Advanced Materials Research Vols. 243-249

Abstract: Shandong Qufu Xingtan Theater, originally built for an open-air theater, was designed as a one-time temporary structure with bolt ball junction double-layer regular pyramids grid structure roofing system. Because of the transformation of open-air structure system to an enclosed construction, some members of the space grid structure can not meet the required bearing capacity. According to the mechanical performance of space grid structures, the reinforcement methods of “circular steel jacketing” and “lateral support” are conducted, which are based on the analysis of the stress and stability characteristics of different grid members. By using the methods given above, the stress and slenderness ratio is decreased. The results indicate that the two reinforcement methods can reduce the difficulty in construction, shorten the construction period, and gain good economic and social benefit.

Abstract: Monolithic moving of the buildings has supplied a new choice for the urban planning and reforming. The paper studied the designing and construction of monolithic moving for a four-story frame structure building, and introduced a series of calculating methods and construction technology, including the arrangement of the track beam，the calculation of the underpinning joint, the calculation and selection of the underpinning system，the selection and arrangement of the rolling device, the construction controls of moving, and the connecting of the new foundation.

Abstract: This paper focuses on the characterization of flexural behavior of RC beams strengthened with Near-Surface Mounted (NSM) GFRP bars. Based on ABAQUS, the finite element model for the flexural behavior is established and the simulated results are compared with the test results. The parameters including the amount of GFRP bars, the embedment length of GFRP bars, the types of FRP bars, and the ratio of internal steel reinforcement in the beam for the flexural behavior are discussed. The simulated results show that there has a good agreement with the experiment results. The beams strengthened with NSM GFRP bars have a significant improvement in flexural stiffness and bending capacity. Further more, the analysis results on the parameters indicate that ultimate bearing capacity of the beam strengthened with NSM-GFRP bars gradually increases with the amount of FRP bars and the ratio of the longitudinal steel reinforcement. The mode of failure of the beam strengthened with the smaller embedment length of GFRP bars is not the rupture of GFRP bars. The different types of FRP bars have a great influence on the load-deflection curves of the beams.

Abstract: Due to the low design standards when constructed, limited construction materials, corrosion damage from natural environments and degeneration in normal use process, some reinforced concrete silos put up in the 1980s and 1990s are facing the troubles like decrease of bearing capacity, cracks and component damages, which are seriously affecting their normal use and bring certain security risks. Thus, the strengthening of these silos should be taken into account. In this paper, the positions that should be paid more attention when strengthened are obtained through finite element method analysis of a silo. Then the silo is strengthened with carbon fiber sheet through three different reinforcement conditions. The structure performances after being strengthened are analyzed, and the factors that affect the reinforcement effects are summarized.

Abstract: Based on the result of investigation of farmer’s house in Beijing, a finite element model of reinforced brick wall with a open hole was established, using the ANSYS finite element analysis software. Besides, several reinforcement ways were compared and analyzed. The differences of the maximum displacement and the stress value of different models in the same force condition were discussed. As a result, we put forward a reference reinforcement model.

Abstract: Overall 12 specimens were experimentally investigated in this paper to study the hysteretic behaviors of the concrete-filled circular CFRP-steel tubular (C-CFRP-CFST) beam-columns. The test results indicated that CFRP can provide transverse confinement effect and longitudinal strengthening effect for the concrete filled circular steel tubular (C-CFST) beam-columns effectively and the local buckling of the steel tube is deferred. With the increase of the strengthening factor of the longitudinal CFRP, the damage scale reduces.

Abstract: For reinforced concrete beams strengthened with prestressed carbon fiber reinforced polymer (CFRP) plates, design methods are derived for determining the allowable plate area or initial tension control stress of CFRP plate to achieve a targeted value of ductility. The derivation of equilibrium and compatibility equations for a rectangular cross section is presented. Base on the test of 2 reinforced concrete beams strengthened with prestressed CFRP plates, analytical results are compared with experimental results. Comparisons show that the design methods have good applicability. It can provide a reference for engineering application of strengthening design.

Abstract: After form a removal concrete cross ribbed beam floor in a commercial plaza, the vertical cracks are discovered, and the settlement analysis and reinforcement of a Cast-in-situ concrete floor are performed. The detection of the maximum crack is 0.3mm,and the Maximum settlement of cross ribbed beam is 48mm. By theoretical analysis, improper form removal during construction stage makes the actual floor force inconsistent with the design of a load transfer, which is the main reason of the excessive settlement in the cross ribbed beam. Through the economy, ease of handling in construction and other aspects of comparative analyses, the close beam side by epoxy grout and paste the carbon fiber under the beam to reinforce the cross ribbed beam. After reinforcement, no defect is discovered in the project so far.

Abstract: The rehabilitation properties of intelligent concrete beam reinforced with shape memory alloys (SMA) is investigated. In this study, SMA strands, made of 7 single wires, are used to replace the steel bars in ordinary concrete beam. The test of single point loading at the mid-span is conducted on the beam. The experiment has three stages including loading, unloading and heating the SMA strands. During heating the SMA strands by electrical current, the crack width can be reduced by taking the advantage of the shape memory effect of SMA strands. The results illustrate that SMA is a candidate material for rehabilitation of reinforced concrete structures.

Abstract: This document considered mechanical property of carbonated concrete and existing non-carbonated concrete, discussed the remaining effective area and mechanical property of the corroded steel bar and then compared the mechanical performance of CFRP reinforced old RC beam before and after secondary loading. The result shows that although the mechanical property of concrete and steel bar changed after secondary loading, the bearing capacity of normal section of old RC beam was significantly improved by bonding CFRP sheet. Moreover, the results of numerical simulation will be much closer to those of practical projects if we sufficiently consider the changes on mechanical performance of the materials.