Advanced Materials Research Vols. 639-640

Abstract: Common used Non Destruction Testing (NDT) technical is introduced. Combined with the bridge common damage problems and NDT present research situation and the current research trends, summed up the NDT detection contents used in bridge engineering. The NDT methods in theory study and engineering application development trends are forecasted. It will provide references for the research of NDT technology. Finally, modern sensor technology and wireless communication technology are suggested to be used in bridge NDT technology. Also the bridge health monitoring system is integrated into to provide the technical support for the bridge whole life design.

Abstract: The ultrasonic method and the impact-echo method are two kinds of nondestructive test method (NDT), which are widely used, not only for concrete component, but for masonry structures. However, it is hard to detect the flaw in the concrete composite component if only with one kind of detection method. In this study, the principle of ultrasonic method and impact-echo method are outlined. And an attempt of a new method is taken, that Ultrasonic method together with Impact-echo method is used in detecting the deflection in Concrete Composite Component. It is proved that the result of this new method is more accurate and stable than that of only using ultrasonic method or impact-echo method. Introduction Introduction

Abstract: With the wide applications of post-tensioned concrete structures, the grouting conditions of tendon ducts are paid more attentions. In order to accurately assess the internal grouting quality of the grouted tendon ducts and certainly guarantee the lifetime of prestressed concrete structures Ground Penetrating Radar (GPR), which is a kind of nondestructive testing (NDT) method, has been applied to inspect and evaluate qualitatively and quantitatively on the grouting defects, respectively. A series of in-house tests were carried out for simulating the defects of tendon ducts by foams with different sizes. The results show that the GPR technic was one of the optimal methods for inspecting the internal grouting quality of grouted tendon ducts for post-tensioned concrete structures.

Abstract: According to experimental record of bridges in use, more and more damage bridges have appeared, and the most common and severe defect is the bridge damage and cracking problem, which has seriously affected the normal usage of bridges. Analyzing the disease cause of defective bridges more effectively and deeply, in order to optimize the design and construction of bridges becomes the urgent problem in the engineering field. The study is based on the design, construction data and experimental record of the bridge.A non-linear mapping function from multiple input data (the deck elevation of each element in destructing) to multiple output data(the change of pre-stress) is constructed within BP neural networks. Based on the theory of continuous function, the convergence is disadvantageous between 0 and 1. The study shows the expected output data between 0.05 and 0.95 are better for convergence. According to the real data of bridge floor line change in process of destruction, the released pre-stresses are recognized, and the real pre-stresses in existence are calculated by scheme of cable design. The study not only offers reliable scientific basis for analyzing the disease cause in the bridges, but also is helpful to design of the bridges having same structural style.

Abstract: To analysis the reliability of Dongjiang Bridge, a steel truss bridge stiffened with rigid cables, a new analysis method that combined with each advantage of some common reliability computing method was put forward, which could get the probability distribution and numeric attributes of complex bridge structure's response expediently, and then get the reliability index and failure probability. A stochastic finite element model was established to analyze this bridge, in which some parameters such as material, geometric dimensioning, loads, and so on, were simulated as stochastic variables. The analysis result show that the lowest reliability index of main member bar's stress is 5.10, more than the allowable value 4.7, and the corresponding failure probability is 1.71×10-7. The reliability index of mid-span deflection in serviceability limit states reach up to 6.99 and its failure probability is 1.53×10-7. All results indicate that the strength and stiffness of Dongjiang Bridge has higher reliability.

Abstract: This paper describes principle and working mechanism of the steel tube confined concrete, to analyze impact factors of steel tube confined concrete strength. By the studies, presents several solutions to improve the strength of steel tube confined concrete, fully execute the behavior of steel tube and filled-in-concrete, strengthen the interactions between steel tube and filled-in-concrete to provide theoretical basis for the design and use of steel tube confined concrete.

Abstract: Based on the ANSYS platform, set up five finite element models of beam-column joints strengthened by top and seat angles, analysis its seismic performance and discuss how the width and thickness of the angle affect it. The results showed that: (1) Strengthened by top and seat angles can effectively reduce the stress of the weld in the column, relocated the plastic hinge, increased the ductility and the energy dissipation capability of the structure. (2) As the width and thickness of the angle increase, the bearing capacity of the joint improved, but its hysteretic behavior and energy dissipation were decreased.

Abstract: Concrete-filled steel tube structure is one of the important load-bearing systems of modern high-rise building.The research indicate that concrete-filled steel tube structure has a good static and seismic performance,and concrete-filled steel tubular component is always used as axial compression and compression-bending component.However,what about the mechanical behavior of this combinational structure (concrete-filled steel tubular columns with steel bone built-in) So there is a new type of special-shaped cross-section of composite structure,that is the T-shaped concrete-filled steel tubular columns with steel bone.The research about this structure is less throughout domestic and foreign.So the axial compressive experiments of six T-shaped concrete-filled steel tubular stub columns, five with and one without steel bone, were carried out. The effects of tube confining factor, bone indicator on the axial compressive behavior of the columns are analyzed. Experimental results indicate that the ultimate strength of the T-shaped steel tubular stub columns with steel bone increases, can be increased by 71.7%.And that the setting of steel bone improves the confinement of the concrete core, delays or even avoids the local buckling of the steel tube before the stress attains the yield strength. The ductility of the columns is also greatly increased.And at last in this paper, use of static equilibrium conditions and limit yield conditions,and in reference to literature[1],the calculation equation of compression capacity of this combinational column is derived.Moreover,calculation results according to the formula in this paper are in good agreement with the experimental results. The conclusions might be used as reference to structural design and plan.

Abstract: More attention has been paid on the technology of BFRP in civil engineering due to it’s unique properties, such as high strength-to-weight radio, good resistance to corrosion and convenient to construction. In order to study the properties of BFRP sheets confined concrete column ,we did it through three groups of columns subjected to axial loading tests and FEM analyses, mainly considering the effect of spacing of straps of BFRP sheets confining concrete column.The results shows that the axial compressive strength and ductility of concrete column winded by BFRP straps have all increased and the process of destruction of concrete column wrapped by BFRP is longer than that of the unconfined concrete column.

Abstract: To study the mechanical property of concrete column confined by GFRP, we conducted 6 groups of specimens under axial compress. The influences of GFRP wind mode and layers were taken into account. According to the results, bearing capacity and ductility of the spiral winding specimen was improved greatly. The bearing capacity of the 6° spiral winding concrete column’s improvement is 28%, more than it of 0°. The fiber polymer’s utilization ratio can be improved greatly when column were combined with all spiral wind. Strengthen the concrete column of ±15°cross spiral winding pretend to be stronger capacity of bearing axial press than it of 6° spiral winding, but limiting strain tends to be lower. Shearing crack often happens at the 45°of the specimen, so shearing failure can be prevented effectively by GFRP (45°).Effective deformation and strength can be provided by FRP at the direction of axial and circular, and the reinforcing steel bar in concrete column can be substituted partially.