Static Performance And Seismic Performance Of Cellular Steel Reinforced Recycled Lump Concrete Composite Beam

The advancement of industrialization and the treatment of solid waste are two problems that need to be solved urgently.The combination of prefabricated structure and recycled concrete structure provides a solution to these two problems,showing a promising application prospect.Based on this,this paper proposes a new type of cellular steel reinforced recycled lump concrete composite beam.In order to investigate the application feasibility of this type of composite beam,finite element analysis and experimental research were carried out in this thesis,so as to explore the static performance and seismic performance of the composite beam The main research contents and conclusions are as follows1.Finite element analysis of the flexural performance of celluar steel reinforced recycled lump concrete composite beams was carried out,to discuss the effects of the replacement rate of demolished concrete lumps and the expansion ratio.The flexural performance was also compared with that of solid-web steel reinforced concrete composite beam,cellular steel reinforced concrete beam and solid-web steel reinforced concrete beam.The research shows that:(1)the flexural bearing capacity of the composite beam and the cast-in-place beam are basically the same;(2)the replacement rate of the recycled lumps has no obvious effect on the bending resistance.When the recycled lumps replacement rate is not more than 20%,the bending resistance drops no more than 3%;(3)the bending capacity of composite beams tends to decrease slightly and then increase gradually as the expansion ratio increases.When the expansion ratio is between 1.3-1.5,it can effectively improve the bending resistance2.Finite element analysis of the shear performance of celluar steel reinforced recycled lump concrete composite beams was carried out,to discuss the effects of the replacement rate of demolished concrete lumps and the shear-span ratio.The shear performance was also compared with that of solid-web steel reinforced concrete composite beam.The research shows that:(1)the replacement rate of recycled lumps has no obvious effect on the shear resistance The ultimate shear capacity of the beams does not decrease by more than 4%;(2)when the shear span is relatively small(??1),the shear strength of the cellular steel reinforced concrete composite beam is lower than that of the solid web steel reinforced concrete composite beam;when the shear span ratio is increased to 1.5,the shear strength of the two is very close3.The seismic performance tests of 9 cellular steel reinforced recycled lump concrete composite beams were carried out.The effects of construction methods(cast-in-suit,prefabricated),the presence and spacing of shear studs,the type of concrete(Portland cement concrete,geopolymer concrete),the replacement rate of recycled lumps and the expansion ratio on the seismic performance of the composite beams were discussed.The research shows that(1)the composite beam can achieve the same effect as the cast-in-situ process;setting the shear studs on the upper flange can improve the load-bearing capacity of the cement concrete beam to a certain extent,but the bearing capacity of geopolymer concrete beams is less improved.(2)compared with the solid-web steel reinforced concrete composite beam,the positive bending moment bearing capacity is reduced,while the negative bending moment bearing capacity,the displacement ductility and energy dissipation capacity are improved;(3)the pre-yield stiffness,yield load,bearing capacity and energy dissipation capacity of geopolymer concrete beams are lower than that of cement concrete beams,but the post-yield stiffness,strength degradation and stiffness degradation are similar to the latter.4.The finite element analysis of the seismic performance of the cellular steel reinforced recycled lump concrete composite beam was carried out.The effects of cast-in-suit concrete strength,the replacement rate of recycled lumps,the cover thickness of cellular steel,the expansion ratio,the diameter of longitudinal bar,the thickness of flange and the thickness of web on the seismic performance of the composite beams were discussed.The research shows that:(1)the strength of the cast-in-place concrete and the replacement rate of the recycled lump have little effect on the seismic performance of the composite beam.The cover thickness of the steel beam has a certain influence on the ultimate bearing capacity.And the thickness of the cover is subjected to be 75mm;(2)as the expansion ratio increases,both the forward and reverse stiffness and ultimate load of the composite beam increase significantly.However,if the expansion ratio is too large,it will cause stress concentration near the holes in the web.It is recommended that the expansion ratio be 1.3-1.5...