Advanced Materials Research Vols. 163-167

Abstract: There is high requirement to the foundation of the raceway of container gantry crane. However, the marine soft soil is distributed extensively at Dalian ports. In the paper, the settlement and bearing capacity of natural and composite foundation of raceway of container gantry crane under design load is analyzed by finite element method on the basis of geological data, foundation treatment. The relationship of different deformation modulus and foundation bearing capacity is obtained by considering the strength of foundation and the requirement of settlement. The settlement and the inclination value of two sides of container gantry crane which is less than the permitting value of laws under consolidated ground and corresponding load condition is obtained. The corresponding deformation modulus of consolidated ground is obtained under different load condition. The boundary of basis is easy to failure, the treatment range extension of foundation should be considered.

Abstract: This paper examines the effectiveness of the Active Tuned Liquid Column Gas Damper (ATLCGD) when equipped on the plan-asymmetric structures subjected to earthquake excitation. The active behaviour is obtained by adjusting the pressure at the end of the liquid column using a pressurised reservoir. The classical linear quadratic regulator (LQR) control strategy is applied to determine optimal control force of the ATLCGDs. A case study of a four-storey asymmetric structure is conducted to illustate excellent control efficacy of the proposed active TLCGD control system.

Abstract: Local scouring around the bridge pier occurs because of flow separation and the development of several vortexes around the pier. Such scour holes can cause a weakness in the bridge which may see cracks occurring on the box girders, especially during flooding. This paper presents a design scheme in which a pile underpinning technique has been adopted for such cases during research into defects in bridges. Furthermore, the finite element model has been established to evaluate the bearing capacity of the bridge before and after adopting this new measure. A large quantity of calculation data indicate that the application of the proposed method performs appropriately and plays an important role in raising the bearing capacity of bridge. The specific program bringing this into effect correctly in a renovation project is illustrated.

Abstract: The hysteric-friction isolation system with elastic-plastic displacement-constraint device is put forward. The action mechanism and restoring force model of the elastic-plastic displacement-constraint device are analyzed. The nonlinear seismic responses of structures supported on Hysteric-friction isolation system with elastic-plastic displacement-constraint device under main shock and aftershock are researched. The results indicate: the displacement-constraint device not only can ensure the upper structure safety, but also can effectively limit the displacement of the isolation layer, meanwhile can supply secondary protection under strong aftershock. The structure of the device is simply, which is convenient for production and installation. Meanwhile because the device is cheap, it can be widely used in isolation building.

Abstract: In the Ms8.0 Wenchuan earthquake on 12th May 2008, a large number of primary and secondary school buildings were seriously damaged. Therefore, considerable attentions have been paid to earthquake resistance capacity of school facilities and some relevant national codes in China have been updated after earthquake. Recently, many approaches to seismic retrofit of school buildings have been proposed and applied. The focus of this paper is on application of energy dissipation technology to C-category frame structure of school buildings retrofitting, with the objective of increasing one grade of precautionary intensity, while the C-category buildings are designed in conformity with China’s code for seismic design of buildings (GB 50011-2001). Since the seismic precautionary classification of school buildings has been changed from standard precautionary category to major precautionary category, the structural ductility requirements are stricter with the increase of seismic precautionary intensity. Thus, this paper presents the retrofitting difficulties in C-category frame structure of school buildings for the restriction of ductility requirements, and also explores how to apply energy dissipation technology to seismic retrofit of such buildings for achieving expected retrofitting objective and reducing heavy strengthening tasks. In the end, a retrofitting example of C-category frame structure of school building is cited to demonstrate the feasibility of energy-dissipating retrofit method. The analysis results indicate that energy dissipation technology can be well applied to C-category frame structure of school buildings retrofitting for increasing one grade of precautionary intensity.

Abstract: As excavation and precipitation involved in the foundation works will cause subsidence of the building foundation surrounding, grouting uplift technology is widely used to control settlement. In this paper, relied on rectification of one building, a three-dimensional finite difference model of grouting-soil-building interaction is established. Based on the method of imposed volumetric strain, the uplift process of grouting is simulated by expanding cell volume applied radial velocity to the grid nodes on the spherical slurry bubble. The variation regularity of surface deformation uplift, upper building deformation and internal forces on various stages of strata grouting are discussed and analyzed, and compared with the data on-site monitoring. The results show that the measured values and calculated values are in a good agreement. The method of applying the node speed to simulate non-uniform spherical expansion of multiple slurry bubble may predict the grouting uplifting preferably and provide a reference for design of grouting uplift and building rectification in the future.

Abstract: Due to heavier traffic loads, progressive structural age, and corrosion of steel reinforcement, there has been an increasing need to strengthen the pile foundation of concrete bridges. In this paper, the damages and deteriorations on a concrete bridge in Guangzhou City are described in details, which causes are discussed also. The rehabilitation method by prestressed cushion cap is proposed based on the finite element analysis. The rehabilitation scheme is verified by the result of calculation, and the practice of strengthening project proves that this method is technical feasibility, construction convenience and lower economic cost. The research results can be provided as a reference for the similar bridges.

Abstract: The study on the rehabilitation of RC members with stainless steel wire mesh and polymer mortar indicates that debonding failure of reinforced layer is one of the main failure models. The key of the successful rehabilitation is that how to ensure the bond performance between reinforced layer and concrete. The experimental studies on the debonding failure between reinforced layer and concrete are carried out, and the influencing factors and characteristics of the debonding failure are analyzed, and the bond-slip curves are tested. At the same time, the program, ANSYS, is used to found the finite element models to simulate the experimental studies. The results show that there is an effective length of reinforced layer, which is extremely remarkable to the bond strength, and the main factors include curing age, interface roughness, concrete and polymer mortar strength. Based on experimental test and numerical simulation, the debonding strength formulas and bond-slip relationship of reinforced layer are presented, which can used to analyze some structures.

Abstract: In this paper, the stress distribution of the orthotropic steel bridge deck in a suspend bridge under local wheel load is analyzed. Some retrofitted methods are introduced, two of which are studied. One is using the concrete paving layer (CPL), and the other is using the sandwich plate system (SPS) to strengthen the orthotropic steel bridge deck. Local finite element models are established by ANSYS; stress distribution of bridge deck is calculated under the designed vehicle load before and after the deck retrofitted by the CPL or the SPS, and the results are compared with each other. The analysis results indicate that, under wheel pressure load, the orthotropic steel deck appears stress concentration; after the deck was retrofitted no matter by the CPL or the SPS, all the stress peaks decrease obviously, and the fatigue resistance of the orthotropic steel deck increases, which indicate that the two methods are effective to retrofit the orthotropic steel bridge deck. Using the CPL method can lead to lower stress concentration than that of using the SPS method, but the concrete paving layer is easy to crack, so, high performance concrete with high tension strength is needed.

Abstract: Bored pile is one of the most widely used foundation forms in civil engineering. Relationship between pile quality and its’ bearing capacity is seldom been discussed. This paper introduces 8 bored piles in one storage tank project in Ningbo, of which 4 piles are done vertical load tests; the other four are done lateral load tests. Combined with their quality, the results reveal that when load is small, pile quality has much influence on pile bearing capacity. As soon as load is large enough to transfer to pile bottom, quality of concrete at pile bottom becomes the main factor that impacts pile vertical capacity, meanwhile pile horizontal bearing capacity mainly depends on pile length. Post-grouting is done to improve pile quality. It raises pile’s bearing capacity while reducing differential settlement at the same time.