Advanced Materials Research Vols. 250-253

Abstract: It is necessary to study the dynamic responses of simple-continuous bridges under traveling vehicles action, which may benefit the improvement of their dynamic performances. According to “Standard Design Drawings” issued by Ministry of Communications of PRC, this paper considers the alterations of span length, decking width and sectional style and the differences of vehicle model and traveling speed, and calculates separately dynamic response of these structures with the “vehicle-bridge coupled vibration program”. As two key influential factors, vibration amplitude and acceleration are applied for the evaluation of structural dynamic performance. The results show that dynamic performance of simple-continuous cored slab bridge is deficiency in some degree.

Abstract: Laboratory triaxial tests of the soil reinforced with roots of Manilagrass were carried out in order to understand the stress-strain relationship. The change of shear strength indexes of the soil reinforced with roots of Manilagrass was investigated with the quantity of grassroots planted in the soil specimens. The results of laboratory triaxial tests show that the strength and capacity for resisting the deformation of soil reinforced with roots are better than those of unreinforced soil. And under the certain number of grassroots layers, the strength and capacity for resisting the deformation of soil reinforced with roots increase firstly and then reduce with the increasing of Manilagrass roots quantity. In other words, there is an optimal quantity of Manilagrass roots affecting the strength and capacity for resisting the deformation of soil reinforced with roots. The research results are important for understanding the mechanism and use of vegetation protection for slope.

Abstract: An experimental investigation on the uplift resistance of circular plate anchor in both loose and dense sand is performed. A test set-up and an in-house data acquisition system are developed to capture the force and displacement when anchor uplifting. Two distinct load-displacement responses for plate anchor in loose and dense sand are observed. The peak uplift resistance and dimensionless breakout factor are significantly influenced by the sand density as well as the embedment ratio. The increasing rate of peak uplift resistance with embedment ratio is limited by the critical embedment ratio beyond which a smaller increasing rate is occurred. The critical embedment ratios for this study are determined as 4 and 6 for plate anchor in loose and dense sand respectively.

Abstract: Numerical simulation of forming process is an issue that finds the solution of a series of unstable equilibrium states of cable-strut tensile structures with specific unstressed length. This is a long well unsolved theoretic question, which mostly lies in the couple of mechanism and elastic deformation. On the basis of the unstressed length, the theoretic parabolic curve element was adopted to simulate the cable with elastic tension and deformation. The vector of unbalance nodal force was subsequently formulated with the explicit branch-node matrix of topology in force-density method. And the dynamical relaxation method was used to solve the nonlinear equation to avoid the singular stiffness of equation. Numerical examples indicated that the proposed algorithm could calculate the unstable equilibrium state and simulate the forming process with the unstressed length of the active cables changing, and has some theoretical significance.

Abstract: The paper attempts to research the seismic behavior and mechanical mechanisms under repeated low-cycle loading of vertical connections in prefabricated reinforced concrete structures. Eighteen specimens were designed and tested, the test process and the mechanical mechanisms are studied, the seismic behavior of connections is analyzed, and the shear resistance formulas are proposed. The theoretical values based on proposed formulas are good agreement with test results. Under repeated loading, the shear resistance decreases, the connection ductility increases with connecting bar, but decreases with connection width. However, all the connections fail crisply with poor ductility. At sudden-cracking, the shear resistance increases with connecting bar, but changes nonlinearly with connection width. The resistance is composed of attributions of mechanism of diagonal-compressive column (MDCC) and mechanism of compressive friction action (MCFA). After sudden-cracking, the shear resistance is provided by weakened MDCC and dowel action of connecting bars (DACB). It increases with connecting bar and connection width.

Abstract: Chaancun landslide in Dalian city is located at the heartland of Dalian Xicheng International tourism business district which is the throat position of tourist attractions. Development of tourist attractions is influenced by Chaancun landslide. Formation and evolution of landslide have direct influence on estimation of landslide stability and prevention effect. Based on investigation and analysis, it is concluded that the current active landslide which is induced by human activity is a part of ancient landslide and it is important to note that the stability of both the current active landslide and the ancient landslide should be taken into account when the landslide is mitigated.

Abstract: In this paper, the stability of an explicit finite element method for wave motion of fluid-saturated porous media is studied based on the transfer matrix of calculating formula of the method. Transfer factor is defined to describe the stability of the method. The effect of time step, space interval and the value of permeability coefficient on stability is analyzed and practical stability criterion is presented. Research results show that with the increase of time step, the stability of the method will be deteriorated; with the increase of space interval, the stability of the method will be enhanced; with the increase of the value of permeability coefficient, the stability of the method will be enhanced.

Abstract: The design of bridges, in particular long spanned ones, is challenging in the sense that there are many complicated issues to be considered. Amidst the loads to be considered, like dead load, live load, wind load, and earthquake load, the wind load becomes the prime concern for the design of the bridges. The paper will introduce several newly evolved kinds of girder that were based on commonly known physic natural law by structural engineer. Further structural analysis and wind effect research should be done in the future to validate and decide the structural member dimensions. The main problem to be solved in strait crossing bridge is lateral wind load that will effect traffic safety as well as wind effect on structures (statically and dynamically) for long span bridge arrangement.

Abstract: Through studying the ground surface settlement monitoring for Fang Dou Shan highway tunnel Shallowly-buried Portal Part, this paper mainly discusses the deformation of surrounding rock range from ground surface to the arch crown of double-line tunnel, and analyses the effect on stability of surrounding rock during construction, with the whole process of excavation of highway tunnel being simulated by FLAC_3D. It can make great significance for construction safety and some other related parts.

Abstract: It may appear different diseases after years of operation on old bridges. In order to understand the actual working condition and the bearing capacity of the bridge, the static and dynamic tests are taken. It describes the principle and methods for the load test via taking Banlashan Arch Bridge for example in this paper. The stiffness, strength and dynamic characteristics of bridge structure are measured, and the maintenance and reinforcing schemes are proposed, according to the results of static and dynamic load tests. Through analyzing the tests, the data and information of bridge can be accumulated, and the mechanical characteristics of this kind of bridge are discussed.