Interaction Analysis And Actual Measurement Of Construction Of Different Thickness Concrete Floor

In recent years,due to the lack of land resources and the development of urban construction,high-rise buildings have gradually increased.Mass concrete foundation slabs are a common form of high-rise buildings.For the same high-rise building,the foundation slabs have different functional zones.There are often differences in the thickness of concrete.The temperature stress fields of adjacent large-volume concrete foundation slabs of different thicknesses are different and will affect each other during construction.The study of their mutual influence laws needs to be improved.This paper takes a high-rise building in Jinan as the research background and uses finite element software to carry out numerical simulation analysis of its temperature stress field.The main contents and research results are as follows:(1)Analyze and summarize the research status of large-scale concrete temperature stress field at home and abroad,and systematically introduce the basic theory of concrete temperature field and temperature stress,including the heat conduction equation of concrete,boundary value conditions,finite element calculation theory of temperature field and temperature stress theory,it lays a theoretical foundation for the study of the mutual influence of the temperature stress field of the adjacent mass concrete foundation slabs with different thicknesses.(2)Use finite element software to establish four types of concrete foundation slab combination models with different thicknesses.According to the site construction plan,determine the boundary value conditions,the cement hydration heat release law,and the change law of the elastic modulus.The field is numerically simulated to obtain the interaction between adjacent large-scale concrete foundation slabs of different thicknesses: 1)The adjacent large-volume concrete foundation slabs with different thicknesses have a great influence on each other at the junction.2)The farther the horizontal distance from the boundary of the concrete base plate of different thickness is,the smaller the mutual influence is.3)The thicker the adjacent base plate,the greater the mutual influence.4)In the initial stage of concrete placement,the part with higher tensile stress value appears in the lower middle position of the concrete floor.The concrete surface has a higher tensile stress valuethan the internal structure.With the completion of the concrete pouring,the thermal stress in the combined model of concrete slabs with different thicknesses changed from tensile stress to compressive stress.The tensile stress values at the upper surface of the concrete slab and at the junctions of the concrete slabs with different thicknesses are larger,and the junctions of the foundations with different thicknesses are sharp angle,there is a phenomenon of stress concentration.(3)The real-time temperature monitoring of the entire construction and pouring process of a large concrete foundation slab in an actual project.Temperature monitoring data shows that: 1)The mass concrete at the construction site is layered.The maximum temperature of the concrete generally appears within 2 to 5 days after the completion of the concrete,and the heating rate of the concrete is much higher than the cooling rate of the later concrete.2)Due to the existence of adjacent concrete foundation slabs of different thicknesses,the temperature measurement point 1 is the combination model 2.The maximum temperature position inside the 7 m thick concrete foundation slab changed.The maximum temperature does not appear at the middle depth of the concrete slab,but appeared at the depth of D = 2.0 m.(4)Comparing the actual measurement results with the theoretical simulation results,the change laws are basically the same.Because there are many influencing factors in the actual construction process,the finite element numerical simulation cannot be completely the same as the actual construction environment,and the values are different.In the actual construction process,numerical simulation should be combined with measured data in order to take corresponding temperature control measures to ensure the safety of the structure.(5)Based on the previous study on the interaction between the thermal stress fields of the adjacent mass concrete foundation slabs with different thicknesses,two new combined models were added to further analyze and summarize the interaction laws of the temperature fields.