| Using the advantages of the industrialization of the prefabricated building,the traditional wet operation of the passive house is changed into the assembly operation,which greatly improves the quality of the construction project and the comprehensive benefit of the building.It is the development direction of the passive house in the future.The prefabricated concrete sandwich thermal insulation wall panel is an important component of the prefabricated passive house,which has good thermal insulation performance,and can achieve the integrated design and production of decoration,thermal insulation and structure,which is very in line with the development requirements of building industrialization.As an important part of sandwich panel,the connector should not only have enough mechanical properties,play the role of transferring the load of inner and outer blade wall panel,but also meet the requirements of thermal performance.At present,there are two types of connectors in the common precast concrete sandwich panel: metal and FRP connectors.The metal connectors have high bearing capacity but large heat loss and high price;the FRP connectors have small heat loss but low bearing capacity and high cost for secondary processing.Because passive hoouse has higher requirements for thermal insulation performance,and the thickness of thermal insulation layer is larger,the existing metal or FRP connectors cannot meet the requirements of passive house for low heat loss and high bearing capacity,so it is urgent to carry out the research and development of new connectors to meet the requirements of passive building.In this paper,a new type of BFRP connector for prefabricated sandwich wall panel of prefabricated passive house is proposed.The basic mechanical properties,bearing capacity and bending resistance of concrete sandwich panel with the connector are systematically studied by experimental research and theoretical analysis.The main research work and achievements are as follows:1.Starting from the basic mechanical properties of BFRP connection materials,this paper has carried out the tests of tensile strength,tensile modulus,interlaminar shear strength,shear strength,bending strength,bending modulus and other mechanical properties of four kinds of BFRP reinforcement materials,as well as the tests of residual tensile strength and residual interlaminar shear strength of reinforcement materials after accelerated corrosion in high temperature and alkaline environment.The results show that The BFRP bars with a diameter of more than 8mm meet the material performance requirements of FRP connectors and have sufficient strength and safety reserves,so it is an ideal raw material for FRP connectors.2.For the pull-out performance of BFRP connectors,the pull-out test of straight anchor was carried out,and the pull-out capacity of three kinds of diameter BFRP connectors was determined when the anchorage depth was 50 mm.The standard values of the pull-out capacity of the connectors with the diameters of 12 mm,10 mm and 8 mm were 26.47 kN,23.68 kN and 20.47 kN respectively,which were higher than the requirements of the connectors.3.The double shear and combined double shear tests were carried out on the shear capacity of BFRP connectors.The influences of the installation angle,the diameter of the connectors,the thickness of the insulation layer on the shear capacity and the shear rigidity were compared and analyzed.The more appropriate installation angle of BFRP connectors was determined to be 60 °.In order to give full play to the performance advantages of BFRP connectors,the span ratio of the connectors(connectors)was determined The ratio of net span to diameter)should not be greater than 15.4.Based on the one-way four point bending test of precast concrete sandwich panel,the flexural performance of BFRP connectors with different spacing is studied.The flexural performance of sandwich panel with BFRP connectors and cross-section GFRP connectors is compared,and the combination degree of elastic stage and ultimate stage before cracking of sandwich panel is evaluated theoretically.The results show that: the sandwich plate with BFRP connectors has high displacement ductility coefficient and strong deformation capacity;the bending capacity of sandwich plate is related to the spacing of connectors;the bending performance of sandwich plate with BFRP connectors is better than that with GFRP connectors.5.Based on the above research,a design process and safety evaluation method of BFRP connector layout are proposed,which can be used as a reference for the design of BFRP connector layout in practical engineering projects. |
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