| Steel bonded reinforcement is a common method for flexural strengthening of reinforced concrete structures,but the failure of debonding and fire under the condition of fire is the key problem to restrict its reliability.Therefore,the researchers put forward the method of anchor steel plate reinforcement.Through the anchor bolt directly anchoring steel plate,not only improves the flexural bearing capacity,but also effectively avoids the peeling failure.When the ordinary anchor bolt is installed,there is a gap between the anchor rod and the steel plate,which leads to the uncoordinated force of the anchor group and the reinforcement effect is reduced.The direct shear anchor bolt developed by our team has realized the gapless contact between the anchor rod and the steel plate,and has given full play to the shear resistance of the group anchor,and the reinforcement effect is good.In view of the fire,the adhesive has been rapidly lost,so the methods used in the present study are to directly anchor the steel plate.However,in practical engineering,in order to avoid steel corrosion and increase the durability of the structure,construction of glue between the steel plate and concrete,thereby strengthening for anchor bolt bonding steel plate,and the study of the consolidation mode is still almost blank.In order to understand the flexural performance of the reinforcement method which is used in the practical engineering project,and to evaluate the best reinforcement method,the static failure tests of four full-scale beams with the same section and reinforcement are carried out.By comparing the results of the test and economic indicators,the three methods are comprehensively evaluated.The following research work is proceeded.(1)The types,working principles,failure modes and influencing factors of the anchor bolt in the engineering project are summarized,and the bending mechanism and the related calculation formulas are proposed;(2)The design and manufacture of 4 full-scale beams are completed,including the unreinforced beam,the U type hoop steel bonding steel plate reinforcement beam,the ordinary bolting and bonding steel plate reinforcement beam and the direct shear bolting and bonding steel plate reinforcement beam.By comparing the load value,midspan deflection,steel plate strain,crack development and steel plate stripping,the flexural properties of the three strengthening methods are evaluated.(3)The economic performance of the three kinds of reinforcement methods are evaluated by comparing the amount of steel and the construction period;(4)The finite element software analysis and Simulation of the direct shear type anchor bolt bonded steel beam is carried out.The main conclusions are as follows.(1)The bending mechanism of bolting and bonding steel plate system is that the concrete bears the pressure force,the tensile steel and the steel plate bear the tensile force,and the three resist the external load together.The whole process can be divided into elastic stage,elastic-plastic stage and failure stage;(2)Compared with the performance of flexural strengthening,it is found that the performance of the direct shear bolting and bonding steel plate is best,the performance of U type hoop steel bonding steel plate is the second,and the performance of the ordinary bolting and bonding steel plate is the worst;(3)Compared with the engineering economy,it is found that the performance of the two kinds of anchor bolting and bonding steel plate is similar,which is better than the performance U type hoop steel bonding steel plate;(4)The results of finite element analysis are in agreement with the experimental results,which verifies the reliability of the direct shear bolting and bonding steel plate reinforcement method.(5)It is suggested that the direct shear bolting and bonding steel plate reinforcement method is preferred in the practical engineering project.The innovation of this paper:(1)This paper uses the technology of steel plate reinforcement by direct shear anchor bolt,which is developed by our research team and has obtained the invention patent;(2)This paper finds the difference between the theoretical research and the practical engineering in strengthening construction by comparing with the practical engineering construction for the first time,and studies the flexural performance of three kinds of reinforcement methods in the actual engineering;(3)As a comparative study of the flexural properties of three external steel plates under high temperature in the later stage of the study. |
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