Advanced Materials Research Vols. 838-841

Abstract: The influence of AC frequency , the content of sodium sulfate and curing time on the electrical resistivity of cemented soil was studied. Firstly, the impedance modulus of cemented soil blocks were measured and their electrical resistivity were calculated; then the primary and secondary factors influencing on the electrical resistivity of cemented soil were determined through orthogonal method; finally , the influence of three factors on cement soil resistivity was discussed qualitatively. It is found that the primary and secondary factors influencing on the electrical resistivity of cemented soil are the curing time, the content of sodium sulfate and the frequency. The electrical resistivity decreases with the increases of AC frequency and content, whereas increases with increasing curing age.

Abstract: Basket handle arch bridge with reinforced concrete shortens the distance between the arch rib compared with parallel arch rib bridge, improves the lateral stability, predecessors have done a lot of research on basket handle narrow arch bridge, but the study of wide span arch bridge is insufficient, conduct load test on a wide basket handle arch bridge which 33m wide and mainspan is 90m, the test results show that the large width-span ratio arch bridge has higher bearing capacity, but vertical bearing capacity is not improved, the dynamic coefficient increases when the speed is higher than 30km/h, the measured dynamic coefficient at jumpy driving is relatively large, the dynamic coefficient is significant when jumpy driving speed is 10~15km/h.

Abstract: Through the checking comparison of example bridge, to analysis the major causes of the cracking and too much deflection for prestressed concrete continuous box girder bridge. Calculated weak position and the current presence of cracks in the bridge position basically consistent, so cracks mainly caused by the prestress loss, concrete creep and the temperature effect, the structure stiffness weakened after cracking, then the actual mid-span deflection is greater than the calculated values bound. Therefore, the cracking and too much deflection appear simultaneous and mutual promote. The view that by improving the mechanical behavior of box girders, design parameters optimization, just the fundamental solution to cracking and too much deflection, also, several key issues need study to be addressed.

Abstract: With the background of bridge on Riverside Avenue cross over Yangtze River tunnels in Nanjing, studies on the influence of bridge construction and operation on the Yangtze River tunnels are as followed. First, safety control standards of Yangtze River tunnels are presented according to safety situation of the tunnel and the deformation property of super large shield tunnels. Then bridge construction and operation process is simulated to study the engineering influence on adjacent Yangtze River tunnel, to which the excavation of bearing platform foundation pits and piles, and bridge loads are considered. Safety state of Yangtze River tunnel during bridge construction and operation period is estimated based on the safety control standards and numerical simulation results. Construction scheme is optimized, and suggestions are also given to reduce harmful effect on the tunnels brought by construction of the bridge.

Abstract: Based on the situ results of Self-balanced Method and Anchored Pile Method on the piles of Qingdao Gulf Bridge, the test method of them have been contrasted in same cite. Compared with anchor piles method the self-balancing test is simple way which saves money and time. And the load-displacement curve obtained from the self-balanced test is closed to anchored pile test; from the view of the sides shear resistance, the side resistance below the load cell in Self-balanced Method is less than the value in Anchored Pile Method while the value under the load cell is more than it. The proportion which tip resistance occupied in self-balancing test is more than the traditional anchor piles method, it should be considered in pile design.

Abstract: Because fatigue load of bridge structure under the highway and light-railway loads has not been specified in current design codes, it is necessary to study the fatigue load of cable-girder anchorage structure of the highway and light-railway cable stayed bridge. Take Chongqin Hongyan Jialing River bridge as the subject of investigation, the fatigue load of cable-girder anchorage structure is computed through MatLab program developed by Monte Carlo method and the rain flow method. According to the traffic flow surveys on the load spectrum, the fatigue load of cable-girder anchorage structure was calculated accurately by the MatLab program. Through comparison with the calculation results of the MatLab program, a fatigue load calculation method used equivalent fatigue vehicle based on the Palmgren-Miner linear cumulative damage theory is reliable and accurate.

Abstract: In order to evaluate the reliability of existing bridges ,based on maximum value of the load and model of probability calculation of resistance attenuation, according to the data of the bridge which actually collected, and by using the ADINA finite element software to build the finite element model of considering the damage detection of beam bridge. The component and system failure criteria are determined on the basis of the bridge load-bearing characteristics.The Time-dependent reliability of the system by using the probability calculation model for assessing the maximum value of the load and resistance attenuation can be obtained. The result shows Changes in the process of reliability prediction of bridge , the correctness of reliability calculation model be verified; the correctness of the ADINA model be validated; Also confirmed the feasibility of prediction model; to obtain the main influencing factors of reliability of existing bridges.

Abstract: This paper examines the bearing capacity and stability of a catenary axis uniform cross-section multi-span stone arch bridge with solid spandrels after strengthening and widening, in the light of the Code for Design of Highway Masonry Bridges and Culverts (JTG D61-2005) published by the Ministry of Communications of the People's Republic of China. Taking the West Ulanhot Large Bridge built in cold area of Inner Mongolia in 1960s as an example, the effect of dead load, live load and temperature variation after and before strengthening as well as multi-arch action were considered. Through calculating the bearing capacity and stability of stone multiple arch bridge, compared with the results of loading test and follow-up survey on operation condition for many years, the safety and effectiveness of strengthening scheme are evaluated.

Abstract: Under the process of numerical analysis of fatigue failure of panel of highway reinforced concrete bridge , numerical analysis method is put forward , which can simulate process of fatigue damage degradation of the bridge deck under the vehicle load . In the first , complex vehicle load is equated simplistically on the basis of the national related tests and research with formulating load spectrum reasonably; Then modeling analysis by Midas software , it carries out that fatigue constitutive relation between steel and concrete material is correct among the flexural member under cyclic load ; Finally , an actual reinforced concrete bridge panel is predicted fatigue life and made fatigue numerical analysis . Results show that the fatigue life of the panel meets the requirements; Building material fatigue constructive relations can simulated rule of mechanics performance attenuation of steel and concrete effectively in the course of cyclic loading.

Abstract: Bridge static load test is a conventional method to ensure the safety of bridge, but time-consuming and inconvenient in certain situation to implement. This paper attempts to use photogrammetry method to achieve deformation measurements in the bridge static load test, which is based on time baseline method. using image correlation matching for distance measurement, and using the edge recognition of the targets and ellipse fitting to get the conversion factor of in-image and actual distance. The validation of laboratory experiment and engineering application proved its strong practical value with high accuracy.