Applied Mechanics and Materials Vols. 204-208

Abstract: In the construction of prestressed concrete(PC) box-girder bridge with corrugated steel webs used cast-in-place cantilever method, the key component-corrugated steel webs are fabricated in factory first and then transported to the construction site. Because of the low out-of plane stiffness, corrugated steel webs are easy to deform in the construction, which brings many difficulties for construction. The precision of installing the corrugated steel web has a direct effect on the cross-section shape of the box-girder. So it is a key step to monitor the orientation and installation of corrugated steel web during construction. Based on the experience of some PC box-girder bridges with corrugated steel webs having been built, a method to control the installation accuracy of corrugated steel webs is proposed and some quality assurance measures are introduced in order to ensure the accuracy, reliability and security of the installation of corrugated steel web. The method can be taken as a reference in the construction of this kind of bridge.

Abstract: As one of the important traffic facilities in cities,bridges provide necessary services for the traffic in cities, but bridges that have been built in cities do not meet the requirements in durability aspect. We conduct a study about the durability of urban concrete bridges in Hebei province by this paper. In combination with the specific conditions of bridge construction, we put forward feasible measures to improve the durability of urban bridge for directiving the design and construction of bridges.

Abstract: One bridge in the southeast coast was cited as an example and the risk analysis theory was introduced into the study of vessel-bridge collision problem of the bridge. From the survey of the current situation development in the bridge site area and 5000 tons collision-prevention requirements, the annual probability of collapse of the bridge in the year 2020 is over the criterion by the AASHTO model algorithm. In accordance with the AASHTO acceptance criteria for vessel-bridge collision risk, the mentioned vessel collision risk of the bridge was not acceptable. In this paper, based on “m” method and FLAC3D program, the research on horizontal bearing capacity of pile group of one bridge in the southeast coast under vessel impact is performed, and the effects of the anchor is considered, which is significant for the risk analysis and bridge anti-collision study.

Abstract: Climate changes in recent years have caused a trend of increasing rainfall in Taiwan. In addition, the rivers of Taiwan flow down steep slopes with rapid currents, and the flow is extremely turbulent in particular segments of the rivers, causing pile scours that affect the stability of bridges in the area. Based on turbulent flow theory, this paper establishes an estimation model for the pier scour depth limit of suitable bridges crossing rivers in Taiwan, according to the characteristics of the stagnation point and separation point of fluid mechanics. A bridge in northern Taiwan is analyzed according to measurements, confirming that the channel scour formula suggested in this paper demonstrates sufficient accuracy. Additionally, lateral pushover analysis is performed on the bridge to understand the seismic durability of the bridge structure following a scour.

Abstract: Based on the characteristics of local piers scouring after built the sediment control dam in the downstream of the bridge, by the monomer model experiment of flume, sixty groups of local piers scouring experiments have been carried on.The principle and the influence factors of the local piers scouring have been analyzed. The results of series model experiments show that, with the sediment control dams, the local scouring of the piers, on one hand, is influenced by the approach velocity, down-shearing vortex, dimension of the piers, diameter and gradation of the bed sand; on the other hand, it is affected by the elevation of the dam and distance between the pier and the dam. Therefore, the concept of “control slope” is introduced in order to reflect the impacts of the sediment control dam to the piers. Based on the theoretical deduction and dimensional analysis, the equation, which is used to calculate the local scouring with no-uniform bed sand, is acquired by multivariate regression analysis, has been testified by the flume experiment and has got a good result. The optimum value of control slope and the equation of local piers scouring with that dam provide valuable references for bridge flood-control design of the shallow foundation with downstream sediment control dam.

Abstract: Bridge tower, time-varying temperature field, heat transfer analysis, finite element model. Abstract. Long span suspension bridges are subjected to daily, seasonal and yearly environmental thermal effects induced by solar radiation and ambient air temperature. This paper aims to investigate the temperature distribution of a tower of a long span suspension bridge. Two-dimensional heat transfer models are utilized to determine the time-dependent temperature distribution of the bridge tower of the bridge. The solar radiation model is utilized to examine the time-varying temperature distribution. Finite element models are constructed for the bridge tower to compute the temperature distribution. The numerical models can successfully predict the structural temperature field at different time. The methodology employed in the paper can be applied to other long-span bridges as well.

Abstract: The system of a simply continuous beam was looked on as one span beam with several internal elastic supports of inexhaustible stiffness. There were two types of models such as the dynamic models by a moving concentrated force and by a moving mass. A three-span beam was introduced as example solved with the present model by a moving concentrated force and FEM, which verified that the present model was correct. Two cases of the example bridge by a moving concentrated force and by a moving mass were considered. The results indicate that mass of the moving load has little influence over the dynamic responses of the simply continuous beam bridge.

Abstract: The plate type elastomeric pad bearing is the most commonly used in highway bridge bearings. In the seismic design of bridges, the horizontal rigidity of the bearing is an important calculation parameters. The specific values of each parameter in the formula are not clear, and it can not provide a clear computation measures, although the formula of horizontal rigidity is given in the specification. Against Series bearings in plate type elastomeric pad bearing for Highway Bridge (JT/T4-2004), the People's Republic of China Communications Industry Standard, the structural parameters of the bearing are systematically introduced, including the shape factor, the bearing thickness, the thickness of the single-layer rubber and the total thickness of rubber layer. The methodology and detailed steps of the bearing horizontal rigidity are then analyzed and summarized by the formulas above. At last several examples of the different type of bearings are given. Some reference are Provided for the calculation of the stiffness frequently of plate type elastomeric pad bearing which are frequently used for highway bridges.

Abstract: Test research on behavior and theoretical analysis were carried out to ensure the in-service safety for the reason of diseases of existing double arch bridges[5]~[6]. Combing with a practical example of Menggong Bridge present situation, the performance was detected and the actual bearing capacity was checked through multi working conditions loading test. The finite element calculated model was established using the software MIDAS to simulated analyze internal forces and deformations. The comparison showed that the calculated result was well agree with experimental data, the structural design was reasonable and the flexural stiffness and bearing capacity were enough. The results also indicated that Menggong Bridge should be reinforced for the diseases, and the test and finite element calculation model were effective and reliable.

Abstract: This paper studies air permeability, water absorption and chloride resistance properties of the normal concrete (NC) and the high performance concrete (HPC) adopted in the Yu-Cheng Bridge, Zhejiang Province. The air permeability and water absorption were measured by Autoclam, while the chloride resistance were tested by RCT after accelerate chloride ingression in the salt spray cabinet. The relationship among the air permeability, the water absorption and the chloride resistance of both kinds of concrete were analyzed. According to the result of Autoclam, HPC shows better resistance abilities of air permeability and water absorption, and this indicates that HPC is denser than NC. RCT shows that the chloride resistance of HPC is better than that of normal concrete.