Advanced Materials Research Vols. 163-167

Abstract: In accordance with the philosophy of performance based seismic design (PBSD), the fully operational performance level (or service performance level) for frequently occurring earthquakes and the criteria for determining its allowable drift indices is discussed in this paper. To determine the allowable drift limits of the service performance level for frequently occurring earthquake, it is important that not only the degree of damage of nonstructural members but also the degree of cracking in structural components should be controlled. Based on an analysis of test results and calculation results, a series of allowable drift index limits that conform to the fully operational performance level of RC structures are presented.

Abstract: In order to study the stress distribution in hinge joints of different depth and the effects of hinged plate by hinge joints depth, 5 group ANSYS finite element models of concrete simply supported hinged plates were built, hinge joints stress of models have been compared under the center load and side load, analysis has been made on the hinge joints of maximal stress. The analysis results indicated that with the increase of the depth of hinge joints, the transverse tensile stress, vertical shear stress and longitudinal tension stress were all showed regular distributions, and with the increase of the depth of hinge joints from 10cm to 26cm, the maximum reduction value of transverse tensile stress in hinge joints was 3.25MPa, the reduction range was 51.9%; the maximum reduction value of vertical shear stress was 1.06MPa, the reduction range was 77.9%; longitudinal compressive stress decreased gradually, and longitudinal tensile stress increased; the maximum reduction value of hinged plates deflection difference was 0.16mm, the reduction range was 36.4%; the transverse tensile stress of hinged plates’ bottom increased. Therefore, increasing the depth of hinge joints was the most effective way to increase the transverse stiffness of slab girder and to prevent hinge joints damage. At the same time, the tensile reinforcements setting in transverse and longitudinal at the bottom of hinge joints and the tensile reinforcements setting in transverse at the bottom of slab girder should be strengthened.

Abstract: To study the role of vertical shear stress on the ultimate bearing capacity of hinge plates under fatigue loading, and different configurations of hinge joints on ultimate bearing capacity of hinged plates, three groups of hinged plate experiments were studied. Two groups of hinge plates with shallow hinge joint configurations were tested with static loading and fatigue loading respective, a group of hinge plates with deep hinge joint configurations were tested with fatigue loading directly. The ultimate bearing capacity analysis of hinge plates was carried out through mid-span deflection differences of hinged plates on both sides of hinge joints and transverse strains on top and bottom of hinge joints. Shown from the experimental results, for the hinge plates with shallow hinge joints, the ultimate bearing capacity under static load was 342.9kN, and under fatigue load was 340kN, but the ultimate bearing capacity under fatigue load of hinge plate with deep hinge joints was 610kN. Therefore, the vertical shear stress is not the main factor which cause the hinge joints destruction of hinge plates; hinge joints configurations, especially the depth of the hinge joints have great impact of ultimate bearing capacity of hinge plates; in the strengthen checking of hinge joints while hinge plates design, checking the vertical shear strength only is not comprehensive, various factors should be taken into account.

Abstract: Based on large numbers of experiment results, this paper carries out statistical analysis and proposes the probability distribution properties of the random process of strength and elastic modulus and their coefficient of variation, and develops a new prediction model of early-age strength and elastic modulus and their coefficient of variation respectively. The model can provide good prediction of the development of mechanical properties of concrete structures in aging, and it is important to evaluate the concrete structure safety and reliability in the construction period.

Abstract: As a steel pipe concrete arch bridge for example, the difference of earthquake response is analyzed and studied by considering and not considering soil-structure interaction according to software ANYSY. It provides a reference for the design of the large bridge.

Abstract: Carbon fiber (CF)is the most important reinforcement in advanced composites.Carbon fiber-reinforce cement（CFRC）possess all right mechanical properties.Carbon fiber-reinforce cement（CFRC）was produced after Carbon fibers (T700) were slightly oxidized by the method of oxidation treatment at 773K in air for a short time. The result indicates that the density of CFRC reduces, porosity enhances, the bending strength and the compressive strength enhance when carbon fibers increases,by detecting the pre-and post-treatment physical and mechanical properties of CFRC, observing the microstructure of the fracture of the Side Bend Test samples. SEM morphology shows that the fracture of carbon fibers without oxidation is pull-out failure mainly while these with oxidation is pull- cut failure mainly. In a word,Carbon fibers with slight oxidation can improve the combine state of the interface between the fibers and the matrix, and accordingly improve the mechanical properties of the CFRC.

Abstract: Excessive deflection and its long-term sustainable development has become a common disease of large span pre-stressed concrete continuous box girder bridge, but the causes of it is difficult to reach consensus. A three-spans continuous pre-stressed concrete box girder bridge is studied in this paper. The web inclined cracks near L/4 of the continuous girder bridge is simulated by FEM (finite element method), in order to explore the influences of web inclined cracks near L/4 on the overall deflection of the bridge and the effect differences of the crack width, length and numbers. The results show that when the web inclined cracks reach a certain level, it will cause a long-term sustainable development of the deflection of the bridge. Therefore, web inclined crack is the main factor that causes the sustainable development of long-term deflection of large span pre-stressed concrete continuous box girder bridges.

Abstract: Hollow core slabs have a bold design and can be used in a wide variety of structural systems, performing like floor slabs or wall panels. These slabs are economical due to geometrical and mechanical efficiency of its cross sections, allowing the rationalization of materials consumption (concrete and prestressed strands). The increase of the use of hollow core slabs within the Brazilian construction market has caused a significant boost of production, demanding the assessment of the actual strength capacity of these elements. This paper presents results relative to several hollow core slabs produced in a Brazilian factory, subjected to shear tests according to FIB recommendations. The experimental results were compared with those obtained with the equations from the Guide to Good Practice: Special Design Considerations for Precast Prestressed Hollow Core Floors, published by FIB in 2000.

Abstract: This paper demonstrates the application of both numerical simulation and empirical equation in predicting the penetration of a concrete target by an ogive-nosed projectile. The results from the experiment performed by Gran and Frew are used as a benchmark for comparison. In the numerical simulations a 3.0-caliber radius-head steel ogival-nose projectile with a mass of 47 kg is fired against cylindrical concrete target with a striking velocity of 315 m/s. In the simulation the smooth particles hydrodynamics SPH-Lagrange coupling method is applied to predict the maximum depth of penetration. For calculation of DoP and response of projectile the SPH-Lagrange method can give satisfactory results.

Abstract: The spatial analysis model of special-shaped column frame structure is established in ANSYS. The nonlinear dynamic analysis is carried out for the structure by inputting ground motions in one direction. The seismic performance of the structure under rare seismic actions was examined and whether the structure achieved the predetermined seismic aims is evaluated. The results indicates that the structure which under the 8-degree zone designed according to the codes can achieve the predetermined seismic aims under the rarely occurred earthquake actions.