Advanced Materials Research Vols. 243-249

Abstract: In constant temperature and humidity environment, the properties of shrinkage and creep for a group of plain concrete and reinforced concrete columns were observed in long-term and experimental method. The curves of concrete shrinkage and creep effect with time were obtained. Checking coefficient and type coefficient of shrinkage and creep effect were put forward in order to predict models of shrinkage and creep. Using the least square method, functions of checking coefficient and type coefficient were acquired and the prediction models of shrinkage strain and creep coefficient of concrete were obtained based on the modification of the formula of JTG D62-2004. The foundation is laid for the application of the long-term performance research in bridge structure.

Abstract: The temperature control of mass concrete is regarded to be a universal problem. Because of the heavy load of railway cable-stayed bridges, the pile caps usually have large dimensions, so the thermal stress, which is caused by hydration heat, must be emphasized. In order to study the spatial distribution of temperature in mass concrete and find a functional temperature control measure during construction, the theoretical and FEM analysis of hydration heat-thermal stress field are applied, which can improve structural reliability and provide reference for design and engineering of the similar project. Based on FEM calculation, the theoretical hydration heat temperature field is obtained. In the same time, the temperature sensors as well as strain sensors are arranged in the key position of pile cap. Then the variation of hydration temperature in concrete would be measured and recorded since the concrete is pouring. According to the theoretical simulation and the monitoring results, the time-history curve of hydration heat is obtained, and the variation of inner temperature gradient along the height direction as well as the longitudinal direction with the concrete age are studied, and the feasibility of temperature control measures is also verified.

Abstract: The research work is described about the numerical analysis and reduced scale prototype model test of Chongqing Jiayue Bridge’s PC beam, which has some special structure details. The structure’s practicality of the PC box girder’s anchorage is demonstrated through computing, at the same time, the security of the anchorage undertaking kiloton force is experimented by test. Some conclusions and suggestions are drowning through such research work which are helpful to design and construction.

Abstract: For the bridge abutment bump of express way in operation, through physical simulation experiment on the bridge-head settlement were studied to obtain the general rules of bridge-head settlement as well as the effects and parameters while grouting below the bridge-head tie-board. Grouting reinforcing method was applied to the Ning-Su-Xu West Wei River Highway Bridge; deal with the problem of bridge abutment bump. Through slurry material strength test, drill core sampling method and ground penetrating radar detect effects of grouting. Experimental results show that: By the grouting treatment below the bridge-head tie-board, which take the empty area to be filled with slurry material and make it dense, forming a whole curtain, and the density and integrity of the padding were enhanced, so, strengthening effect is very good. The practice of grouting reinforcing proves that the technique is low-cost, short construction period, and good results. So it is especially true of treating for the abutment bump of express way in operation.

Abstract: The non-stationary random responses of the moving tires induced by the road roughness in time domain were obtained, and then those non-stationary responses were treated as the non-stationary inputs to study the non-stationary vibration of a high-pier bridge under vehicles with variable speed. The effect of the two inputs on the mid-span deflections was compared with the measured responses under different parameters including vehicle acceleration and vehicle deceleration. The verified results showed that the proposed method can simulate accurately the vibration of bridge under vehicle moving with variable speeds.

Abstract: Recently, with the development of highway traffic cause and long-span bridges, the vibration performances of highway bridges due to moving vehicle loads have attracted more and more attention. The vibration of a cable-stayed bridge with steel arch tower subjected to vehicle loads was studied in this paper. Firstly, the dynamic model of vehicle and finite element model of bridge were built and the dynamic differential equations of vehicle model and vehicle-bridge coupled system were derived. Then road roughness was simulated using superposition method of trigonometric series. Finally, the bridge responses caused by vehicle loads were calculated numerically. Furthermore, the effects of road roughness, vehicle velocity and bridge damping on bridge responses and their dynamic amplification factors were studied. The results and conclusions of present study are expected to be useful for the future revision of bridge design codes and maintenance and management of bridge.

Abstract: This paper explains the static load test of a simple-support prestressed bridge. Deflection and stress are measured by the static load test of the simple-support prestressed bridge. This bridge performance and quality are evaluated by using check coefficient of the static load test.

Abstract: The test beams were overloaded 20 times repeatedly with different amplitude, and they damaged to different extent to simulate actual cracking. Strengthening the pre-damaged beams with steel plates, working situation of structure strengthened is analyzed. For the test beams strengthened, steel plates and the original structure deform harmoniously, internal force is allocated to the steel plates and the original structure with a certain proportion. In the serviceability limit state, the method of allocation of internal force is studied, and the impact of the overload amplitude, reinforcement ratio on the allocation proportion is analyzed.

Abstract: Aerodynamic stability is an issue in the wind-resistant design of long-span bridges, flutter is an aerodynamic instability phenomenon that occurs due to interactions between wind and structural motion. The Xihoumen Bridge is the second long suspension bridge in the world, the aeroelastic performance of the Xihoumen Bridge is investigated by wind tunnel testing and an analytical approach. In the case, wind-tunnel testing was performed using an aeroelastic full model of the bridge, and two section models of the bridge. Flutter derivatives of bridge decks are routinely extracted from wind tunnel section model experiments for the assessment of performance against wind loading, the analytical method used here were a two-dimensional flutter analysis and a multi-mode analysis in the frequency domain. The analytical results were compared with the wind tunnel test data; it showed that the flutter analysis results were good agreement with the wind-tunnel test data.

Abstract: For non-uniform continuous bridge in actual projects, the theoretical analysis and field testing of the dynamic response under moving vehicle are carried out. Firstly, Euler-Lagrange equation is applied to derive the vibration equation of three-axle vehicle. Then one obtains the dynamic analysis model by using the finite element method and the vehicle-bridge interaction equation based on the displacement coordination relationship of the contact between wheels and bridge. Lastly, numerical solutions are presented according to the dynamic response of the bridge, compared with the real values. The results show that: the roadway roughness and vehicle speed strongly influence the impact factor.