Applied Mechanics and Materials Vol. 590

Abstract: The flexural load-bearing performance prototype test has been made on the precast thin-wall steel and spun concrete composite pile with a diameter of 1000 mm (TSC pile). The load deflection curve and pile deflection curve at each loading step have been obtained. The bending test results show that the deformation of large diameter TSC pile experienced elastic, elastic-plastic and plastic three phases under the load of bending moment, the damage of pile was caused by the tension stress of steel in tension zone exceeded the yield strength, which belongs to the ductile damage. As for the TSC pile ultimate flexural bearing capacity, the measured value agreed with the theoretical calculation value, which shows that the existing thin-wall centrifugal concrete filled steel tube structure ultimate flexural bearing capacity calculation theory and method is suitable for large diameter TSC pile. Preface Precast Thin-wall Steel and spun Concrete composite Pile (TSC pile) is in the use of type Q235B or Q345B plate (strip) pouring of concrete filled steel tube made of crimping forming and welding, the centrifugal casting^[1]. The compressive strength of concrete is not less than 80MPa, with a new pile products bear large vertical load and horizontal load. Concrete pile has the characteristics of high compressive strength, flexural capacity is weak; While the flexural capacity of steel pipe pile is strong, has good plasticity, But easy buckling occurs when the axial compression, loss of compression capability. TSC pile is a steel - concrete composite structure between steel pile and centrifugal concrete pipe pile, not only can give full play to the advantages of the both, can also overcome the shortcomings of its own when used alone^[2]: With the inner wall of the concrete pipe, the outer pipe can enhance its stability ;and the inner concrete pipe with steel " confining effect", by the uniaxial stress state into three dimensional stress state, which greatly improves the compressive strength, With high anti-hammering capability, high penetration, pile sinking speed, good durability, pile quality, materials and low cost^[3]. The TSC pile has been successfully applied to industry, electric power, transportation and other areas, commonly used in port engineering pile type of larger diameter, and by the wind, wave and other horizontal load, to put forward higher requirements of flexural performance of pile body. Therefore it is necessary to study the flexural behavior of large diameter pile TSC. Model test is usually the most useful method to study the pile loading behavior^{[4, 5]}.In this paper, the diameter 1000mm of TSC pile bending prototype test has been conducted, and the test is a research on the large diameter pile in TSC subjected to pure bending bearing capacity. Experimental Study of Pure Bending of TSC Pile

Abstract: A two-run genetic programming (GP) is proposed to estimate the slump flow of high-performance concrete (HPC) using several significant concrete ingredients in this study. GP optimizes functions and their associated coefficients simultaneously and is suitable to automatically discover relationships between nonlinear systems. Basic-GP usually suffers from premature convergence, which cannot acquire satisfying solutions and show satisfied performance only on low dimensional problems. Therefore it was improved by an automatically incremental procedure to improve the search ability and avoid local optimum. The results demonstrated that two-run GP generates an accurate formula through and has 7.5 % improvement on root mean squared error (RMSE) for predicting the slump flow of HPC than Basic-GP.

Abstract: In this paper, the FEM software ABAQUS is used to analysis the pile-soil load share ratios, load share value of pile side friction and tip resistance for three bases, including natural raft foundation, conventional piled raft foundation and two-phase varying stiffness piled raft foundation. Furthermore, the deformation and settlement of deformation-coordinating device are studied as well. Based on the research of the working characteristic of piles and soil, it highlights the good working mechanism of two-phase varying stiffness piled raft foundation. The analysis results show that two-phase varying stiffness piled raft foundation, with obvious two phase stress characteristics, has a working principle between natural raft foundation and conventional piled raft foundation, fully making use of the bearing capacity of foundation soil, effectively improving the joint bearing capacity of piles and soil.

Abstract: The paper deals with the problems of the actual behaviour, failure mechanism and load-carrying capacity of the special bolt connection developed and intended for the assembly joints of the truss main girders chords of perspective railway steel temporary bridges. Within the framework of this problem solution, several types of structural details of assembly joints have been considered as the conceptual structural design. Based on the preliminary evaluation of advantages or disadvantages of these ones, in principle two basic structural configurations – so-called “tooth” and “splice plate” connections have been selected for the subsequent detailed investigation. This investigation is mainly based on the experimental verification of the actual behaviour, strain and failure mechanism and corresponding strength of the connection, and on its numerical modelling using FEM. This paper is focused only on the static loading tests results of the splice plate connections and their evaluation, which have already been finished. Simultaneously with the static tests, the fatigue loading tests are being realized, too, but they have not been finished so far, as well as the FEM numerical modelling.

Abstract: Precast thin-wall steel and spun concrete composite pile (TSC pile) is a new type of steel-concrete composite foundation pile whose performance is between steel pile and concrete pile. 3D numerical analysis model of TSC pile was established by FEM software in this paper. By compared with the laboratory bending test results, the model’s reliability was verified, and then the bearing capacity of TSC pile under horizontal load was calculated, moreover, influences of different cross section parameters (diameter, wall thickness, steel pipe thickness, pile’s length) on the horizontal bearing capacity of TSC pile were studied. The results show that: with the increase of pile’s outside diameter, wall thickness of steel pipe, wall thickness of concrete pipe and length of pile, the horizontal bearing capacity of TSC pile is increased. The outside diameter has a biggest impact on the horizontal bearing capacity of TSC pile, then pile’s length, steel pipe’s wall thickness, and the influences of concrete pipe’s wall thickness are the least.

Abstract: Field measurement and wind tunnel test of wind pressure on the surfaces of Wuhan International Stock Building were carried out in this paper, and the mean wind pressure coefficients, RMS wind pressure coefficients, wind pressure spectra as well as coherence functions were discussed. Meanwhile wind pressure distributions were analyzed. The results demonstrated that the distribution of the surface mean wind pressure coefficients obtained by wind tunnel test approximately agreed with that by field measurement, especially the mean wind pressure coefficients on the windward obtained by the wind tunnel test fitted those obtained by the field measurement well, while the RMS wind pressure coefficients of the wind tunnel results are smaller than those of field measurement, and the RMS wind pressure coefficients of some measure points of field measurement fluctuated greatly.

Abstract: By means of the numerical simulations, the scope of round-pier suction effects is researched in this paper. The research results show that the scope of round-pier suction effects increases logarithmically with flow’s velocity when pier’s diameter is fixed and the scope increases linearly with pier’s diameter when flow’s velocity does not vary.

Abstract: Along with the rapid development of urbanization, high density city is becoming more and more common. The dense buildings cause the high intensity of heat island effect, resulting in a large amount of energy consumption. In this research the relationship between the heat island effect and the building density has been studied by CFD software with other factors such as the building height and construction shape unchanged. Through a series of simulation and data analysis it is revealed that the effect of building density on the thermal conductivity is obvious. And the study put forward the measure to alleviate the effects of the thermal conductivity by controlling building density in a certain percentage under the premise of maintaining the land use efficiency. This result can provide scientific references for planners, architects, and government management decision makers.

Abstract: This paper presents a study on mechanical behaviors of three-truss plate-truss composite bridges. Both a model test and numerical finite element analysis (FEA) have been conducted. The results indicate that the deck load is allocated to each truss in twice. The first allocation is among the panel points of bottom chord elements (tie beams), and the other through lateral bracings. When the stiffness of each truss (arch) is approximate, the load allocated to middle truss is about two times more than that in edge truss in the first allocation, and the second allocation makes the load tend to approximate among 3 trusses. But the vertical bending moment of bottom chord elements and the axial force of spandrel hangers in middle truss are about twice as that in the edge truss, which should be paid attention to. The results will be useful as references for design of three-truss plate-truss composite bridges.

Abstract: The paper summarizes the results and evaluation of tests of the resistance of glass-fibre-concrete components used for footbridge deck cover subjected to wind loading actions. The main aims of this research was not only to verify the objective load-carrying capacity and serviceability of covering panels, but also to verify the use of glass-fibre-concrete and its properties, if applied for non-typical product. The tests also show the usage of the unique and effective method of the vacuum loading. The research has been elaborated based on the requirements of DAKO Brno Ltd. Company.