencies have greater increment usually.

Abstract: A cohesive model (CM) was introduced in this paper. The constitutive response of cohesive behavior depends on a traction-separation description characterized by the initial stiffness, damage initiation threshold, and damage evolution properties.Through the aseismic analysis of a gravity dam, the displacement, stress and anti-sliding safety factor were discussed in the paper, the results were also compared between elastic model (EM) and plastic model (PM). The results shown that the displacement amplitude computed by PM and CM was nearly twice larger than that by EM, and the area of stress concentration became not so obvious. The cohesive model could efficiently simulate the discontinuous structure and the responses of seismic computed by PM and CM were more correspond to actual situation.

Abstract: Calculation of effective length of columns is key of stability checking in design, therefore some formulas and tables are given in Code for Design of Steel Structures (GB 50017-2010), which show some application Limitations. These formulas and tables are made based on assumptions for regular frames. For some special cases, such as existence of the large difference of the column axial force or column length among the framework columns, these formulas and tables are no longer applicable. The practical calculation charts are derived by authors by using the displacement method with the second-order theory, which can be used to quickly determine column effective length and show intuitive trends of the lengths.

Abstract: Suspend-dome structure form which colligates advantages of cable dome and reticulated shell is a new type spatial hybrid structure system. This article introduced the configuration and principle of suspend-dome structure system, and researched the structural behavior influence by altering the joint stiffness, vector height of the suspend-dome and the loop cable pretension. The results show that suspend-dome structure should make comprehensive consideration on interaction between vector height, prestress application and other factors, and relevant optimizing design method can be adopted in the design.

Abstract: This paper presents a model test research on long-term deflection of prestressed steel-concrete composite beams caused by creep and shrinkage effects of concrete. The model is designed based on a 20.8m length segment of a service composite beam bridge in Guangzhou. Geometric scale between the model and prototype is 1:8. Long-term deflection of the test model was obtained through 300 days of uninterrupted test. In addition, using the CEB-FIP (1990) criterion, effective modulus of concrete was calculated considering the effect of the concrete creep and shrinkage. Uniform the effective modulus of concrete to the modulus of steel, the value of structures time varying stiffness was calculated with single material theory and the relationship between stiffness and deflection by introducing stiffness adjustment coefficients was established, then the value of deflection changing with time was calculated.

Abstract: The objective of this paper is to introduce a simple experimental apparatus based on the applied forces for quantitative assessment on hot tearing behavior in aluminum alloys. According to the experimental procedure, molten metal is cast in the rod-shaped mold cavity. One side of the casting specimen is hooked by a steel bolt which restrains its free contraction and transfers the tensile forces during solidification. A steel threaded rod connected to a load cell which records the real-time measurement of the tensile forces during every experiment. Thermal history is monitored by K-type thermocouple. The data of the temperature and tensile forces are acquired by a data acquisition system. Test of the experimental apparatus is conducted with A356 and Al-5wt%Cu alloy to investigate the accuracy of the experimental apparatus and modify its operating parameter. The tensile forces curves and the temperature curves of the specimens are obtained by experiment. This data provide useful information about hot tearing formation and solidification characteristics, from which their quantitative relations are derived. In this manner, the hot tearing behavior in aluminum alloys can be studied by this experimental apparatus based on the applied forces.

Abstract: Electrochemical behavior of 304L and S32304 stainless steel in different temperature and concentration phosphoric acid solution by means of polarization curve and electrochemical impedance spectroscopy. The results showed that with the increase of the phosphoric acid solution temperature, the corrosion voltage and the corrosion current of the stainless steel increase and the polarization resistance and solution resistance decrease. The corrosion-resistant properties of S32304 stainless steel are superior to that of 304L stainless steel.