Advanced Materials Research Vols. 250-253

Abstract: Nowadays, with the rapid development of the traffic infrastructure construction and the growing of the traffic flowing and speed, the vehicle-bridge coupling vibration research has become the focus of the bridge engineering study. The dynamic response of the bridge under the traffic flowing is one of vital parameters for the vehicle-bridge coupling vibration analysis. In this paper, a methodology, employing the radar speed gun, the video recorder, and the dynamic strain tester in combination with manually recording is used to continuously and detailed investigate the traffic loads on the expressway bridge within 24 hours a day. With this approach introduced by this paper, all the critical parameters, such as the vehicle type, speed, traffic lane, the arriving time of the traffic and the bridge-vehicle dynamic interaction are all recorded. In this investigation, firstly the dynamic responses of 8 pieces of beams of the bridge under 5650 individual vehicles driving through the bridge are recorded, secondly statistics analysis are made for the record of each beam, and finally the space-time distribution laws of the dynamic response of the bridge under the traffic flowing are studied extensively. The result of this study could provide helpful theoretic guidance and supporting data for the vehicle-bridge coupling vibration research.

Abstract: Based on plane strain theory, the formula for calculating the tensile stress on the interface between the steel tube and concrete under the axial pressure was derived, and the stress distribution coefficient K was analyzed. Practical formula for calculating the interfacial tensile stress of CFST members under low stress condition was fitted. Using the fitted formula the interfacial stress calculation process can be greatly simplified, and the results have enough assurance. This formula can be easily applied to CFST members’ interfacial stress calculation.

Abstract: The application of the analytical hierarchy process (AHP) to the risk analysis of deep excavation was investigated. Firstly, the occurring probabilities of various risk factors during deep excavation were calculated. Secondly, the aftereffects of the risks were concluded by consulting the experts. Thirdly, the weight of each risk factor was obtained by AHP. Finally, the total risk of deep excavation could be evaluated by fuzzy complex evaluation. This risk analysis method was applied to evaluate the total risk of a real deep excavation, and the exemplification verified its feasibility.

Abstract: By a static and repeated pull-out experiment between steel bar and recycled aggregate concrete, and bond-slip curves between recycled concrete with different recycled coarse aggregate(RCA) replacement percentages were recorded. Based on the analysis of the experimental results, replacement percentages of recycled concrete, cover thickness, anchorage length, concrete strength and loading method was investigated. At last, the bond-slip constitutive relation was also discussed.

Abstract: Results of experimental study on fire resistance of four concrete encased steel (CES) columns are presented. The four columns have the same steel section and reinforcements but different load intensity and load eccentricity, which were the key factors for fire resistance of CES columns under fire condition. The tested results are utilized to study the effect of various parameters on thermal and structural response of CES columns. Spalling of CES columns under fire condition are also investigated. Test results show that CES columns under 3-side heating have higher fire resistance than that under 4-side heating. Also, load ratio and load eccentricity have noticeable influence on the fire resistance of CES columns. In addition, spalling of concrete decreases the fire resistance of CES columns.

Abstract: The influencing factors of landfill leachate are analyzed. This paper introduced the common computational methods for quantity of leachate generation, and put forward some measures and methods to control quantity of leachate generation.

Abstract: In this paper, the caculating model of pile foundation accounting for bearing capacity of soil under pile cap is established. The influnces of pile spacing on load-sharing ratio, settlement and pile top force has been analyed. The result shows that load-share ratio of soil under pile cap and the settlement of pile foundation increase with the pile spacing; and the force of each pile tends to uniform with the pile spacing increasing gradually.

Abstract: DEA (Data Envelopment Analysis), Charnes has been published since 1978, due to the method of the correct value of properties in recent years have taken full advantage in the corporate performance assessment. In this study, each road maintenance units in Taiwan is to be a Decision Making Unit, the last two years of each DMU manpower, equipment number, maintenance expenses, etc., as input data, and score above the level units as output data, to analyze the performance of road maintenance authority, then proposed suggestions for improvement to the less efficient units, it can be a reference for follow-up work to enhance the efficiency of the road to the maintenance unit.

Abstract: Rainfall is a significant factor leading to failure of tailings dams. The impact of rainfall on the instability of dams is mainly reflected in the variation of negative pore-water pressure (i.e. matric suction) during rainfall infiltration. However, there is a lack of study on the effects of rainfall on suction in tailings dams. In this study, the response of suction to artificial heavy rainfalls in a tailings dam was investigated. The effects of rainfall intensity and surface vegetation conditions on the response of suction were studied. It is found that suctions at a certain depth in the tailing dam were kept constant until the wetting front reached this depth. Once suctions were altered, the values dropped rapidly. The magnitude of suction change generally decreased with depth. Rainfall infiltration mainly occurred above the depth of 40 to 80 cm when subjected to rainstorm and heavy rainstorms. Larger rainfall intensity leads to shorter response time and to larger depth affected by rainfall, implying that the tailings dam is more susceptible to shallow landslide failure under larger rainfall intensity. The existing vegetation increases infiltrability significantly and then produces an adverse effect on the stability of the tailings dam. On the other hand, it is observed that the presence of vegetation greatly prevented surface erodibility and then decreases the possibility of debris flow.

Abstract: The foundation reinforcement method was discussed based on an actual engineering example. The paper analyzes the cause of the fissures happened on a highway existing culvert. The combined reinforcement method with root piles composite foundation and static pressure grouting was adopted for the area that settles obviously. The method of design and construction about the composite foundation was introduced .The practice has proved that good reinforcement effect can be obtained when applying appropriate composite foundation for foundation treatment．