Applied Mechanics and Materials Vols. 351-352

Abstract: With the fast development of economy, science and technology, concrete has been widely used in bridge construction. But the problem of concrete bridge structure crack is still an important issue in bridge construction in China. How to combine the bridge foundation theory with the practice of construction to solve the problem of concrete bridge structure crack is the key to guarantee the quality of bridge construction. This paper focuses on the cause analysis of concrete bridge structure cracks and the treatment countermeasures are put forward.

Abstract: The combination of a number of construction experience, which is based on the analysis of different parts of the fly ash foam composite light wallboard wall cracks. Appropriate preventive and remedial measures were put, specific elaboration was done, which were used to guide practice and reduce light wallboard wall cracks.

Abstract: Anchoring the external prestressing to the bridge end block is one of the key issues for strengthening of existing concrete bridges. This paper presents an innovative technique to fix steel brackets to the sides of the end block by two transverse pretensioned through-rods and three expansion bolts in both friction and shear pattern. In order to validate the technique, two steel reinforced concrete specimens (J1 and J2) fixed with experimental steel brackets are prepared and an experiment investigation has been carried out. Two sudden failures have been observed. The failure patterns of expansion bolts in J1 are pullout failure and shear failure, and two transverse pretensioned through-rods have large yield deformation. The failure patterns of expansion bolts in J2 are similar, but the failure patterns of two transverse pretensioned through-rods are shear fracture. The relationship of force and slip is linear but with two different slope when the load less than 2000kN in both J1 and J2.

Abstract: To study the effect of prestress level on beam for its flexural property, through comparing of the stress property of non-reinforced beam, non-prestressed fiber beam, and prestressed fiber beam. The experimental results show that non-prestressed fiber makes little difference in improving beams flexural property, while prestressed fiber has improved beams cracking load, yield load, bending rigidity greatly.

Abstract: 5 masonry columns were strengthened by Sprayed Glass Fiber Reinforced Polymer (SGFRP) in this paper, and a research of the seismic behavior of them tested by eccentric loading experiment was presented. The failure modes of the strengthened masonry columns were illustrated and strengthening effects of them were discussed. The results showed that the bearing capacity of the reinforced columns increased greatly, and the ductility of them also improved significantly. Comparing the strengthening effects of the columns when the thickness of SGFRP and the number of glass fiber are different, some reasonable reinforce suggestions are proposed.

Abstract: Assembly technology using prefabricated reinforced concrete (RC) members can effectively improve the seismic performance of existing masonry buildings. In this study, an existing masonry wall is enhanced by two pieces of prefabricated RC panels bonded on both surfaces of the wall. In order to guarantee the co-action between RC panels and the masonry wall, three techniques are employed, specifically, RC dowelling keys, grouting agent, and post-cast concrete bands. To investigate the interaction and force transmission between the two components, this study builds sophisticated finite element models and conducts nonlinear analyses to simulate the quasi-static cyclic tests. It is demonstrated that the proposed retrofitting technology effectively improves the seismic performance of existing masonry walls. The strength of existing walls increases 3-4 times and the stiffness increases 2-3 times, so that the requirement of current seismic design code is satisfied.

Abstract: Beijing Hutong has been the symbolic building of old Beijing city for hundreds of years and today it still accounts for a large proportion in the old buildings. In this article, Appraiser work of structural safety reliability is firstly done for the selected Hutong buildings. Then Analytic Herarchy Process is used to do the weight analysis of renovation schemes focusing on four different aspectsstructural safety, historical value, architectural value and cultural and artistic valueso as to get a more reasonable renovation and Appraiser conclusion. The Appraiser method used in the article will provide some guidance and references for similar buildings renovation and identification.

Abstract: Base on a practical project, the site-test Research on s Capacity of Bonding Interface Between New and Old Concrete was carried out with three different disposal ways, which is Roughening ,slotting and planting bar. The test process and phenomenon were described, The conclusion is that Planting bar is a more effective way to improve the bearing capacity between the new and old concrete surface.

Abstract: The old prefabricated reinforced concrete buildings have been designed with old standards that are lower than the present design code provisions. These buildings are likely to be vulnerable to severe damage or total collapse under strong seismic excitations. Hence, it is necessary to evaluate these buildings seismic performance and to retrofit them using appropriate methods. Buckling-restrained brace (BRB) is a kind of prospective energy dissipation component. As a brace, it is also a lateral force resistant member. Based on the characteristics of prefabricated frame and BRB, the time history analysis of a prefabricated frame strengthening by BRB is carried out by using software ANSYS to input the seismic wave. Then, the seismic behavior of this kind of frame is studied. It is observed that the seismic response of the retrofitted structures reduces significantly in comparison with the corresponding original structure without any retrofit measures.

Abstract: BFRP has excellent strength, durability, thermal properties and economic cost. To test seismic performance of short columns strengthened with BFRP. Low cyclic loading test was conducted on one comparative short column and two RC short columns strengthened with BFRP. The test shows that short columns warped by BFRP show excellent failure modes, shear capacity, ductility and energy dissipation. As a new fiber reinforced plastic, BFRP has a good prospect in the area of seismic strengthening for its low cost and comprehensive mechanical properties.