Advanced Materials Research Vols. 250-253

Abstract: Based on researchers of interaction theory and its application, mechanism of interaction among superstructure, base and foundation was analyzed and a design method was proposed. Combining with engineering construction cases, change law of internal force of superstructure in interaction system was researched through comparing results between interaction analyzing method and custom computation method. Some meaningful engineering design devices were concluded finally.

Abstract: The residual strength of reinforced concrete (RC) columns with ‘T’-shaped cross section after fire are decreased more quickly than those of RC columns with rectangular cross section for the former have thinner sectional thickness and larger surface area. The influence of several main parameters, such as exposure times, effective lengths, sectional dimensions, load eccentricity ratios, reinforcement ratios, load angles and longitudinal reinforcement yield strength on the residual strength of RC columns with ‘T’-shaped cross section after exposure to fire was investigated. A self-developed finite element program CAFIRE was applied in this study. 24300 hypothetical cases of columns after subjected to fire on all sides were selected for residual strength analysis. Different fire exposure times, effective lengths, cross section dimensions, load eccentricity ratios, reinforcement ratios, load angles and longitudinal reinforcement yield strength were considered in the analyses. Based on the simulation results, a practical method was proposed for calculating the residual strength of columns with ‘T’-shaped cross section after subjected to fire on all sides. The simulation results indicate that: (a) the residual strength of columns with ‘T’-shaped cross section decreases linearly with the increase of effective length, but it increases linearly with sectional width, ratio of sectional height to sectional width, and yield strength of longitudinal reinforcement strength; (b) the residual strength of ‘T’-shaped columns decreases markedly for a load eccentricity ratio in the range of 0.0 to 1.0, whereas it varies slightly for a load eccentricity ratio between 1.0 and 3.0.

Abstract: Many highways in China cross irrigation area of farm land. The water in rivers and ponds by two sides of roads can flush back into subgrade, and results in more water in subgrade soil, subgrade deformation and lowered capacity. With reconstruction and extension of Zhengzhou-Luohe segment in Jing–Zhu Highway as the research target, this study investigated the method for preventing underground water from entering subgrade. Through studying on capillarity water rise in typical soil of Zhengzhou–Luohe segment, we found out water rise pattern, predicted capillarity water rise and obtained the method for preventing capillarity water from rising into subgrade.

Abstract: Series of indoor tests were done to study the strength forming process of soft soil stabilized by cement. Dry cement was used to consolidate soft soil through modeling the field construction situation, and the stabilized soil samples in different curing days were studied by means of direct-shear test, grading analysis test and scanning electronic microscopy. So the parameters of shearing strength, granularmetric compostion and microstructure feature of treated soil in each curing stage were determined. Results shown that, at the early stage, there was a slow increase in the strength of cement-soil, and with the curing days increasing, the mechanical property, component and microstructure feature of samples were improved obviously.

Abstract: The limit equilibrium method for rigid body is used to analyze the stability of subgrade reservoir bank slope of granite stained. The sliding of subgrade reservoir bank slope reinforced by dynamic compaction along the interface will not be happened. In the most unfavorable conditions , the sliding surface will be formed inside the stained subgrade, which threatened to the safety operation of the expressway.

Abstract: The application of steel wire mesh and polymer mortar composites to the surface of reinforced concrete (RC) members as external reinforcement is a promising and recent new technique for strengthening and rehabilitating damaged concrete elements. This new technique has many advantages of resistance to fire, corrosion, ageing, and rapid construction speed. Test results indicated that the overall flexural behaviour of strengthened beam can be divided into three stages: precracking stage, cracking stage, and failure stage. Furthermore, a moment deflection model is developed based on the assumption of plane sections remains plane under load. The flexural behaviour of the strengthened specimens subjected to a four-point bending test was addressed by using transformed section approach. The suggested model was verified using the test data of 6 strengthened beams, and good agreement between experiment and prediction values is achieved.

Abstract: A simplified seismic calculation model of immersed tunnel is built up, which is applied to the seismic analysis of Hong Kong-Zhu Hai-Macao Bridge Project’s immersed tube tunnel. According to different spring stiffness of foundation and different spring stiffness of joint, the tunnel and joint’s force and deformation conditions are compared. The results show that: the influence of foundation spring stiffness is significant, for engineering design, the foundations of a more flexible approach should be preferred; contrary to joint force, the joint opening increases with the increase of joint stiffness, thus, flexible joint is better for project; the connection parts of floor and wall, the connection parts of roof and wall are the most disadvantageous position during the earthquake, so, these parts’ design strength should be strengthened and deformation control should be taken.

Abstract: In SSCC floor systems the concrete slab is composite with both steel stringers and crossbeams or only with stringers. The horizontal bending of the crossbeams of SSCC floor systems is not ignorable. From the deformation conforming condition, theoretical formulas for SSCC floor systems of double-railway bridges with two stringers are developed. The factors which influence the horizontal bending of crossbeams are discussed. Some conclusions are obtained. When the width of the SSCC floor system is given, the main factors which influence the horizontal bending of the crossbeams are the axial stress of the lower chords, the distance between the side stringers and the lower chords, and the continuous length of SSCC floor system. Increasing the horizontal inertia moment of crossbeams almost cannot reduce the horizontal bending stress of crossbeams. A slight horizontal rotation of the lower joints such as 10^-4 rad can release more than 3% crossbeam end horizontal bending moment.

Abstract: This paper investigates the behavior prediction of partially restrained (PR) connection with high strength steel by three-dimensional nonlinear finite-element (FE) analyses. The connection model is such that angle cleats are represented by radiuses corner section shell elements. The full interaction between angle and beam and/or column is simulated by contact element. The analysis results of the moment- rotation relationship and behaviour characteristic of the connection with high strength steel are compared and discussed. It is found that contact element and strength enhancement of the corner regions employed to the model are very important parameters for accurate prediction of PR connection behaviour with cold-formed high strength steel. The moment capacity prediction of top and seat angle connections based on EC3 has been shown to be reasonable compared with FE modeling. The proposed connection FE model is capable of predicting the ultimate load capacity and the plastic strain pattern with good accuracy. The model presented gives excellent results for increasing the connection capacity significantly due to employed higher strength steel section.

Abstract: Sanmashan side slope in the Three Gorges reservoir region is located in the center area of the Xincheng district, Fengjie county, China. Based on the analysis of hydrogeological structure of the studied area, one can conclude that a groundwater reservoir form near the side slope area after the impoundment of the Three Gorges Reservoir, which induces large groundwater pressure on the side slope. In particular, large hydrodynamic pressure will occur in the landslide mass under the condition of the reservoir water level descending significantly, which has bad effects on slope stability. Numerical simulation results show that the seepage force on landslide is 43 times of that under normal situation, as the reservoir water level declining dramatically from 175m to 145m. Thus, the influence of hydrodynamic pressure should be considered in the stability calculation.