The Bonding Anchorage Performance Experimental Study Of Bearing And Thermal Insulation Glazed Hollow Bead Concrete

Bearing and thermal insulation glazed hollow bead concrete,which combines bearing with thermal insulation capacity,is a new kind of energy saving green building material.The characteristics and advantages of this concrete are with a low thermal conductivity closed to heat-insulation material and a high compressive strength the same to ordinary concrete.Due to the performance characteristic of this concrete,when it is used in concrete structure,can not only reduce its self-weight and improve the seismic performance of structure,and can also significantly reduce the energy consumption of building in the whole life cycle.The research and application of this concrete,can not only echo with the energy-saving and emission-reduction at this stage,but also meet the strategy requirements of global sustainable development.The prerequisite of thermal insulation concrete can be used in the concrete structure is that the bond and anchor performance between concrete and bar is reliable.In the paper,based on the preliminary work a study of bond-anchorage issue need to be solved in the design and performance analysis of concrete structure,is developed.The main works are as follows:(1)The experimental study of the bond and anchor performance of bearing and thermal insulation glazed hollow bead concrete and steel in the normal service condition is developed.The 36 specimens,with different strength grades,different shape and diameter of reinforced as well as different anchorage length,are designed.The pull-out test is used to obtain the bond-slip curves of the 36 specimens,and on the basis,the failure modes and characteristics of the each stage of bonding anchorage loading process are researched,as well as the bond-anchorage mechanism of thermal insulation concrete and steel is also analysed.Through the test,the influence law of the experimental parameters such as concrete strength,the cover thickness,anchorage length and reinforced diameter effect on bonding anchorage performance of ribbed bar and bearing and thermal insulation glazed hollow bead concrete is revealed,and combining with theoretical analysis,the calculation formula of ultimate bond strength of ribbed bar and thermal insulation concrete is proposed,as well as combining with the present specification and reliability analysis,the anchorage length of ribbed bar in the thermal insulation concrete is advised,so as to can provide foundation for structure design in the normal service condition.(2)Under consideration for the adverse working environment of thermal insulation concrete in the cold areas,the bonding anchorage performance and degradation mechanism of reinforced and bearing and thermal insulation glazed hollow bead concrete after freeze-thaw cycles is researched.The quick freezing method is used to carry out freezing and thawing test,in the basis,the failure mode of reinforced concrete after freeze-thaw is analysed,the similarities and differences of freezing-thawing resisting performance between thermal insulation concrete and ordinary concrete are compared,the degradation law of reinforcement and thermal insulation concrete after freeze-thaw cycles is summarized,the parameters such as concrete strength,the cover thickness,anchorage length and reinforcement diameter effect on the bonding anchorage performance after freeze-thaw is analyzed,through theoretical analysis the deterioration mechanism of the performance is revealed,and the calculation formula of ultimate bond strength of ribbed bar and thermal insulation concrete after freeze-thaw cycles is proposed,so as to can provide the design parameters and computing method for the durability design and maintenance and reinforcement of thermal insulation concrete in the cold and chilliness area of our country.Through experimental study and theoretical analysis it indicates that,the proposed calculation formula of ultimate bond strength of ribbed bar and thermal insulation concrete in normal service condition is?u=(0.69 +1.42d/la)(1.68 + 1.56c/d)f,t,s,as well as the design calculation value of anchorage length of HRB335 reinforcement in the thermal insulation concrete which is obtained by reliability analysis meets the related requirements of the current concrete structure design code,therefore the structure can be designed according to the current concrete structure design code;after freeze-thaw,the proposed calculation formula of ultimate bond strength of ribbed bar and thermal insulation concrete is ?u =(0.67+1.44d/la)(2.31+1.43c/d)ft,s(50),as well as compared with ordinary concrete,the damage of thermal insulation after freeze-thaw is less,and the bonding anchorage performance of thermal insulation concrete is superior to ordinary concrete.