Advanced Materials Research Vols. 255-260

Abstract: The theory of ultrasonic wave propagation characteristic in damaged concrete media was studied in this paper. Basing on the fundamentals of classical elastic dynamics and the model of damaged mechanics,the basic equations of elastic wave propagation in damaged media are established and the example analysis and a numerical calculation are displayed. The basic solutions of the equations is deducted. Because the damage exists in the construction, the concrete’s wave response comprised of the shape,the amplitude and the propagated time of the ultrasonic waves in the structure will change obviously. The transformation mentioned above is provided for further study of inverse analysis and nondestructive test of the structure.

Abstract: Based on multifractal theory and quantitative stereological method, nonuniform distribution of corrosion morphology in reinforcing steel bars were analyzed and corresponding multifractal spectrum was proposed in this study. The results showed that the corrosion morphology of reinforcing steel bars is multifractal. All the Δf values are greater than 0, which indicating the distribution of corrosion depends on the maximum subset of probability. The width of the multifractal spectrum (Δα) increases linearly as the corrosion mass loss ratio increases, which is a scientific index in characterizing the nonuniform corrosion degree of reinforcing steel bars.

Abstract: Considering softening temperatures of ordinary organic epoxy adhesives are too low, this study develops an inorganic adhesive which strength at 600°C is not lower than that at normal room temperature. Four reinforced concrete (RC) beams strengthened with CFRP sheets bonded with the inorganic adhesive are tested. The fire protection of the CFRP sheets is done using the thick-type fireproofing coatings for tunnel (TFCT) and steel structure (TFCSS) respectively. All specimens are tested in the furnace together. Specimens are exposed to fire for 1.5 hours in according to the ISO834 standard fire curve, and then naturally cooled for 1 hour. CFRP sheets at center point of bottom surface of beams are 300~470°C, and the corresponding displacements at mid-span are 1/1400~1/318 of the actual span. The CFRP sheets keep a good state and are tightly bonded on RC beams by the inorganic adhesive after fire. Temperature and deformation are analyzed by ABAQUS, and the simulation and measured results are in good agreement. The results indicate that, under the protection of fireproof coating, the CFRP sheets work well in cooperation with RC beams and slabs during fire. TFCSS is inferior to TFCT because the former is easier to drop and crack in fire. Analysis method of the finite element supplies a good way to temperature field and deformation calculation of structures in fire.

Abstract: Based on elastic mechanics, this article deduced the theoretical value of the maximum stress and maximum deflection of sheet structure which was applied on point supported glass curtain wall structure, and figure out the stress and deflection values by calculation example. After that by simulating the structure with the finite element software ANSYS we drew the cloud atlas of stress and deflection values which we analyzed and compared with the theoretical values. Finally we can work out the error between the theoretical values and simulate value and analysis it.

Abstract: Based on the stability theory, one roof structure with steel tubular arch-truss was taken as a research object. Linear buckling, geometric nonlinear stability and elastic-plastic nonlinear stability were investigated by applying ANSYS finite element software, and the relational curves of critical load-displacement were obtained. The analysis results show that material nonlinear makes obvious influence on the stability of the structure, material nonlinear and geometric nonlinear are taken into account at the same time can make a better understanding of the structural stability performance.

Abstract: The steel-plate-masonry composite structure is an innovative type of structural scheme popular in masonry structures with load-bearing walls removed for a large space. A total of 4 column specimens under static loading were tested to mainly study the failure modes, load-carrying capacity, and strain distribution in the critical cross-section. Results show that the composite columns started an initial failure from local buckling of the steel plate located between binding bolts; the main factors influencing load-carrying capacity included thickness of the steel plate, type of injected material, and initial column eccentricity; the working performance of the composite column with epoxy adhesive was better than that with cement grout; and re-distribution of compressive stress existed in the steel plates of the column. Also, the ratio of service load-carrying capacity to ultimate capacity of the steel-plate-masonry composite column is about 70%.

Abstract: Some secondary effect introduced by corrugated configuration of corrugated web was studied and formulas were proposed. The deduction for these formulas was resolved into two steps. Step I: to solve the behavior of whole corrugated web by considering it as an orthotropic plate; Step II: to solve the secondary effect according to the shape parameters of corrugation based on the result of Step I. Subsequently, a numerical experiment was designed to validate the analytical work with the help of finite element package ANSYS taking material nonlinearity into consideration. The results obtained from numerical and analytical methods show good agreement. It indicates that the formulas proposed in this paper are convenient and efficient. This research deals with this secondary effect for the first time; more studies are needed for the effect on local buckling of corrugated webs.

Abstract: Masonry retaining structure consists of precast concrete blocks, which has good looks and is in harmony with environment. Blocks with proper shape can be used in fluctuating belt of the reservoir area. The construction of masonry structure should conform to the following steps: first, excavate the foundation ditch, lay a cushion and arrange the controlling points, insuring the quality of the first layer of blocks; it would be better to choose inorganic coarse-grained soil as filler and to set a water filtering layer with a height more than 30cm behind the retaining wall; carry on the construction of earth filling behind the wall after the blocks are fixed as requested, and then fix the geotechnical grille when the height of earth filling reaches the elevation of the grille; put Geotechnical Fabric between permeable aggregate and the earth filling behind it to keep the two materials from mixing.

Abstract: A radial-circle-lined grid shell, its height changed step by step in the radial direction, is adopted in the roof steel structure of the Citizen Water Sports Center in Jiangyin, China. And the Spatial Crossing Tubular (SCT) joint is used for the connection of pipe members. Because the force transmission in the roof structure is different from the traditional truss structure, a lot of SCT joints are in a complicated loading state. The joint forces include axial forces and in/out-of-plane moments. To investigate the mechanical behavior and the load-bearing capacity of a typical SCT joint in such complicated loading condition, a full size model test of the typical SCT joint is conducted. The test process is summarized in the paper, together with the finite element calculation of the typical SCT joint in test conditions. By comparing the numerical results with the test results, several significant parameters of the connection are investigated, including the stiffness change of the joint, the transmission mechanism of forces, the ultimate load-bearing capacity and the failure mode of the joint. After investigation, several useful suggestions are proposed for the SCT joint design. They are also valuable for the design of similar SCT joints under complicated loading condition.

Abstract: In this paper, nonlinear finite element analysis on the steel frame with top-seat angle and double web-angles semi-rigid connection were carried out with ANSYS finite element software. In the analysis, connective, geometrical and material nonlinear were considered. Compare analysis results with experimental results, the influence of semi-rigid connection’s flexibility on steel frame was studied and some references to the design of steel frame with semi-rigid connection were supplied.