Advanced Materials Research Vols. 446-449

Abstract: With the rapid urban underground rail development, a considerable number of cities bridges face the impact of the MTR. The subway construction through the city bridges lead to a considerable degree of subsidence, deformation, cracks and even a partial collapse, severely affected the bridge function. As the Beijing Subway Line 10 passing through Xinxing Bridge for the study object，the author set up the health monitoring index system of the subway construction through the city bridge, and analyses the monitoring data and the impact for the processing of subway construction across the bridge.

Abstract: The majority of low-rise buildings are generally susceptible to wind damage in previous wind disaster, thus it is necessary to gain understanding of the characteristics of wind pressure for these types of building. Based on Wind Tunnel Test, the shape coefficients were studied with pressure measurement on gable roofs laying aside purlin of low-rise building roof in this paper. Three aspects were arerespectively discussed: the lows of shape coefficients and the shape coefficient value with specific wind angle on roofs of the houses completely closed, the house opened doors and windows and the house opened the hole on roof with different wind angle. The laws of shape coefficients were propounded for low-rise buildings with different positions of openings in contrast to load code. A detailed analysis of the experimental results shows that the shape coefficients will increase notably when there are the openings on metope and on roof, and the one is outward of roof, another is inward of roof. It is expected that the results should be valuable for the wind-resistance design of low-rise buildings.

Abstract: This paper analyzed the board of reliability on the elastic half space model. Considered the random of the larger variability parameters, such as foundation, board, load, the paper studied the reliability of this issue application of the response surface method of quadratic polynomials. This paper analyzed the influence of the random parameter variability on the reliability index β and failure probability, obtained some useful conclusions and had some engineering referencing.

Abstract: Along with the rapid economic development, the large power-generating wind energy conversion systems are increasing both in number and in size. Because of the high construction cost, the consequence of any structural failure, especially offshore where replacing a damaged member such as blade which weights tones, is pretty expensive. Consequently particular actions are required to the protection of these structures. Among these many strategies, continuously monitoring of the condition of the system which provides a predication long before the actual failure should be one of the most efficient ways. In the paper, the main problems and their corresponding surveillance schemes of the system including tower, foundation, blade and turbine nacelle are discussed.

Abstract: In this paper, the main influence factors of stress-concentrated coefficient Kt of cross shaped board-welded hollow spherical joints were analyzed by ANSYS. Through the combination of 17 specifications of welded hollow spheres and 40 specifications of cross shaped boards to form 122 kinds of cross shaped board–welded hollow spherical Joints, the paper mainly analyzed the influence on stress-concentrated coefficient Kt from some factors as follows: the length of the connection of the cross shaped boards (a)、the thickness of the cross shaped boards (t) , the outside diameter of the welded-hollow spheres (D) , the thickness of the spheres (δ), the weld size (hf) and the cross shaped boards which are cut or not. The analysis results showed: the SCF of the joints and some factors（a、t、D、δand hf） in all .A cross shaped board to cut its corner or not affected the stress distribution of the joints and the biggest difference between 12%; In the cross shaped boards connected the same length, when it rises to some degree, the influence of (δ) on ( Kt) is smaller; Along with the thickness of the large diameter welded hollow spheres increases, the slope of the stress-concentrated coefficient Kt increases; It is better to choose the hollow spheres with the small diameter or thick wall, and choose the cross shaped boards which shall be a little thinner, and also increase the connected length between the welded hollow spheres and the cross shaped boards; When the weld size is larger than or equal to 12 millimeters, SCF gently changes.

Abstract: Through a Community Model House of Chongqing and a finished residential tower for indoor formaldehyde detection, first arrive at the result that the model House location, direction, and physical environments and furniture set state influence on indoor formaldehyde concentration, and set Model House and production house for indoor formaldehyde density contrast,determine the accuracy of finished residential tower interior formaldehyde product standards by analysing the Model House status in all situations. For implementing individual acceptance of finished products ,it can greatly reduce duplication of effort by judging indoor environment and avoid unnecessary waste of resources.It also played a great role in the health, fast forward to finished housing industrialization in China.

Abstract: Considering the advantages of steel strands in mechanical properties, a new form of shape memory alloy (SMA) wire, SMA strands, is designed in this study. To compare the recovery properties of martensitic SMA strands and SMA wire, the recovery stress of which with different prestrains were tested by using a material testing machine with a temperature-controlled cabinet. In this experiment, the SMA strands and the SMA wire have the same composition and the same cross-sectional area. The experimental results show that the maximum recovery stresses of the SMA strands with different prestrain are almost the same, which illustrates that the prestrain has no much effect on the maximum recovery stress of the SMA strands. Moreover, the recovery stress curve in heating stage does not coincide with that in cooling stage. Furthermore, the residual recovery stress of the SMA strands in cooling stage is also smaller than that of the SMA wire. This demonstrates the SMA strands can recovery initial state better.

Abstract: Modal experiments are present to study dynamic behaviors of an external prestressed steel beam. The impact testing is introduced, when the input is fixed and FRFs are measured for multiple outs. Modal results indicate that the modal shape will increase when external prestressed load exists; the first order frequency of external prestressed load on the beam is higher than that of no load, but the amount of loads have little influence on the value of damping coefficients and the first order frequency; and there are denser frequencies with lager external prestressed load.

Abstract: The present work studies the fatigue strength of carbon nanotube-reinforced composites. The as-received muti-walled carbon nanotubes are separated and distributed in epoxy using a sonication method. The fatigue specimens are tested in a rotating beam testing machine. Effects of reinforcement and notch on the stress – life behavior are experimentally characterized.

Abstract: This paper presents a study on reinforcement of timber columns with longitudinal cracks strengthened by CFRP sheets under eccentric compression. An experimental program using special eccentric compression hinged-support was proposed to identify the failure modes and to investigate the recovery in load carrying capacity. Different combinations of eccentric distance and directions of the eccentric plane related to that of the crack plane were considered. This test can provide detailed experimental data for the application of CFRP strengthening on timber columns under eccentric compression which is an efficient method to maintain the original historical structure.