| Full-bolted prefabricated concrete structure(BPC structure)is a full-dry on-site prefabricated structure.Its prefabricated components can realize standardized production in factories.The site construction and assembly of the main structure are simple,the construction cycle is short,and the modular advantages fit the BIM technology,so it has a good application prospect.To popularize prefabricated buildings is in line with the development strategy of national housing industrialization.At present,there are many researches on the tensile anchoring performance of anchor bolt in foreign countries,and the design method of anchor bolt is given in relevant codes.In China,there are also a lot of relevant studies on tensile anchor bolt,but most of the domestic and foreign studies are based on group anchor to study the relationship between anchor length,protective layer thickness and anchor bolt anchoring performance,and there are few studies on the minimum section size of independent anchor bolt members.Therefore,In this paper,six groups of small-section J-bolt foundations were designed based on the economical and applicable idea,and the test model was established by ABAQUS software to analyze the anchoring performance of independent bolts under different sections,buried depths,hoop ratios and reinforcement modes.Research shows that:(1)Through 6 groups of anchor bolt pull-out tests with small sections,the failure of anchor bolt beam with narrow sections mainly includes vertical crack failure,oblique crack failure and anchor bolt yield slip failure.When the restraining capacity of the beam is insufficient,the maximum bearing capacity of the bolt is determined by the restraining capacity of the concrete.The bearing capacity of the bolt when vertical cracks appear is smaller than that when the beam is destroyed by oblique cracks.There is not much difference between the bearing capacity and the maximum bearing capacity when inclined crack failure occurs.(2)The test shows that for the larger diameter J-shaped anchor bolt,the thickness of the side protective layer of 5D0 is smaller,and the thickness of the bottom protective layer of 5D0 and 100mm is also smaller.According to GB50010-2010 Code for Design of Concrete Structures,it is determined that the anchoring length of J-type anchor bolt is too large,and the degree of the anchoring length is about 32% of the code.(3)The numerical simulation model of J-shaped anchor beam was established based on the test.The anchor displacement was within the range of 20 mm,and the analysis results were basically consistent with the test results.With the aid of finite element analysis software to simulate the whole process of the concrete foundation beam damage,damage to the law of development,and thus obtained the Liang Mao bolt under the action of drawing crack forming mechanism,the results show that concrete around the anchor bolt and the hook damage first,with the constant extension injury,anchor bolt deformation occurred in hook,when cracks extend to the concrete surface,and the results are basically identical.(4)Under a certain hoop ratio,the influence of burial depth on the maximum bearing capacity is the most obvious when the section width is 200 mm,and the improvement degree of burial depth on the maximum bearing capacity decreases at a rate of 10% with the increase of the section width at 20 mm.When the buried depth is constant,the yield load of the section width of 200 mm is 25% different from that of the section width of 220 mm.However,the yield loads of 220 mm,240mm,260 mm,280mm and 280 mm increase linearly,the yield loads of280 mm to 300 mm and 320 mm to 360 mm are almost unchanged,and the yield loads of 300 mm and 320 mm increase linearly.The maximum bearing capacity increases linearly with the increase of the section.When the width of the section is up to 320 mm and 360 mm,the maximum bearing capacity will not increase.When the buried depth is certain,the increase of the section width(a certain range)will obviously improve the bearing capacity,and will not increase until the anchor bolt reaches the yield bearing capacity.When the section is constant,the hoop ratio has less than 3% effect on the maximum bearing capacity,so the hoop ratio has no obvious effect on the maximum bearing capacity.The maximum bearing capacity and the maximum bearing capacity can be increased by less than 7% by the addition of lateral rifting bars,so the effect of the addition of lateral rifting bars on the yield load and the maximum bearing capacity is not obvious. |
