Experimental Study On Shrinkage Of High Strength Concrete Reinforced With Studs

With the continuous development of economy and society,high-rise and super high-rise buildings continue to emerge in China.In order to meet the requirements of super large capacity and high durability of super high-rise buildings,and to ensure the use of space,steel plate concrete composite shear wall has been widely used in high-rise and super high-rise buildings because of its excellent mechanical properties and low structural space occupancy.However,a large number of engineering practice shows that the steel plate concrete composite shear wall has a more serious cracking problem than the traditional reinforced concrete shear wall.This is because the steel plate concrete composite shear wall is widely used in the high strength and high performance concrete,at the same time,because of its own structural characteristics,it has more complex constraints than the traditional structure.Cracking has seriously affected the building waterproof and suitable function,reduces the bearing capacity of the concrete structure,and provides a channel for the invasion of water and harmful medium.So the durability of super high-rise buildings is largely reduced.At present,the crack resistance analysis and control of steel plate concrete composite shear wall is still based on the research results of anti-cracking of reinforced concrete structure.From a large number of engineering practice,the effect is not very good.The internal constraints of high strength concrete in steel plate concrete composite shear wall are complex,including the coupling effects of steel bars,studs and steel plates.Some scholars have studied the shrinkage of high strength concrete under steel bars,but the study of shrinkage of high strength concrete under studs is still in the blank.Therefore,this paper makes a systematic and thorough study on it.The main conclusions of this paper are as follows:(1)Compared with the stud constraints of high strength concrete shrinkage and plain concrete shrinkage,both the first time and the size of the peak value are decreased for the former.It is shown that it can effectively reduce the early shrinkage of high strength concrete after setting the studs.But if you set the number and spacing of studs are not sufficient to meet the requirements of anti-cracking,it may pose a risk to the early cracking of high strength concrete.(2)Compared to the shrinkage curve of reinforced concrete,the shrinkage of high strength concrete reinforced with studs is not a big difference than plain concrete.But it can enhance the ability of confined concrete by increasing the number or decreasing the spacing between the studs.Thus,the shrinkage of concrete is significantly reduced.(3)The studs after brushing oil will greatly reduce the restriction of concrete,and greatly weaken the bonding between the studs and concrete.So in the actual construction,the oil stain of studs’ surface should be wiped after welding.And oil proof measures should be done well.(4)With the increase of the restraint degree of the specimen,the increase of the value and the ratio of the end shrinkage compared to the central shrinkage is decreased.And the greater the increased restraint degree,the more significant that the reduction of the value and the ratio of the end shrinkage increased.It is shown that the restraining effect of restraining strip on the adjacent concrete strip is improved with the increase of the restraint degree of the specimen.(5)In the constraints capacity of high-strength concrete,the greatest impact is the spacing of studs,then stud diameter,the last is stud height.(6)The finite element model of S-9 group is established by using ABAQUS software,and the simulation results are compared with the experimental results.They are in good agreement.It is shown that the finite element model is reliable,and it can be used to analyze the stress of high strength concrete under the constraint of studs.It is shown that concrete and stud roots at the junction have the phenomenon of stress concentration through the stress analysis,where is also easy to produce cracks.