Advanced Materials Research Vols. 919-921

Abstract: The beam-column joint is the key component of a RC structure and also the hub of stress transferring between beam and column. It is the major part for ensuring enough stiffness, ductility and good energy dissipation capacity of the RC frame. In order to simulate the beam-column joints under cyclic loading, a model based on OpeeSees was studied. OpenSees has advantages over other nonlinear analysis software in the improvement of algorithms. Comparison of simulated and observed hysteretic curve indicates that the proposed model is appropriate.

Abstract: A dyke construction was dealed with geotextile-encased sand columns. The dyke was used to enclose a polder in Hamburg-Finkenwerder, Germany. With the help of geotextile, the columns can be used in very soft soils , even undrained shear strength c_u < 15 kN/m2, without excessive bulging. After the system is installed, the dike can be filled immediately. To analysis observed data of the long-term settlements in the dyke, three stages can be gotten i.e. "Primary settlements" - "Secondary settlements" - "Creep settlements". Most settlements occurred during the primary filling, while, only little settlements appeared after that construction was accomplished. The settlement rate decreases from the first settlement stage to the last one. No jump takes place when unloading soft soil. Furthermore, the method shorten time and saved a lot of money.

Abstract: The idea, procedures and equation of dynamic of analysis of an actual power transmission tower system by dynamic elastic-plastic time history were introduced. Considering P-DETA effect, the base shear forces and curves of top displacement time history were obtained. P-DETA effects on seismic performance of the transmission tower were calculated. The paper can be reference for the analysis of static elastic-plastic.

Abstract: In order to investigate the bearing behavior of composite beam with different web openings. Six composite beams were analyzed by using the finite element program ANSYS and the shape of openings was different. The results show that the shape of opening has a significant influence on the bearing capacity and deformation capacity of composite beams with web openings. Because stress concentration is relatively small, the force performance of circular web opening is more reasonable and has the largest bearing capacity and deformation capacity.

Abstract: It’s imperative for thermal power plant to add denitrification system. Denitrification facility is usually arranged between economizer and air pre-heater, which may unavoidably collide with vertical bracings of boiler frame. Based on the denitrification project of a power plant in north China, this paper puts forward a simplified analysis method and a practical reinforcement scheme for boiler frame which needs to remove some bracings. The method is on the basis of effects of vertical bracings on boiler frame. Three models including original structure, demolished one and reinforced one are conducted to study structural behaviour under horizontal loads in SAP2000 software. Considering that bracings between the columns bear horizontal loads mainly and increase the horizontal stiffness of frame, reinforcement design is based on the principle of equal rigidity that the horizontal floor displacement and the proportion of horizontal loads boiler columns bear are approximately same as original.

Abstract: This paper presents an experimental investigation into the axial strain measurement method of fiber reinforced polymer (FRP)-confined normal-and high-strength concrete (NSC and HSC). A total of 15 FRP-confined concrete specimens with circular cross-sections were tested under monotonic axial compression. Axial strain recordings were compared on specimens instrumented with three different measurement methods: axial strain gauges and full-and mid-height linear variable displacement transformers (LVDTs). The ultimate conditions are tabulated for each measurement method and key experimental outcomes discussed. The results indicate that axial strains of FRP-confined HSC are highly sensitive to the instrumentation arrangement and significant differences occur in the results obtained from different measurement methods.

Abstract: It is well established that lateral confinement of concrete enhances its axial strength and deformability. It is often assumed that, at a same level of confining pressure, the axial compressive stress and strain of fiber reinforced polymer (FRP)-confined concrete at a given lateral strain are the same as those in concrete actively confined concrete. To assess the validity of this assumption, an experimental program relating both types of confinement systems was conducted. 25 FRP-confined and actively confined high-strength concrete (HSC) specimens cast from a same batch of concrete were tested under axial compression. The axial stress-strain and lateral strain-axial strain curves obtained from the two different confinement systems were assessed. The results indicate that, at a given axial strain, lateral strains of actively confined and FRP-confined concretes correspond, when they are subjected to the same lateral confining pressure. However, it is observed that, at these points of intersections on axial strain-lateral strain curves, FRP-confined concrete exhibits a lower axial stress than the actively confined concrete, indicating that the aforementioned assumption is not accurate. The test results indicate that the difference in the axial stresses of FRP-confined and actively confined HSC becomes more significant with an increase in the level of confining pressure.

Abstract: The geometric shape and internal forces were monitored during the construction of the hypostatic framework structure which is a composite system of steel beam and arch. The displace settlement was measured for the control of the geometric shape. And nine vibrating wire strain gauges were embedded on the key sections for the real time control of internal force. In order to cancel out the interference of the temperature variation effectively, displace settlement and internal forces were monitored around the clock at different time points. Then the measured values were compared with the theoretical values. Based on the measurement of temperature variation and strain, the settlement during the process of frame construction can be surely ascribed to thermal stress in the high redundancy structure. It should pay close attention to the changes in the future similar steel Beam Arch Composite Bridge construction and monitoring system.

Abstract: The cast-in-situ reinforced concrete grillage shear wall system with non-dismantling formwork is a new type of structural system characterized by load-bearing and thermal insulation, and the research on the construction technique is crucial to its promotion and application. Combined with the pilot building, the key technology and construction measures are introduced in this paper, which can provide reference for the related projects in future.