Applied Mechanics and Materials Vols. 94-96

Abstract: We analyze the mechanical property of strengthening RC beam by using the method of arch pasting with carbon fiber and directly pasting CFRP through numerical simulation and model test. It explains that strengthening RC girder by using the method of arch can solve the influence of beam's loading by the second time which exists in the method of pasting CFRP in strengthening reinforced concrete beams and it can improve the girder's load when it cracks and the carrying capacity; decreasing the deflection deformation and crack width and gap when the girder carries load; It can make the most use of the character of carbon fiber's high strength. The results play very important role of guiding to engineering.

Abstract: Self-balanced prestressed shell structure assembled with elements is a new spatial system composed by prestressed cable and strut elements. The structure can achieve the latticed shell design that the large span without the center column by the rational use of high strength bars and prestressed technology. This paper illustrates the design idea, stress mechanism and structure characteristics of the self-balance prestressed latticed shell. The current research status of self-balanced prestressed shell structure assembled with elements on structure form, shaping method, static and dynamic performances are briefly described in the presented work; It is seen that the research on test of structure mechanical properties, molding technology and structure dynamic performance is an urgent work to be solved in the development of the self-balanced pre-stressed latticed shell structure theory.

Abstract: The paper completely analysed the cause of bridge defect with the project profile of the Queshi bridge. And relation to different defect , the paper gave the reinforcing design and the main maintenance using the construction features.

Abstract: In this test, three models of concrete frame structure are made with the same dimension. The experiment of the models under low-cycle repeated load is studied. One of them is not reinforced for reference, and others are damaged to one certain degree then reinforced with CFRP and steel plate in completely uninstall cases respectively. This test is to study the effects of the two reinforcement methods to the seismic behavior of damaged concrete frame structure. Research shows that: the role steel plate in improving bearing capacity and rigidity of the damaged concrete frame structure is better than CFRP. Comparing with steel plate the CFRP can improve well damaged concrete frame structure ductility and energy dissipation capacity.

Abstract: In order to improve flexural behavior of concrete beams, the 7mm-diameter carbon fiber reinforced plastic (CFRP) tendons applied different levels of prestress were put in to 20×20mm grooves opened in the concrete surface of the tensile region in the concrete beams.Grooves were filled with building structural adhesive, when it solidified bending test of strengthened beams would carry out. Flexural behavior of nine RC beams strengthened with prestressed near surface mounted CFRP tendons applied different levels of prestress and one unstrengthened RC beam were studied. In these tests, bending stiffness and load-bearing characteristics of test specimens were studied. Experimental results show that the high-strength performance of CFRP have been made full use; the stiffness of strengthened beams risen notably, the maximal crack load increased by 303.17%, the maximal ultimate load increased by 237.92%.

Abstract: Pile is widely used as deep foundation in civil engineering. The dynamic interaction between pile and soil is an important problem in the field of soil-structure interaction. This paper established a model to calculate the seismic response of pile-soil couple system. In this model, pile and soil are regarded as lumped mass, soil was divided into two parts: the far region soil and near pile region soil. These two parts are simulated by different mechanical characters. A differential equation of motion of pile-soil couple system was established in the paper, this differential equation can be solved by Wilson-θ method. An example was introduced to study the behavior of pile-soil couple system.

Abstract: Advances in the research on cable domes were summarized and reviewed, such as structural improvements and innovation, prestressed mode and optimize designing of cable dome structure, dynamic and wind resistance performance analysis, construction technology, model experiment and sensitivity analysis. Some topics worthy further research were proposed, including seismic property study, improvement and innovation in construction techniques and methods, fire resistance study, stiffness analysis of structures, general design methods and software. This work will provide a meaningful reference for the design and application of cable domes.

Abstract: This article mainly introduces the structural characteristics of the multi-ribbed panel wall, the heat preservation grid wall and phosphogypsum grid wall, from their mechanical characteristics and seismic performance and so on.This paper summarizes the domestic and foreign research situation, analyzes on the problems existing in the wall structure, and clarifies the further research direction.

Abstract: We take low frequency cyclic reverse tests to three RC frames made with the same dimension. One of frames is not reinforced for reference; the others are loaded to steel yield and then completely uninstalled. One of injury RC frames is strengthened by CFRP, and we use CFRP and steel plate mixed to strengthen the other one. Then experiment under low-cycle repeated load for strengthened frames have done again, and two seismic reinforcement methods are compared by the test performance of the framework. The results show that compared to CFRP, mixed reinforcement can improve the structural bearing capacity more effectively. The frame strengthened by CFRP reflects better energy dissipation and ductility than another.

Abstract: Through shear test data analysis of 13 RC beams Strengthened with externally prestressed wire rope, shear failure mechanism was elaborated, and shear bearing capacity of reinforced beams were not only calculated respectively by truss -arch model and other simplified calculation methods, but also were compared with test data. Based on the result of comparation, shear capacity calculation method of RC beam Strengthed with externally prestressed wire rope was discussed. The analysis results show that the mechanism of the wire rope shear externally prestressed reinforced concrete beams against the shear is similar with stirrups inside beam. When the shear span ratio is less than 2.7, the static average ratio of the truss-arch model shear capacity caculation value and tested value is 1.02, and standard deviation statistics is 0.07. In another word, calculation value agree with experimental value. When the shear span ratio is larger than 2.7, the calculation value is bigger than test.