Mechanical Analysis Of Three Kinds Of Early Dismantling Formwork

Early dismantling template technology shorts the span of concentrate floors through the introduction of temporary support,and creates the temporary support layout that is more than 2.In this case it can meet the requirements of the specification in the form removal and dismantles templates earlier.Early dismantling template technology improves the construction efficiency and reduces the cost of the template project by reducing the amount of input and occupation time of the template,supporting system,connecting piece and time.By collecting the domestic and foreign about early dismantling template of relevant information this paper`s work contains the follows:(1)Calculating cracking load of the ribbon and cross support.The ribbon support uses t beam model and plate model to calculate.The results show that the plate model calculation is safer.When using the plate model the cracking load of cross support is8%~12% higher than the ribbon support.Due to existing a small area of the high stress,it should be checked by the formula of punching shear failure in the standard.(2)Combining with engineering practice and the minimum conditions of specification requirements create the concrete slab finite element model which is used the early dismantling template technology.Deflection,compression stress and tensile stress of the floor is analyzed.Deflection analysis shows that the maximum deflection of the floor increases when the span growing The maximum deflection of the floor is not the same as the support form,the maximum deflection of the floor is from small to large in order: cross support,strip support and point support.The variation range of the maximum deflection value is0.119mm~0.646 mm.Compression stress analysis shows that with the increasing of the span,the maximum compression stress in the floor increases gradually.The risk points of compression stress are at the point of the short side of the floor is used as the band,cross and point support.Compression stress analysis shows that with the increasing of the span,the maximum compression stress in the floor increases gradually.The risk of compression stress at the point of the short side of the floor is used as the band,cross and point support.When point support is used,the support is also a dangerous point of the compression stress.Tensile stress analysis shows that with the increasing of the span,the maximum compression stress in the floor increases gradually.After the early dismantling of the belt,cross and point support,the risk point of tension stress is at the support point,which is different from the position of the pressure stress risk point.(3)Numerical simulates the influence of floor thickness on the tensile and compression stress of the floor after the early dismantling.When the thickness is between 100 mm and 150 mm,the maximum compression stress and tensile force of the floor in various parts decreases bout 50%.(4)The most unfavorable construction load layout is conducted in the light of the support.The calculation result shows that the maximum compression stress and tensile stress increased 0.12~0.34 MPa 0.013~0.018 MPa,rising about 5%.(5)In the concrete structure design,the concentrate near the support is compression zone.After the early dismantling,the region becomes tension zone.Through the method of finite element calculation of the influence of the width of the panel here to stress early after the demolition of the floor.Panel width changes from 100 mm to 400 mm,floor in Y direction edge at the midpoint of the tensile stress and decrease the compression stress of 12% to 15%,and support at the tensile force decrease extent is only 3% to 5%.