Applied Mechanics and Materials Vols. 351-352

Abstract: This article offers a new style of pipe pilestinging prestressed concrete pipe pile on the basis of the prestressed concrete pipe pile. The document introduces the construction technology. At first, reserve holes in pile in advance, then press concrete blocks into the soil throughout the holes by workers or construction equipments. The author also carried on the finite element analysis, established a common prestressed concrete pipe pile model PZ and a stinging prestressed concrete pipe pile model CZ. The results showed the value of bearing capacity of CZ increased by 9 %comparing with PZ.

Abstract: To measure and determine the friction coefficients of steel wires accurately is one of the prerequisite for analysing the local bending stresses in staycables. Three test schemes to simulate the real working state of the steel wire, the test value and its variation trend shows that the friction coefficient of high-strength steel wires decreases with the pressure increase, and then becomes stable when the positive pressure is too large.

Abstract: This paper deals with a modeling of the composite timber-concrete ceiling structure. In the analysis of the composite structure, there is the slip using the contact elements and volume finite elements considered. Numerical modeling is complemented by an analytical calculation. This article aims to determine the stiffness of a particular type of glued strip. Totally eight models of the composite timber-concrete structure have been studied.

Abstract: A new type of wall-beam was put forward, of which the upper wall is replaced by recycled aggregate concrete whose coarse aggregate is made of the waste brick. Three recycled aggregate concrete wall-walls and three ordinary brick wall-beams were tested, and then the bearing capacity, stress-strain relationship, cracking load and failure mode were analyzed. The results show that: the structural integrity of recycled aggregate concrete wall-beam is better than ordinary brick wall-beam, and the increase of the depth of joist can improve the mechanical behavior of wall-beam structure under the condition of same depth-span ratio.

Abstract: A total of 18 cold-formed lipped channel columns with web stiffener were analyzed by using the finite element program of ANSYS. Varying length and axial force eccentricity were concerned to observe the buckling modes, load carrying capacities and deformability of the channel section columns.All the results can be the reference for later experimental study.

Abstract: At present, frustum tower is widely used in the large wind turbine on the international wind electric market, which is a typical high drumstick and dumbbell type high-rise structure, whose mechanical characteristics and design methods have some particularity. In this paper, using the finite element program SAP2000, the primary selection tower was carried on the static strength and stiffness analyses, some control indexes which affect the tower design were studied. Based on the FEM analysis results, combining with a great deal of model calculations, this kind of tower were optimized. Research results show that the material utilization rate of wind turbine tower is low, and that the top displacement and stiffness of the tower is the controlling factors of design. Based on the optimization results, a new tower with straight lower part and frustum upper part is proposed, which can increase stiffness of tower, improve the material utilization, and reduce the overall steel amount of tower.

Abstract: One scale model of 1.5MW wind turbine frustum tower in Baiyun Obo was carried on pseudo-static test. The failure mechanism and characteristics, stress changes and distribution laws, hysteresis performance and ultimate bearing capacity were studied. Test results show that the wind turbine tower belong to the sudden extreme point instability failure; the buckling bearing capacity is as the ultimate bearing capacity of tower. The maximum stresses of tower mainly distribute at the variable wall thickness section and bottom, while other parts basically dont yield. This indicate that the material utilization of this kind of tower structure remains relatively low, structural design has yet to be improved, at the same time recommends that reasonable strengthen measures should be taken at the weakest part of tower. The P-Δ hysteretic curve of tower shows anti-"S" shape, the overall strength and stiffness degenerate more rapidly, which indicates that the plastic deformation and energy dissipation capacity of frustum tower is poor. The test conclusions could reflect the stress condition of prototype tower and provide references for design.

Abstract: Static tests were conducted on a two-story mobile building under wind loads, and the building is composed of two box units of steel frame structures. The mechanical behavior and the deformation performance of the structures were investigated. Based on the principle of static equivalent, the horizontal loads to load points of the top of the columns were imposed to simulate the wind loads. The displacement values and relative shifting values of the frame structures were obtained. The tests results show that the horizontal deflections of the mobile buildings are greatly affected by the relative shifting of the separate box units. And the conclusion also applies to the container buildings.

Abstract: With wind tunnel tests, simultaneous pressure measurements are made on 4 cylindrical roof models with different rise-span ratios and roof inclinations. Effects of these geometrical factors on wind pressure characteristics of the roofs are investigated, including mean pressure coefficients, RMS pressure coefficients, skewness, kurtosis, and probability distributions of wind pressure. Results show that the mean vertical wind force coefficient of high rise-span ratio roof is larger than that of the low rise-span ration roof; the mean pressure coefficient distribution of the low rise-span ratio roof is similar to that of RMS pressure coefficients and the skewness (or the kurtosis); the vortex center line occurs at the windward edge for the low rise-span ratio roof with inclination 0°, which occurs at the roof apex for the high rise-span ratio roof. The roof inclination has more effects on the low rise-span ratio roof, the vortex moves from the windward edge to the apex for the roof with inclination 7.2°when the wind flows from the low eave to the high eave. The distribution of the skewness is strongly correlative to that of the kurtosis. The probability distributions of the roof edges and corners deviate obviously from the Guass distribution. If this point is ignored, the peak suction pressure will be underestimated.

Abstract: Elastic buckling of stiffened plate with local imperfections were presented in this paper. As its difficult to analysis buckling character of the stiffened plate with local imperfections by using elastic plate theory, this paper used finite element method (FEM) to model 30 different cases of local imperfections in stiffened plate, and analysed how the size, depth and direction of local imperfections affect the critical buckling coefficient of the stiffened plate. Results shown that, the size, depth and direction of local imperfections are have significant impact to the buckling behavior of stiffened plate, the largest decrease of critical buckling coefficient due to the local imperfection reaches 30% in this paper, and the critical buckling coefficient of stiffened plate with smaller stiffness ratio is more susceptible to the local imperfections.