Advanced Materials Research Vols. 941-944

Abstract: Traditional experiment studies on bond behavior between concrete and steel bars (corroded steel bars, FRP bars) are based on concentric pullout specimens. However, the bond behavior of concentric pullout specimens is different from that of RC elements in many aspects. This paper proposed a new kind of beam specimens based on previous researches. Based on the new specimens, this paper investigated the effects of stirrups on the bond behavior between concrete and steel bars. The test results showed that the effects of stirrups on bond behavior were more apparent after bond failure.

Abstract: In the process of large-span tunnel excavation by arch cover method, how to ensure the safety of construction and to reduce the influence on the surroundings and environment has arising wide attention of scholars both domestic and abroad. But now it is still in the stage of experience as to the rock pressure and its instability failure, especially to the research on rock overload damage. Regarding the large-span tunnel rock failure mechanism of progressive collapse by arch cover method, large-diameter modeling test are adopted to do systematical research on the rock failure phenomena as load increase. Determine its ultimate failure state by increasing vertical load, then we can get its failure characteristics and instability criterion in different rock support section.

Abstract: In this paper, by the finite element analysis software-ABAQUS, nonlinear analysis models of steel concrete composite beams under vertical low-cycle repeated load were simulated. The influence of seismic performance parameters, such as degree of shear connection, the ratio of height to thickness of the web were studied, and these parameters’ appropriate range were advised. According to the finite element analysis and test results, formulas of positive and reverse stiffness degradation, a trilinear model for moment-curvature hysteretic performance of simply-supported steel concrete composite beam were proposed.

Abstract: Numerous concrete and reinforced concrete structures (industrial floors, petrol station or manoeuvring park pavements, elements of sewage system) are subjected to danger of permanent or periodical action of petroleum liquids that often causes the considerable reduction in concrete strength as well as decrease of bond between concrete and steel, which usually results in structure damages. The subject of the paper is estimation of influence of polymer dispersion additive (styrene-acrylic co-polymer and styrene-butadiene latex) onto durability of concrete subjected to action of different types of light liquids. The influence of polymer dispersion additive was confronted with the action of silica fume usually applied for sealing the structure of concrete. In the paper there are presented tests results for different types of light liquids onto such cement-polymer concrete properties as: strength, penetration depth of light liquids into material structure.

Abstract: The opposite-pull retaining wall, formed by the anchor of both sides opposite-pulling the cantilever retaining wall, is a new type of supporting structure. Comparing with traditional retaining wall, the bearing ratio changes remarkably which will influences the structure stress. In order to popularize and apply the type of retaining wall structure, indoor model is made with different magnitude prestress applied and different magnitude is applied on top of the retaining wall to simulate different filling height. Test shows that as the top load increases the proportion of load beared by anchor decreases while that beared by retaining wall increases and the proportion of load beared by the lower anchor increases gradually. And soil arch effect appears near the anchor. The retaining wall around the anchor need reinforcement treatment during the construction.

Abstract: Through modification of the rubber surface, the adhesive ability of rubber particles and cement based materials has increased, thus improving the mechanical properties of rubber concrete. Dosage of styrene butadiene latex was studied under the condition of 5% cement quality, the change regularity of different amount of rubber latex rubber modified concrete compressive, splitting, flexural strength and other mechanical properties. The test results prove that the latex rubber mixing can improve compressive, splitting and flexural strength of concrete.

Abstract: Micro-pile is mainly introduced in this paper the construction technology and its main connections with superstructure in building heightening and transformation. The bearing capacity of micro-pile should be calculated follow the traditional method of pile foundation,and it should be improved to distinguish the different soil conditions.

Abstract: Snowdrift patterns exhibit various forms according to the architectural shapes and models. As snowdrift patterns largely influence the snow loads that buildings have to withstand, a number of studies have been conducted. This study examines snowdrift patterns and how the amount of snow comes to rest depends on the shape of a roof (for flat and gable roofs) using a wind tunnel test. An analysis of snowdrift patterns and accumulation coefficients, which are representative of the depth of snow cover, for flat and gable roofs showed that accumulation coefficient decreases in accordance with increases in wind speed. The gable roof exhibited a slightly higher accumulation coefficient than the flat roof.

Abstract: The effect of steelmaking slag and fly ash as multi additives on permeability and mechanical properties of permeable concrete was investigated. The results show that multi binder with fly ash, steelmaking slag and cement has a significant impact on the permeability and compressive strength of permeable concrete specimen. When the co-doped admixture is added with fly ash (15 wt.% ) and steelmaking slag (10 wt.%), good mechanical properties and high permeability coefficient were obtained. Fly ash and steelmaking slag has a micro-aggregate filling effect on the concrete interface.

Abstract: The shear property of bonding interface between new and old concrete with bonding-in reinforcement was researched. The shear experiment was done to 6 groups with 18 specimens with 5 interface agent types of casting new concrete directly, painting neat cement, painting merchandise agent and with bonded-in reinforcement. The shear properties of bonding interface were analyzed, and the shear strengths were compared with each other. The experiment results show that the shear strength of the interface could be enhanced remarkably with bonded-in reinforcement. The practical calculation formula was proposed, considering the influence of interface roughness, agent and bonded-in reinforcement. In the end, the formula was validated by other experiment and could be used in the strengthening design for concrete structure.