Advanced Materials Research Vols. 368-373

Abstract: According to water power, structure and foundation conditions of aqueduct, it has established aqueduct safety assessment indicator system and standards. Based on statistical learning theory, support vector machine shifts the learning problems into a convex quadratic programming problem with structural risk minimization criterion, which could get the global optimal solution, and be applicable to solving the small sample, nonlinearity classification and regression problems. In order to evaluate the safety condition of aqueduct, it has established the aqueduct safety assessment model which is based on support vector machine. It has divided safety standards into normal, basically normal, abnormal and dangerous. According to the aqueduct safety assessment standards and respective evaluation level, the sample set is generated randomly, which is used to build a pair of classifier with many support vectors. The results show that the method is feasible, and it has a good application prospect in irrigation district canal building safety assessment.

Abstract: To construct a finite element model of concrete-filled steel tube column which is suitable to practical engineering analysis, a double-beam (DB) element is proposed. The element is made up of two coinciding beams which simulate steel tube and kernel concrete respectively. The parameters analysis results show that a concrete-filled steel tube column should be divided into four or more DB elements to make the error of fundmental frequency less than 5%. Moreover, based on design codes of the concrete structures and steel-concrete mixed structure of tall buildings, a simplified constitutive model of kernel concrete is developed to consider the confinement effects of steel tube on the concrete. The results of numerical example show that the P-△ curve based on the simplified model is consistent with the experimental results, but the ultimate bearing capacity is less than experimental results. Therefore, the model has a reasonable reliability and can be a reference for similar engineering design analysis.

Abstract: The fracture theory of soil was a new developing problem in recent year. In this paper, the basic principle of fracture mechanics and the strength theory of soil were combined, and the soil-cracking strength theory was adopted to build a constitutive relation for cracked soils. In order to use such theory and to analyze how the cracked soils effect on retaining structure, we developed an elastoplastic finite element program. Finally, the calculation results from this program were compared with the surveying measured in model testing.

Abstract: This paper studies the impact performance of concrete filled FRP-steel tube which is a composed structure made by filling concrete into steel tube and wrapping outside with fiber reinforced polymer (FRP) sheet. Numerical simulations have been conducted to study the dynamic response of fixed-pined supported beams of concrete filled FRP-steel tubes. The finite element models of concrete filled FRP-steel tubes are established to analyse its lateral impact dynamic characteristics under different loading situations, with respective kinds of FRP and thicknesses of steel tubes. The impact force and displacement histories were recorded. Comparing to the traditional concrete filled steel tube structure, the concrete filled FRP-steel tube indicates a promising structure with more advantages in the mechanical and constructional performance. Especially with its higher loading-carrying capacity and better toughness, it is more adaptable for the structures subjected to accidental impact load. Analytical solution is compared with experimental result to show the correctness and the effectiveness of present study.

Abstract: With the rapid consumption of natural resources, there is a growing concern about sustainable development. More than 6 billion tons of concrete are produced annually for various construction purposes with limited life expectancy. In addition, increasing cost of construction and demolition of concrete structures in densely populated areas is a great concern for the future. One of the best solutions to tackle these challenges is to increase the life expectancy of the structures. Residential structures and important civil structures are typically designed for a life span of 50 and 100 years respectively. However, the life expectancy of structures can be increased to several hundred years with careful planning and proper design. Cost of the concrete materials is not a considerable amount compared to the total cost for construction of reinforced concrete structures. Doubling the concrete materials cost may only increase the total construction cost by few percent but it can increase the life expectancy of structures significantly. In this work, a comparison between ultra durable concrete mixes with normal high strength concrete in terms of cost, mechanical and durability aspects is presented. Ultra durable concrete has superior qualities which makes it a favourable construction material for future structures.

Abstract: Diaphragm beam has grate influence to load transverse distribution factors of T-beam bridge. Two steel T-beam bridge models were made in this article, one have diaphragm beam and the other one have not. Concentrated load was applied to both of them, and mechanical analysis of the T-beam bridge model was carried out by finite element software. Compared with experiment data and theoretical data, it shows that: when the concentrated load was applied to mid-span of 1#,2# and 3# beam of the two kind bridges, the 1#,2# and 3# beam load transverse distribution factors of T-beam bridge without diaphragm beam is larger than that of T-beam bridge with diaphragm beam by 19.3%~23.2%、25.3%~30.6% and 48.1%~50.1% respectively.

Abstract: The main bridge structure of the bridge engineering cross Yitong river, on the 102 national road, is a three-Span flying swallow type special-shaped CSFT arch bridge. This paper introduces the design, process and a result of the dynamic model test of the CFST arch bridge, and introduces the dynamic test of the bridge.

Abstract: Frames consisting of reinforced concrete column and steel beam (RCS) is a new type of composite structures. Background of the research and application of the RCS composite joints and composite frames are overviewed detailedly in this paper. Then the research evolution of the RCS composite joints including experimental research and numerical simulation in America, Japan and China are described in detail. Finally some problems existing and the development directions of research on RCS framing systems in future are pointed out.

Abstract: The paper analyses the damage condition of transport infrastructure in Wenchuan earthquake and eplores the possible difficulties in post-disaster reconstruction. Next,the thesis put forward a feasible financing model for the post-disaster reconstruction, which providing a basis of decision making for reconstruction work.

Abstract: After boundary conditions of member and thermal parameters of materials are determined, ANSYS software is utilized to analyze the maximum temperature distribution in the member under different fire duration. The equivalent cross-section economization method is given to calculate residual bearing capacity of RC member after exposure to high temperature, here, strength of reinforcement is considered as invariant, and the original section area is regarded as reduced. The numerical results are in good agreement with the experiment results of other reference, so appliance of the method is proved, Based on these, some parameters have significant influences on reduced coefficient of residual bearing capacity, such as sectional dimension, fire duration time, strength of reinforcement and concrete，ratio of reinforcement，thickness of fire-protection layer, which are analyzed and theory basis is supplied on safe monitor, repair and reinforcement of RC member after exposure to high temperature.