Study On Early Stress Field Distribution And Simulation Analysis Of The Steel Concrete Composite Wall

Steel plate concrete composite shear wall structure plays an important role in the engineering construction,especially in the super high-rise and large-span structures.High performance concrete is often used in steel plate concrete composite shear walls,which can meet the requirements of high strength and super high pumping because of its remarkable effect of fluidity and self compacting.But during the construction,because of the preparation of the high performance concrete needs a large number of cement,so the hydration heat is large during the initial construction,it leads to form a temperature difference between inside and outside of the structure,during the cooling stage of the hydration heat,and because of the steel concrete composite shear wall structure is affected by the internal temperature shrinkage effect,it promotes the internal of the structure produce large tensile stress,meanwhile the structure is restrained by its internal steel plate and studs,then the structure cracks.In practical engineering,such as Tianjin 117 building and other major projects during the construction process,there have been appeared the cracking phenomenon of the steel concrete composite wall,and it seriously affect the durability of the structure.Therefore,it is very important to study the cracking of steel plate concrete composite shear wall due to the temperature field and temperature stress.First of all,the paper summarizes the research status of crack control in steel plate concrete composite shear wall in recent years,and then emphasize the theoretical knowledge of the temperature control and temperature cracks of the steel plate concrete composite wall.Secondly,develop a crack control scheme from three aspects,they are the construction of steel plate,the optimization of concrete mix ratio and the monitoring of steel plate.Finally,use the finite element software ABAQUS simulate the process of steel-concrete composite shear wall cracks which is caused by the changeable temperature,the simulation is mainly composed of two parts,they are the process of temperature change caused by hydration heat of concrete in the early stage of construction and the process of the stress variation in the steel plate concrete composite wall during the temperature drop stage.The main contents of the paperinclude:(1)The basic theory of temperature field and temperature stress and the finite element method are summarized;(2)In the formulating of the steel-concrete composite shear wall test scheme,several aspects of the research were carried out and improved,which they are the welding process and steel structure construction,large volume and high performance concrete optimization design,and at last,analyzed the monitoring data of 28d;(3)In this paper,the test wall is taken from the core tube wall of the B3 layer in a super high-rise building in Beijing,the height of the test wall is 4.8m,the thickness is 1.2m,the thickness of the steel plate is 38 mm.Through the analysis of the monitoring test wall characteristics,combined with the sensor layout experience of the similar projects,4 points are arranged in the 1/2 height of the plate,the 3~7 layer sensor is arranged at each measuring point according to different burying depth,each sensor is divided into two levels in vertical direction,In order to monitor the strain changes at different time and depth and the temperature changes of the steel plate at different time after pouring the concrete;(4)Through the second-development interface of the ABAQUS,compiled the HETVAL user subroutine of high performance concrete hydration heat and the hydration heat changes with the age;(5)Through the introduction of HETVAL subroutine,the temperature field of the steel plate concrete composite wall model is analyzed,and the theoretical simulation value and the measured value are compared and analyzed;(6)The thermal stress analysis of the steel plate concrete composite shear wall model is carried out by means of the smeared crack model.Finally,compare the experimental and finite element simulation results,we can reach the following conclusions: That is,the construction of the steel plate,the optimal design of the concrete and so on several aspects of the improved test wall,the distribution of the real cracks and the position reached consistent with the simulation results,it is proved that the optimization of the construction technology and concrete mix ratio of steel plate in the test is successful in controlling the early cracks of steelplate concrete composite shear wall,which has a positive effect on the study of early crack of steel plate concrete composite shear walls in the future.