Advanced Materials Research Vol. 790

Abstract: Asphalt mixture is the common pavement materials in high-grade highway. The rutting is one of the main failure modes. Temperature and loading are the two main factors cause rutting of pavement.The rutting experiment were carried under same loading in different temperatures and in same temperature under different loading, the relation curves between rutting deformation and load duration were obtained. Comparing the rutting deformation and dynamic stability, the influence mechanism of temperature and loading to rutting is studied by the experimental method. The research results have theoretical guidance meaning in controling the rutting deformation of pavement materials and prolonging the service life of asphalt pavement.

Abstract: The post-fire behavior of a set of self-stress lightweight aggregate concrete filled steel tubular short columns (noted as SSLC-SSC) after exposure to fire was experimentally studied. Effect of the maximum value of fire response temperatures of the tubes and their geometric parameters on the strength and the other mechanical property of the specimens were especially discussed. The experimental results show that the specimens of SSLC-SSC have higher post-fire bearing capacity and better plastic deformation, there was no obvious descent segment in post-fire load-displacement curves of the most specimens subjected to fire load. It was concluded that the maximum response temperature of specimens has great effect on the post-fire bearing capacity of self-stress concrete-filled steel tubes subjected to fire load, and the value of self-stress corresponding to 10% of dosage of expansive agent has the greatest effect on post-fire bearing capacity of specimens of SSLC-SSC.

Abstract: The post-fire behavior of a set of steel fiber reinforced lightweight aggregate concrete filled steel tubular short columns (noted as SFLC-SSC) after exposure to fire was experimentally studied. Effect of the maximum value of fire response temperatures of the tubes and their geometric parameters on the strength and the other mechanical property of the specimens were especially discussed. The experimental results show that the specimens of SFLC-SSC have higher post-fire bearing capacity and better plastic deformation. It was concluded that the maximum response temperature of the specimens has great effect on the post-fire bearing capacity of steel fiber reinforced concrete-filled steel tubes subjected to fire load, and incorporation of 0.5% of volume of steel fiber is best for enhancing the axial compressive bearing capacity of the specimens of SFLC-SSC after exposure to fire.

Abstract: The post-fire axial compressive behavior of a set of steel fiber reinforced ceramsite concrete filled steel tubular short columns (noted as SFCC-SSC) was experimentally studied. Effect of the maximum value of fire response temperatures of the specimens and some parameters on the axial compression performance of the specimens was especially discussed. The results show that the surface of the steel tubes after fire presented dark red for 700°Cof furnace temperature and orange red for 900°C, and there was no obvious descending segment in post-fire load-displacement curves of the most specimens subjected to fire load. It was concluded that the axial bearing capacity of the specimens aftersuffering the furnace temperature of 900°C is much less than that of the specimens not subjected to fire load, and the volume of steel fiber of 0.5% of has the greatest effect on post-fire bearing capacity of specimens of SFCC-SSC.

Abstract: The post-fire axial compressive behavior of a set of self-stress lightweight aggregate concrete filled steel tubes (noted as SSLC-ST) after exposure to fire was studied. Effect of the fire temperatures of the specimens and some parameters on the axial compressive behavior of the specimens was especially discussed. The results show that the initial circumferential strain of surface of the steel tubes is much larger than the longitudinal strain of the steel tubes, and the specimens of SSLC-ST have higher post-fire axial compression bearing capacity and better plastic deformation. It was concluded that the local buckling and overall failure of the specimens take place in succession while the specimens are axially loaded, and there are a lot of slip lines with angle of 45^o on surface of the steel tubes.

Abstract: The numerical model of analysis of fire performance of a spatial pre-stressed steel structure with large span was established based on the software Marc. The thermal response and structural response of the pre-stressed steel structure was computed for some nodes of the structure in fire. The different fire scenes were considered for analysis of response temperature, displacements and stresses of the nodes of the pre-stressed steel structure.It is concluded that the temperature rise of the nodes of the structure is far behind that of air near the nodes, however they are quite close as the fire lasted for 3600s and almost the same after 7200s.The results show that the displacement of the node right above the inner cable is the maximum and the node above the outer cable has the smallest value of displacement and the maximum value is about two and half times as large as the minimum.The results show that the reason why the cables are out of work is that the equilibrium between the cables and the rods of the structure is lost, but not that the stress relaxation caused by thermal expansion make the cables out of work.

Abstract: Due to the increase of environment requirements, Fiber glass Reinforced Plastic (FRP) chimney liners are frequently used in coal-fired units. Wind and earthquake loads play an important role in the design of FRP chimney liners. Most of the engineering staff are still accustomed to accept single model, although, conjunctive model can reflect the effect of concrete cylinder on FRP liners and obtain more accurate internal forces of the liners under earthquake and wind loads. In this paper, a novel modified single model method is put forward to obtain accurate results.

Abstract: In order to apply original timber more effectively, the physical and mechanical properties of timber from camphor wood were tested. In total, seven square short timbers columns were fabricated, and then were reinforced by AFRP sheets with one, two and three layers in different reinforcing arrangements. The results showed that the columns with AFRP gave a great improvement in mechanical performance, and the loading carrying capacity, stiffness and ductility of the columns reinforced were also improved. The results also showed that the specimen with full wrapping of two layers of AFRP gave a higher deflection than the other ones. However, the load carrying capacity of the columns with AFRP arrangement decreased when the layers of AFRP sheets increased to three.

Abstract: Soil moisture and nitrate nitrogen were measured respectively in planting area and non-planting area in RANZHUANG experiment station from 2011 to 2012. The effect of human activity on soil moisture and nitrate nitrogen was analyzed. The results show that soil moisture content varies from 8.61% to 30.09% within 0~250cm depth and is tended to be stable below 250cm deep layer in non-planting area. The distribution of soil nitrate nitrogen is a single peak curve, the peak moves downward at a speed of 0.81cm/d in percolation of rainfall. Soil moisture varies form 21.23% to 41.67% within 0~400cm depth and is tended to be stable below 400cm deep layer in planting area. Nitrate nitrogen is mainly accumulated at 0~100cm deep soil layer in the wheat growth period. In the maize growth period, the distribution of nitrate nitrogen is double peak curve in 0~500cm soil profile. The upper peak occurs at 40~100cm soil layer, the peak of nitrate nitrogen content is between 26.7~54.6mg/kg; the lower emerges at 150~260cm soil profile, the value is between 36.7~106.36mg/kg. Deep percolation of the nitrate nitrogen is obvious due to unreasonable irrigation and fertilization. The nitrate nitrogen content accounts for 52.3% of the total nitrate nitrogen below the root zone soil, which is a potential contamination source of groundwater.

Abstract: Based on 76-storey Benchmark model, the optimization objective including displacement reduction index and acceleration reduction index is given under the effect of wind-induced vibration, by which kinds of dampers are optimally designed based on Genetic Algorithm. The optimization results show that the peak acceleration, peak displacement and peak storey drift of structure are remarkably reduced and kinetic energy and deformation energy are reduced significantly. It means optimized dampers have achieved good effect on wind-induced vibration control of the structure.