Structural Performance Analysis Of Prestressed Concrete Hollow Slab With Rear Opening Hole

Prestressed concrete hollow slab has the advantages of save temslab,reduce mold,mold,avoid a lot of wet operation,save material,reduce the construction cost,and speed up the construction progress,shorten the construction period,save the construction site,civilized construction and the quality of the slab is stable and easy to control,although in the present construction has been rarely used,many areas have also eliminated the,but there was a large number of houses using prestressed concrete hollow slab,along with the social development,more and more the owner in order to satisfy the requirement of the daily production and life use,need to decorate the house,and make rear opening hole in the slab,For example,the arrangement of the drainage pipe,ground-type plug,cable boxes and so on,it will inevitably affect the structural performance of prestressed concrete hollow slab.At present,domestic and foreign scholars have little research on the structural performance of prestressed concrete hollow slabs with rear opening hole.This paper will use finite element software to analyze and study such slabs.In this paper,the influence factors of prestressed concrete hollow slab such as different size,opening hole position,opening hole size,opening hole shape,combined opening hole and whether the main bar is damaged are considered,based on the finite element software ABAQUS,the finite element analysis of the bending behavior of the hollow slab with rear opening holes under vertical static load is carried out.Researching the changes of load-mid-span deflection curve,load-steel bar strain curve and strain distribution of rear opening hole holloe slab,the crack load value and ultimate load value of the rear opening hole hollow slab were calculated.Then carbon fiber(CFRP)cloth is used to reinforce the structure under unreasonable opening hole conditions,the performance of the structure after reinforcement is analyzed and the data before and after reinforcement are compared.The results show that:(1)with the increase of the size of the slab,the structural performance of the slab becomes more and more unfavorable;The opening hole position in the middle span is the unfavorable opening hole position,in which the opening hole position at the side of the mid-span slab is the most unfavorable opening hole position,and the most favorable opening hole position is at the end of the slab.The opening hole injury main reinforcement have a great influence on the structural performance of the plate,the tensile stress increase obviously in the tensile zone,deflection increase and the rebar yield phenomenon appears.With the increase of the size of the opening hole,the structure performance of the slab becomes worse,and the adverse range increases.Square opening hole relative to round opening hole,the stress concentration at the opening hole is more obvious.In the combined opening hole slab,the combined opening hole is more disadvantageous to the structural performance of the slab than that before the combination.(2)the cracking load value and ultimate load value of the perforated slab decreased obviously,the cracking load value of the slab decreased by 27.3%?30.75%,and the ultimate load value decreased by 5.4%?25.7%.It is found that the deflection test of the slab meets the requirements,while the crack resistance and bearing capacity test of the slab do not meet the requirements.(3)based on the finite element analysis,the structural performance of reinforced prestressed concrete hollow slab with rear opening hole was analyzed.It was concluded that under normal service load,the structural performance of reinforced prestressed concrete hollow slab was significantly improved,the stress at the opening hole was significantly reduced,and the stress concentration was significantly improved.In the study of ultimate bearing capacity,the cracking load and ultimate load of the strengthened slab were significantly increased,the cracking load value of the slab increased by 25.0%?33.1%,and the ultimate load value increased by 26.4%?47.2%.After reinforcement,the deflection and bearing capacity of the rear perforated hollow slab can reach the state without opening hole,and even the bearing capacity can be improved.Reasonable reinforcement can make the deflection,crack resistance and bearing capacity of the rear perforated hollow slab meet the requirements.The formula for calculating the flexural capacity of rear opening hole prestressed concrete hollow slab reinforced with CFRP fabric is also presented in this paper.