Applied Mechanics and Materials Vols. 351-352

Abstract: The article tries to describe the application of CFRP in frame beam used in the reinforce of civil engineering through some concrete engineering examples. Futuremore ,the writer analysises the reinforce ment principle,construction preparation construction process and the construction matters in details. As there doesnt exist construction acceptance criteria and other specification of carbon fiber used in the reinforced repairment at home, thus in this article, the writer aims at analysising the usage of carbon fiber in the construction of civil engineering structures. The result of shows that there are broad prospects of the carbon fiber reinforcement in Engineering repairment, the reinforcement and alterations of housing construction and Bridge Engineering.

Abstract: In the paper are discussed the likely causes of the collapse and the temporary safety features adopted to secure a collapsed portion of the Historic Walls of the city of Pistoia (Italy). The walls of medieval origin, affected by various subsequent modifications and alterations, have been subjected to a sudden collapse, after a period of heavy rain, for a length of about 25 meters. Hereby are described the probable causes of the collapse, due to a poor quality of the walls (external façades with external layer made up of river pebbles and inner filling material in-coherent), height of building is not modest (approximately eleven meters), a significant differential in height between the two faces (about four meters) and a not unlikely rotation of the base. It is proposed a technique of temporary reinforcement with a system of steel tie-beams and braces with a view to the work of reconstruction of the partially collapsed and consolidation of the lateral parts of wall.

Abstract: The idea to apply temporary and precautionary seismic reinforcements to protect artistic assets in historical buildings is hereby presented. The example of the San Frediano Church in Pisa is addressed to show the improvements in its seismic response due to steel wire ropes applied to arches and columns. Numerical analysis demonstrate the reduction of the shear force at the base of the stone columns. The proposed reinforcements are reversible, temporary and with low aesthetic impact: they can be quickly installed in the beginning of seismic events, as an evolution of the techniques adopted after the last Italian earthquakes (Abruzzo 2009 Emilia 2012).

Abstract: The technique of strengthening structures with prestressing CFRP can improve the load-carrying behavior of reinforced concrete structures and has gained more and more attention recent years. However the research about behavior of the pre-cracked structures after retrofit is rather limited. In this paper two RC beams with large dimension were constructed. One beam was strengthened by non-prestressed CFRP plate serving as reference beam. And the other beam had been loaded to its yielding load before it was strengthened with a prestressed CFRP plate. The monotonic tests were conducted to investigate the effect of strengthening with prestressed CFRP on the behavior of the pre-damaged beam. Based on the experiment results, the comparison of behavior between the beam with non-prestressed CFRP plate and the pre-cracked beam with prestressed CFRP was conducted. The experiment results indicated that although having been loaded to its steel yielding before being strengthened, the specimen with prestressed CFRP plate had a load-carrying capacity no less than the intact beam with non-prestressed CFRP plate. Despite the serious damages of section, the stiffness of the pre-cracked specimen was almost equal to that of the reference specimen, which indicates that the technique of strengthening structures with prestressed CFRP plates can be effective in the retrofit of the seriously cracked reinforced concrete structures.

Abstract: In this paper, we research wire mesh and polymer mortar strengthening of the wire rope end which use MLJ building structural adhesive anchorage in experiment. This text discusses the building structural adhesive for wire rope anchorage performance, through the experiment and data analysis showed that the modified structural adhesive anchorage cable can give full play to the wire rope high strength properties.

Abstract: This paper indicates cracking mechanism and strengthening method of reinfoced concrete hammerhead piers. A field investigation phase has been undertaken in conjunction with analytical studies to model the cracking process. It is shown that the front cracks in the pier cap developed because the bending tensile stress far exceeds the tensile strength, while the side crack caused by none bursting reinforcement. Based on the analysis results, an internally prestressing approach is provided, and the retrofitting effect is verified by finite element analysis. Strengthening with internally prestressed tendons of bridge pier cap is proven to be a reliable and relatively easy-to-install technique.

Abstract: This paper makes some experiments on steel wire rope terminal fixture connection in strengthening with steel wire mesh and polymer mortar, discusses the performance of terminal fixture connection and the analysis of the experiments and dates show that: The connection of the three aluminium-alloy swaged ferrules with the same arranged for steel wire rope or two wire rope grips meet the design requirements of rules and regulations, and three wire rope grips can give full play to the high tensile mechanical performance of steel wire rope.

Abstract: In order to check out the effects of the method how the FRP sheets wrapped on the axial behavior of timber columns confined by CFRP sheet, 6 short columns were confined with CFRP sheets in different wrapped ways, i.e. toroidal, single helix, double helix and cross helix. Another column in the same size was prepared as contrast. The ultimate carrying capacity of the specimens was analyzed as well as the load-displacement curves and strain-stress relationships. The comparison of the ultimate carrying capacity showed significant enhancement when the specimens were confined in any ways, and the way wrapping FRP sheets in the toroidal direction was more efficient than other ways in which the FRP sheets wrapped in the experiment. The analysis of the load-displacement curves indicate that the stiffness of the specimens was improved by the reinforcement with FRP sheets in any ways, however, the improvement of the ultimate carrying capacity and the stiffness was in the cost of the ductility. The comparison of the FRPs train between the specimens with toroidal wrapping method and the helix ones can clearly explain the lower efficiency in the enhancement of ultimate carrying capacity of the specimens with helix wrapping methods.

Abstract: Stiff frame was the important structural member in construction of replacement of closure segment for prestressed concrete cable-stayed bridges. To establish the design calculation method of it and reveal its variation of internal forces with construction stages of replacement, some configurations and its working process of stiff frame was introduced. Based on construction stage analysis of replacement, calculation methods of its strength and stability were given. Through FEM results, influence of stiff frame to structural dynamic property and global stability of whole bridge were described. Analysis results showed, it was appropriate to consider each section steel of stiff frame as eccentric compression member. During construction, the transversal global property of stiff frame and the security of its link with main girder must be valued. Construction results also proved, the theoretical calculation method could reflect the actual structural state of stiff frame, and its result was conservative. Analysis on stiff frame was an important part of replacement of closure segment, and could provide ways and references for construction control of replacement of closure segment.

Abstract: Fiber reinforced polymers (FRP) can be used to restore the stiffness and bearing capacity of the damaged steel structures and improve their fatigue resistance. The reinforcement technology has the advantages of fast construction, short cycle, environmental protection and can greatly reduce the cost of the projects. Because there is a large number of steel structure need reinforced in our country, the market potential is tremendous. With localization of FRP and technology advancement of material production, the reinforcement technology will have a stronger competitiveness. Combined with material properties, comprehensive cost, construction method, maintenance and other aspects of FRP, a comprehensive technical and economic analysis has been done for FRP reinforcement and repair technology of steel structure. It could be provided a theory basis and application reference for existing steel repair reinforcement technology.