Advanced Materials Research Vols. 639-640

Abstract: The equilibrium equations of elastic support circular arches considering geometrical imperfections are deduced from variation principle. And the relations between external load, radial displacement and axial forces are determined; also the equilibrium conditions of snap-through buckling and bifurcation buckling in circular arch are ascertained respectively. Further, influences of geometrical imperfections and elastic supports on in-plane stability are analysis with analytical and finite element (FE) method. And the compared results display that the two methods coincide with each other very well for smaller opening angle in circular arches. The geometrical imperfections have only certain effects on the buckling path, while the elastic support rigidity play a significant role in both the path and critical load of snap-through buckling.

Abstract: The prestressed concrete box-girder with corrugated steel webs is a new type of steel-concrete composite structure. It has some advantages comparing with traditional prestressed concrete structure. Shear connector is a decisive component with which steel and concrete can work together in steel-concrete composite structure. In this paper, the most commonly used forms of shear connector in prestressed concrete composite girder with corrugated steel webs are introduced. The method of design and calculation of shear connector is described. Furthermore, the engineering design case of shear connector in the 4th Nanjing Yangtze River Bridge North Terminal Chuhe Bridge is presented. The method can be taken as a reference to the design of shear connector in the same kind bridge.

Abstract: The beam-column joints play a key role in composite steel and concrete structures. In order to ensure a safe design of a new building and obtain optimum design, an experimental program consisting of the tests of three connections with different connection details under low-cyclic reversed loading, A series of mechanical performance such as the stress-strain relationship of steel beam web, beam flange, connecting plate, bracket web, bracket flange, distributing steel, concealed column in node core area are all analyzed, the results show that in the loading process, steel beam flange and web ,bracket flange produced yield deformation, but the bracket web, distributing steel, concealed column didn’t yield, so the steel beam flange and web, bracket flange must be strengthened in the design. The test results also show that the bracket can be regarded as canlitecver model in practical engineering.

Abstract: Based on the data of the strength tests of concrete performed brick masonry，the basic strength formulas of concrete performed brick masonry are obtained. Through regressive analysis, it will be coherent to the compressive strength of concrete performed brick masonry to introduce the adjustment coefficient of mortar contrast to the Code for Design of Masonry Structures of China. The shear strength, bending strength along straight joint and bending strength along straight joint are uniform with the Code for Design of Masonry Structures of China.

Abstract: To investigate the flexural bearing capacity in negative moment region of composite beams，we examined different ends constraint components. The modeling of the beam ends connected framework has been done by the finite element software ANSYS. The concrete thickness, slab reinforcement ratio and different component at the edge of the composite framework in the negative moment region are taken into account. The performance during the process of deformation and failure are got by nonlinear analysis. The flexural bearing capacity was reported, with the negative moment region of the composite frame beam, it revealed great differences when the beams are different component. Simulation results show that the concrete thickness take the biggest influence on bearing capacity. The results showed the behaviors of the composite frame beams are different with positive moment region, and calculation based on current code for design of steel structure (GB50017-2003) would be a big deviation.

Abstract: The dynamic control equations are derived for the mechanical model with two degrees of freedom that the soften spring is considered in the dynamic vibration absorber. In order to facilitate the computation to the equations, through the integral of the dynamic control equations which became a four order ordinary differential equation. The amplitude frequency response curves of the primary structure excited by a harmonic force were drawn with harmonic balance method, the influence of the dynamic characteristics of primary structure about this kind of nonlinear dynamic vibration absorber was discussed.

Abstract: Differential Transform Method (DTM) is a new semi-analytical, semi-numerical algorithm, which transforms differential equations to the form of Taylor series. The method derives an approximate numerical solution based on Taylor series expansion, which is a analytical solution built on polynomial form. Traditional Taylor series method is used for symbolic computation, while the Differential Transform Method obtained the solution of the polynomials through itineration calculations. Applying DTM to buckling problems, the critical length of a bar at clamped-free boundary is studied. The computational results are compared with analytical solutions and shown excellent agreement between those two algorithms. The method adds a new tool for computational engineering mechanics.

Abstract: China is a large agricultural nation where most of the population and national economy is concentrated in rural areas. At the meantime, our country is a seismic country where earthquakes frequently take place. The earthquake disaster of Wenchuan in 2008 seemed that it always cost a great damage in rural areas. According to the present situation, a new type of seismic practical technology called steel-asphalt composite isolation lay is put forward with the characteristics of economic, simple and reliable. In order to test the effect of the new isolation layer, we have built a new house in use of the isolation layer nearby the rural areas in Changsha, beside the shaking table experiment in laboratory. The practical engineering in masonry structure has three floors and a basement. After the structure of the house had been finished, we tested the isolation effectiveness of the house. The results showed that the isolation layer can decay the acceleration about 40% and the isolation effectiveness is very well. Therefore, the seismic grade of the super structure can be reduced. So we took use of the High Performance Ferrocement Laminate as the ring beam and constructional column instead of the reinforced concrete. The cost of the upper structure can be reduced. And the money can be taken used on the building of the isolation layer. Therefore the whole cost of the structure didn’t increased.

Abstract: The shear-resistant behavior of reinforced concrete (RC) columns subjected to axial velocity pulse-like ground motions was studied. Single RC columns with the constant vertical and horizontal fundamental period were used to investigate the influences of fault-distance of earthquake records, vertical to horizontal acceleration spectral ratio of earthquake records, initial axial load ratio and shear span ratio of RC column, on the shear-resistant behavior of RC columns. a suite of 18 strong ground motion records from Chi-chi earthquake divided into three fault-distance groups were taken as excitations to execute nonlinear dynamic time history analysis. The results demonstrated that axial velocity pulse-like earthquake action (fault-distance) had significant influences on the shear resistant-resistant of RC columns. Shear-resistant behavior (shear capacity/shear demand) increases with the increasing of fault-distance. Fault-distance and shear span ratio had a certain coupling influences on the shear-resistant behavior of RC columns.

Abstract: Vibration control of a 22 story RC frame-shear wall apartment building with large aspect ratio was studied in this paper. Three vibration control plan with mild steel dampers, viscous dampers and viscoelastic dampers were proposed to control structural dynamic responses under earthquake. The dynamic responses of the structure with the proposed control schemes under earthquake excitations were investigated and their vibration control effects were compared. The numerical analysis results show that structural dynamic responses under earthquake excitations can be decreased effectively using the proposed plan. The earthquake response with viscous dampers was smaller than that with mild steel dampers and viscoelastic dampers. The shear force, drift and the acceleration of the structure with viscous dampers were 20%-40% less than the structure without any dampers for the slender structure.