Temperature Under The Action Of Anchor Specimen Pull-out Test

Post-installed rebar connection belongs to a post-installed anchor bar technology,which are widely used in structure strengthening and retrofitting.Post-installed rebar system include steel, adhesive, concrete, reinforced-colloidal and concrete-colloidal, the mechanical properties of the five elements have an important impact on the mechanical behavior of post-installed rebar structure.At present,most foreign and native researches about post-installed rebar are in normal conditions, its application and research in the special environment is less. In this dissertation, the mechanical behavior of post-installed rebar structure in theory is analysised, the thermal-stress on post-installed rebar specimens with theoretical solution and finite element are put forward, pullout experiment on specimens under temperature and their general law of bond-slip behavior are given, BP neural network model simulate and predict current and test data are used.The study carry out in the dissertation includes the following aspects:(1) Based on the recent relevant achievements obtained at home and abroad,the anchorage performance experiments, tensile capacity calculation methods,bar-glue and special mechanical properties of post-installed rebar are summarized and presented.(2) Each bond-interface of bond stress is analysised and the main factors affect tensile capacity in post-installed bar structural are summarized, their tensile capacity are calculated and every tensile failure mode according to the kind of material is determined.Through theoretical solution and finite element analysis with thermal-stress on post-installed rebar specimens, destruction and convergence criteria with finite element analysis are put forward,bond-slip failure law of the specimens under temperature in theory are proposed.(3) The experiment specimens are heated in a box-electric furnace, the pullout strength of normal temperature, temperature after natural cooling,constant temperature with pullout loading under temperature,constant loading with gradual heating under temperature are studied,their bar-glue temperature are measured through embedded thermal couple in the specimens.Based on the summarize of the thermal and mechanical properties of anchorage materials under temperature, post-installed bar structure of its safety under temperature are determined.(4) Learning and simulation capabilities of BP network model are used, the test temperature, concrete strength, steel anchor length, anchor diameter on the ultimate tensile capacity are considered,post-installed rebar specimens under temperature of their ultimate tensile capacity with BP network prediction model is established, it can reflect the ultimate strength under temperature and its main nonlinear relationship among the factors well.The post-installed rebar specimens experiment under constant temperature, different temperature and different temperature after cool are studied, it can provide the structure for fire resistance of embedded steel bars a reference for further study. BP network prediction model can provide fire resistance of embedded steel bars a new way.