Super-long Concrete Structure Temperature Stress Analysis

With the increasing of China's comprehensive national power and the accelerating of the pace of modernization,the ultra-high,ultra-long structure becomes the main direction of the development for future urbanization whether in the highly developed cities where the business is the most active,such as Beijing,Shanghai,Guangzhou,Hangzhou,Shenzhen,or the large,super large cities emerged due to the project “China Western development”.Functional requirement is no longer the only criteria for buildings and constructions.The requirement of an artistic appearance is also growing.Many ultra-long structure needs to be designed as seamless structure.Therefore it is particularly important to solve the problem of temperature stress.This paper reviewed the study of temperature stress in reinforced concrete super-long structure and illustrates the current status of the research in this area.Based on the real case,“Xi 'an 330 indoor isolation transformer substation building(plane size96m×42m)”,isolation model and non-isolation model are set up respectively.The isolation models contain post-cast strip model and expansion strengthening belt model.Therefore totally 4 models are established.This paper focused on the influence of temperature effect on building structures in long time running and the temperature changing by seasonal variation.The influence of temperature change is not the only element needs to be considered when analyzing the temperature stress of structure,others factors like the drying shrinkage of the concretes is also critical.During calculation,drying shrinkage of the concretes should be equivalently transferred to the corresponding temperature stress.The shrinkage of the concrete is one of the major causes of super-long structure crack.By calculating the dry shrinkage deformation value,the shrinkage stress is obtained,combined with shrinkage equivalent temperature difference and seasonal temperature difference,the finite element analysis software SAP2000 is applied for the analysis of the temperature stress of super-long structure,and the influence of the post-pouring joint closed temperature on the whole structure temperature stress is discussed for future design and construction of super long structure.Major conclusions are listed below:1.After the analytic of the data for four models,it is easy to do the comparison in regard of reducing temperature stress: the most effective one is the isolation model with isolation layer,its frame column shear force and bending moment is reduced by 98.5% compared with the models without taking any measures of isolation;the post-cast strip model is in second order,its frame column shear force and bending moment is reduced by 38.8% compared with the models without taking any measures of isolation;the expansion strengthening belt model is in the third order.its frame column shear force and bending moment is reduced by 36.6% compared with the models without taking any measures of isolation.2.With the effect of temperature,for Super-long concrete structure,the frame beam axial force is the biggest around the fixed deformation point and the internal stress and deformation of the pillars on side-area or cross-area are the biggest.A large number of temperature cracks will appear if the temperature stress was not reduced appropriately and hence affect the structural safety.3.This paper uses finite element analysis method to respectively compare six crack control methods.Among them,the post-cast strip model and expansion strengthening belt model are proved to be the effective methods.The internal stress in frame beams and columns is release effectively in both of the two models mentioned above.4.Without affecting the construction period,the post-poured strip should be finished at low temperature,the lower the better.5.Without taking any measures of vibration isolation at the ends of the model about the displacement of 8.0883 mm and 7.7467 mm respectively,setting post-cast joints on both ends of the vibration isolation model about its displacement is 6.1513 mm and 4.3201 mm respectively,set up the vibration isolation model of expansion reinforcing band around the ends of displacement is 5.975 mm and 4.1564 mm respectively,effectively reduce the isolation bearings on both ends of displacement,effectively solve the ends bearing lateral bring people visual sense of insecurity.