Advanced Materials Research Vols. 446-449

Abstract: Construction monitoring is a system, especially for long-span pre-stressed concrete continuous rigid frame bridge. Based on the construction control of the right bridge Ju-ma River NO.3 Bridge, this paper has made comprehensive conclusion and detailed discussion in the aspects of construction control method, the basic process of construction control, and bridge construction control survey methods. The findings described herein will provide considerable reference for the construction control of other similar long-span bridges.

Abstract: When the tubular joint is under stress, the stressed conditions on the intersection line are rather complicated. This article proposes to establish a cylindrical coordinated system for the stress on a tubular joint with axial direction, radical direction and circumferential direction as directions of coordinate axis. The system resolves the stress on points of the line of intersection along those three directions and establishes a mechanical analysis model for the stress on the tubular joint based on that. Besides, with combination of conditions of fatigue cracks of tubular joint, effective tensile stress specific to I-shape cracks are put forward and relevant mechanical formula are deduced accordingly. By taking fatigue tests of tubular joints of CaoEJiang Bridge as examples, the article also works out the position of the maximum geometrical value of stress on the line of intersection of tubular joint with applications of mechanical models and computational formula presented in the paper and compares the position with the result of test to explain the result of test.

Abstract: This paper presents the large deflection analysis of 3D steel frame using the Finite Particle Method (FPM). The FPM based on the vector mechanics discretizes the analyzed domain with finite particles whose motions are described by Newton’s second law. Instead of imposing a global equilibrium of the entire continuous system, FPM enforces equilibrium on each particle. One of the features of this approach is that no iterations to follow nonlinear laws are necessary, and no global matrices are formed or solved in this method. This paper provides the fundamentals of the FPM, including the structural discretization and particle motion equation. Then internal force formulations of 3D beam element are derived using the fictitious motion method. Two typical numerical examples are given to show the capability of the FPM in the large deflection analysis of 3D steel frame.

Abstract: GZO transparent conductive thin films were deposited by the direct current magnetron sputtering method from a ZnO target doped with Ga2O3 of 3wt% on glass slide substrates under high pressure of argon. The effect of substrate temperature on the GZO film’s morphology, optical and electrical properties is investigated by using scanning electron microscopy (SEM), UV spectrophotometer, four point probe and Spectroscopic Ellipsometer. The results showed that GZO thin films with high quality could be fabricated under the high pressure of argon.When substrate temperature is 250°C or below, surface morphology of thin films can be significantly improved.With the increase of substrate temperature, the crystal grain become larger, the crystal boundaries narrow and become clear, and reach a best case at 250°C. At the same time, the resistivity of GZO thin films decrease and reach the minimum which is 1.099×10-3 Ω•cm at 300°C while the average transmittance increase to 90%. Consequently, the properties of morphology began to get worse with the increase of temperature above 300°C.

Abstract: Regular anti-collapse analyses with dynamic factors to adjust static results are often not accurate enough. To solve this problem, theory of additional dynamic effects after members' failure (known as F-ADE) is discussed in this presented work with a study of two important parameters to reveal its mechanism. Theory of F-ADE explains why and how the results of regular anti-collapse analyses go inaccurate. Several safety measures for structure design are proposed based on the mechanism of F-ADE. Further researches are expected.

Abstract: Tests for compressive strength and splitting tensile strength were performed on the concrete reinforced by Polypropylene Fiber of two diameters and of three fiber contents respectively and the whole loading process was monitored by acoustic emission (AE) technique. The test results showed that compressive strengths of Polypropylene Fiber Reinforced Concrete (PFRC) changed slightly with the increasing of fiber content but that splitting strengths changed more. The change rule of splitting strengths with fiber content was related to Fiber diameter which would determine a certain average fiber distance in concrete. There existed a bound value of average fiber distance, which was the most favorable to the splitting strength. Nine AE parameters of specimens received from their splitting tests always showed maximum or minimum at a fiber content of 0.6 kg/m3, which meant that these parameters would be helpful to the further research for the action mechanism of fiber in concrete.

Abstract: The main structure of Shenzhen Baoan International Airport T3 Terminal uses reinforced concrete frame and the steel roof is free-form surface. The main concrete structure which is about 1038m from north to south, and 588m from East to west, is currently one of the largest Terminal in China. Because the Concourse is very long, the temperature force is relatively large when the bearing is hinged. In order to release the force, the spring bearings are set up along the length to Concourse. However, the displacement increases under earthquake because of the reduction of the stiffness .The speed-related viscous dampers are placed near the strengthened truss for limiting the seismic displacement. However, the damper parameters can be obtained by computing several times in practical engineering .It needs a long period to select the damper parameters especially for complex structures. So this paper takes Shenzhen Baoan International Airport T3 Terminal Cross Concourse as the research object, use the viscous damping theory, determine the additional damping ratio from the perspective of response spectra and the nonlinear damping parameters from the energy point, find a reasonable, fast method to set the damping parameters.

Abstract: This paper compares three standards of FRP strengthened concrete columns published by ACI committee, Concrete Society and China respectively. A test is designed according to the comparison. A total of five columns were cast and tested. The analysis of the load bearing capacity and ductility of the test result indicates that wrapping hoop GFRP can enhance load bearing capacity slightly and the ductility greatly, wrapping axial GFRP can enhance load bearing capacity greatly but the failure of column is brittle, wrapping axial GFRP over-wrapped with hoop GFRP can both enhance load bearing capacity and the ductility.

Abstract: The effective length of concrete filled steel tubular (CFST) frame columns is a key parameter to determine its ultimate strength for engineering design. There was no special design code, so engineers usually got the values according with specification for steel structure. This may cause error in some degree. Based on liner and non-linear buckling analysis respectively, the overall stability of a typical planar composite frame with CFST columns and steel beams was performed in this paper. By comparing the results of finite element method with current approach, some primary conclusions were given to refer for engineering practice on the composite frames.

Abstract: Soil Pressure in the chamber is one of the important construction parameters. It is very important to set up reasonable soil Pressure in the chamber for controlling the ground settlement, promoting the peed of drift and lowering the cost of drifting. Take some subway tunnel for example, and carry out the 3D finite element simulation. In order to investigate the influence on ground settlement from soil pressure in the chamber, take 15% of the progressive increase in earth pressure to simulate over-balance conditions and also take 15% of the progressive decrease in earth pressure to simulate under-balance conditions. The results indicated that while the soil pressure achieves equilibrium, the swell and the settlement are all small. While over-equilibrium, the swell increases, on the contrary, the settlement increases while under-equilibrium. So, a good control over the soil pressure is one of the most effective therapies for decreasing the ground settlement.