Study On Cracking Performance Of Basalt Fiber Reinforced Steel-concrete Composite Beams Under Hogging Moment

Steel-concrete Composite Beams are joined together by steel beams and concrete slabs through shear connectors.The components have good integrity and ductility,lower section height and lighter weight.It can be used as a formwork support for concrete slabs during construction,saving the economic cost.Therefore,it has been widely used in the fields of architecture and bridge structure.However,the hogging moment zone at the support of the steel-concrete composite beam will appear the steel beam in compression and the concrete slab flange in tension,which will cause cracking of the concrete.When the cracks are large enough,water or other corrosive liquids will penetrate and accelerate the corrosion of the steel bars and studs,which affect the durability of the structures and increase the maintenance cost of the actual project later.Some researchers have studied the influence of steel fiber on the bending behavior of composite beams.The incorporation of steel fiber into the concrete delays the speed of crack growth and controls the width of the cracks.Compared with steel fiber,basalt fiber can also improve the performance of crack arresting of concrete.In addition,basalt fiber is a green and environmentally friendly inorganic non-metallic fiber with good corrosion resistance and high performance-price ratio.Thus this thesis intends to provide the analysis on the crack development of concrete under the hogging moment of basalt fiber reinforced Steel-concrete Composite Beams.Five basalt fiber reinforced concrete beams were tested under the hogging moment to get the performance of crack arresting.Based on the experimental results,the crack propagation process was obtained.Crack width of the concrete and steel strain during the loading process were analyzed.The effects of different basalt fiber parameters on the maximum crack width,crack spacing and crack length of the specimen were investigated.Based on the research of basalt fiber reinforced concrete beam,four basalt fiber reinforced Steel-concrete Composite Beams were further designed to test the the performance of crack arresting under hogging moment.The mid-span load-maximun crack width curve and the steel strain-maxmium crack width curve of the test beams were analyzed.The effects of basalt fiber incorporation way and basalt fiber volume fraction on the crack of Steel-concrete Composite Beams were studied.Based on the calculation formula of crack width of reinforced concrete beams,the factors affecting the crack width of basalt fiber reinforced concrete beams were researched and a simplified formula for calculating the crack width of basalt fiber concrete beams was established.The experimental results were compared with the theoretical calculation results to verify the rationality of the calculation formula parameters.The calculation theory of the maximum crack width of basalt fiber reinforced Steel-concrete Composite Beams were achieved.The calculation formula of cracks of basalt fiber reinforced Steel-concrete Composite Beams under hogging moment was established,which provides reasonable suggestions for the crack control of Steel-concrete Composite Beams under hogging moments in practical engineering.