Advanced Materials Research Vols. 671-674

Abstract: The reinforced concrete simple-supported beams are made, applied load continuously until there product crack in them. Then, we select the binder to repair the crack and load them secondly. We verify the performance of the binder by experiment.

Abstract: Based on micromechanics, an elastic-plastic-brittle damage model of concrete beam strengthened by bonded steel plate is proposed by considering the aggregate gradation curve algorithms and the heterogeneity. In this model, the concrete beam strengthened by bonded steel plate is taken as a five-phase composite material that consists of the mortar matrix, coarse aggregate, bonds between matrix and aggregate, steel plate, and the adhesive layer between steel plate and concrete beam. Through the numerical investigation on bending failure of concrete beam strengthened by bonded steel plate under external force, the results show that the model can clearly simulate microscopic plastic yield, and the initiation and extension of crack. The strength of the steel plate is relatively lower and it firstly yield and damage, then the bending stress born on the steel plate is transferred to the concrete beam. This results that the inner cracks of concrete beam increase rapidly and coalesce until the failure of the whole specimen. The final failure mode of concrete beam strengthened by bonded steel plate is the ductile bending failure.

Abstract: When the concrete and steel combined composite beam is exposed to high temperature, concrete could delay temperature rising of steel by covering or increase heat capacity of structural member. For becoming of structural reinforcing by unification between materials, fire resistance rate of composite beam would be higher than simple steel beam. The temperature rising of exposed steel of composite beam is directly related with section shape and exposure length of steel. In this study, fire resistant tests were carried out for composite beams and steel beam with same thickness of spray-type fire resistant materials in standard fire, and after that, temperature histories were analyzed and compared with shape factor. The correlation between steel temperature and shape factor was showed very high. This result suggests that if it can be predict the comparative advantage of member by factor which cause the performance enhancement, it could be conclude that an Standard Accreditation method can be adjust to members without individual certificate of accreditation.

Abstract: A full-scale, three-storey wood frame structure had been tested in-situ to investigate the changes of dynamic properties due to artificial damage. Beams and braces of the test structure were removed, to simulate damage, and then reassembled, to simulate rehabilitation. Free vibration tests were performed during every stage of the tests. The natural frequencies and damping ratios were obtained using modal parameter identification technique based on the Hilbert-Huang Transform. It is shown that, when the structure is damaged or rehabilitated, the natural frequency changes in accord with the structural stiffness in general while the damping ratio varies irregularly.

Abstract: A nonlinear analytical approach for evaluating the inelastic buckling and residual strength of column member is presented in this study. A steel column member subjected to an axial compression load will shorten in the direction of load. If the load increased until the column buckles, the shortening will stop and the column will suddenly bend or deform laterally and may at the same time twist in a direction perpendicular to its longitudinal axis. However; before final buckling or collapse, steel column member has a tendency of plastic deformation. The issue has been much discussed along with the evaluation of plastic deformation capacity and restoring force of column members in the large deformation range following inelastic post-buckling. In order to predict the inelastic buckling behavior of the member, the load-deformation relationship needs to be identified in the whole process. To verify the accuracy of the nonlinear finite element analysis, compression test on an H-shaped steel column member was carried out and both inelastic deformation and the relationship between load-displacement curves were compared.

Abstract: Based on unified strength theory solution of thickness cylinder, according to the introducing concrete strength reduction factor and equivalent restriction factor, this paper deduced the axial compressive bearing capacity formula of concrete-filled double skin steel tubular columns of octagon section. Compared the results of the paper with the experiment results，both coincide in good condition. The results show that the theoretical formula are correct and viable. The theoretical formula is expected to provide a theoretical foundation to the research of concrete-filled double skin steel tubular columns of octagon section.And it provides references for the engineering design.

Abstract: This paper describes the research on CFST and SRC and makes a comparison between CFST and SRC in the earthquake and fire. Get the comparison of horizontal displacement and rotation of the beam and column nodes and the comparison of CFST and SRCs’ fire resistance. Providing experience for the future engineering research.

Abstract: Diaphragm is often used in box-girder bridge for controlling warping stress such those in midspan or transferring strong bearing reactions such those in ends of span. The results of a crack investigation of box-girder bridges showed that vertical cracks can be found on most diaphragms and formed in early stage of the concrete hardening. Temperature caused by hydration heat is an important factor for these cracking. Therefore temperature field prediction for the diaphragm is significant to prevent the concrete diaphragm cracking. In this paper, three-dimensional finite element analysis software ANSYS is used for simulating 3D temperature field of diaphragm of the concrete box girder bridge in all stages of construction. By calculating space temperature field of the diaphragm in different time hydration heat of the law is analyzed, combined with the measured temperature a comparative analysis to verify the validity of the temperature prediction method is conducted. The results show that simulation method is effective and accurate enough to predict the time-varying temperature field of the diaphragm.

Abstract: The prestressed concrete deck-tied arch bridge doesn’t only have a long span, good appearance and economy, but also have the characteristics of low requirements to the foundation. It changes traditional tied arch bridge into deck-tied arch bridge, which looks like sunflower-shaped arch and prestressed steel strands are embedded in box girder on the top of the arch. Taking Yingbin Bridge as engineering background, the reasonable analysis model was established and behaviour of the bridge under design load was analyzed. The results shown that the design project is reasonable, prestressing force embedded in box girder can balance horizontal thrust in arch bridge effectively, improving the internal force of the main arch ring.

Abstract: Based on a project of "Study on Bearing Capacity and Design Method for Curved PC Box Girder Bridge"(number: 03-01K), which came from the Communications Department of Shaanxi Province, temperature gradient effect of curved concrete box girder was researched. Using Finite Element Method (FEM), the effect of temperature gradient stipulated in several codes (Britain bridge standard, Australia bridge specification, New Zealand bridge standard, Japan bridge standard, America bridge specification and China bridge code) were analyzed and compared with. The results show that the calculated stress caused by temperature gradient is relatively unfavorable according to the bridge specification of China, which indicated that it is safer to adhere to Chinese code.