Advanced Materials Research Vols. 671-674

Abstract: How to estimate initial cable pretension is one of key problems for mega steel frame and cable bracing structure. In this structure, pre-stressed cables work as components of lateral resistance and elastic supports for mega-beams. Based on these two roles, two principles about determination of initial pretension in them were presented. One is that the residual tension will be near to zero in the most unfavorable condition. The other is that the mega-beam deformation, not showing inverted-arch shape, meets Chinese code requirements in the normal service state. According to these two rules and superposition principle of structural deformation, the relationship between the mega-beam deformation and the cable force under vertical and horizontal loading were established. Further, the detailed calculating formulae and determination method about initial cable pretension were given. They are useful for preliminary design and qualitative analysis of mega steel frame and cable bracing structure.

Abstract: To investigate the influence of wire mesh type, wrapped way and stress of column on the behavior of RC square columns, the experiment including an unreinforced column and 7 strengthened columns with the high strength wire mesh mortar were tested. The results were shown that the strength and axial deformation of columns reinforced by high strength wire mesh mortar were enhanced. Finally, the calculation formula for ultimate bearing capacity of the reinforced columns was given based on the test results, which agreed with the tested results well.

Abstract: This article mainly analyzes characteristics on bearing capacity of wall consist of the straw composite board under vertical load, as well as bearing characteristics of various member under vertical load. Through the model test of 1:50 scale, it is obtained that cracking load, ultimate load and deformation of various elements of wall model in the process of test. The required data is provided that the bearing capacity formula under axial compression is to calculate straw concrete wall consist of composite board.

Abstract: 3 extended-end-plate joints of T-shaped concrete-filled rectangular composite tubular column with H-shaped beam were designed. The experimental research and ANSYS nonlinear finite element analysis on the earthquake resistance behaviors of the joints were conducted under low cyclic loading. The results indicate that the shapes of hysteresis curve of each specimen is full and presents spindle, all the specimens possess good energy dissipation capacity. The end-plate thickness and high-strength bolt diameter have a great influence on the bearing capacity of the joints. Increasing the thickness of end-plate and the diameter of high-strength bolt, the displacement ductility factors of the joints decrease slightly, but their ultimate bearing capacities obviously enhance. The stress distributions and the finite element failure characteristics of the joints are basically consistent with the test phenomena, yield bearing capacity and ultimate bearing capacity of the finite element calculations can agree well with the experimental results.

Abstract: Small span arch steel structures on spring-settlement support and normal support were designed as research objects. 1kg, 2kg, 3kg and 5kg TNT group charges were detonated respectively on the center surface of backfill above the structure. Numerous data was obtained during these tests. The comparisons of measured parameters were done between the structure with spring-settlement support and normal support. The results indicate that, the structure with spring-settlement support can reduce the magnitude of internal force of the structure, decrease the dynamic effects on the structure significantly, and enhance the bearing capacity.

Abstract: Eight reinforced concrete beams (six externally reinforced and two contrast beams) were tested under primary or secondary load experiment. According to the test results, the existing specifications were applied to make calculations on short-term deflection which leaded to a large error. The secondary effect should be considered on calculating the deflection. Therefore, comparisons were made between the improved calculated value and test value on deflections of reinforced concrete beams strengthened by externally prestressed transverse tensioning method and they are in good agreement.

Abstract: FRP (Fiber reinforced polymer) is a two-way designed material from both macro and micro design. Former design was carried out according to the structural design, and the micro design is the material design on fiber volume ratio and the resin types. FRP is eminent in civil engineering because of its high strength to weight ratio, durability prolongation, high stiffness to weight ratio and its fatigue resistance behaviors. Right now, lots of applications were found in offshore engineering, hydraulic engineering and railway engineering. This article focused on both design and construction of the FRP reinforcement with concrete, and a case study was provided from the Nanjing city by CCEED (China Construction Eighth Engineering Division).

Abstract: The dynamic effects on a pre-stressed multi-story steel plane frame caused by sudden failure of a pre-stressed cable were investigated by general finite element software. The stiffness reduction method was adopted to simulate sudden cable rupture, which can induce dynamic response of the pre-stressed multi-story plane frame. The numerical results show that the recommended failure time should be less than 1/20 of the fundamental period of the remaining structure to consider dynamic effects more accurately. As the failure time decreases, the amplitudes of structural top lateral displacement and internal forces at the column ends all increase and they decay more slowly. The dynamic coefficients of bending moment and shear force are larger than that of axial force at the column ends. The farther the beam is from the failed cable, the faster the bending moment at the beam end decays, and the larger its dynamic coefficient is.

Abstract: This paper descries work carried out using ANSYS finite element techniques to evaluate the longitudinal residual stress distributions of the welded monosymmetric I-section in various web height-thickness ratios. From the analysis results, it is shown that, with the web height to thickness ratio increased, the peak values of residual tensile and compressive stress in flange decrease, and the peak residual tensile stress in web decrease too, but the peak residual compressive stress increase. Meanwhile, the distribution width of residual tensile stress in flange and the distribution width of residual compressive stress in web all present increasing trends. The magnitude of the maximum longitudinal residual tensile stresses in both the flange and web reach the yield stress fy, while the maximum residual compressive stress in wide and narrow flange is close to 0.4 fy and 0.3 fy respectively, and the peak value of compressive stress in web which closes to the wide flange and to the narrow flange is about 0.4fy and 0.3fy separately. With the change of height to thickness ratio of web, the distributive width of residual tensile stress in flange or web is about 0.3 times of flange width or web height.

Abstract: The many low rise roof structures are sensitive to the effects of fluctuating wind load. In engineering design for the structures, spatiotemporally varying wind loads on the low rise roofs are modeled as equivalent static wind loads. In this paper, the equivalent static load of the large span roofs is formulated in terms of either a weighted combination of modal inertial load components, and the resonant and background load components that was obtained by the POD (Proper Orthogonal Decomposition) and LRC (Load –Response -Correlation) techniques.