Research On Temperature Crack Control Of Steel Plate Concrete Composite Shear Wall At Early-construction Stage

Steel plate concrete composite shear wall structure is typically used in superhigh-rise buildings as well as large-span buildings because of its high strength, hugelateral stiffness and good ductility. In order to achieving high strength and beingpumped to a certainly high level, etc, steel plate concrete composite shear wall (SPRCWfor short) is commonly used with high performance concrete (HPC for short) which hasthe properties of high flowability and self-compacting. However HPC consists of suchlarge amount of cement, which would release hydration heat and cause temperaturerising, that it shrinks severely at the early stage of construction. As a result, stressesinside SPRCW will occur to develop into cracks when the shrinkage of HPC isrestricted by steel plate and studs, and enventually it woud weaken the durability of thewhole structure. So, for the purpose of relieving cracking degrees, it is necessary to findways to control temperature cracks of SPRCW at early construction stage and to guidthe design and construction of practical projects.As the internal source of temperature, concrete hydration heat itself varies overtime. Additionally, concrete will release heat into atmosphere in a form of thermalconvection after being poured, and the speed from the inside to the outerside differsfrom each other. All of these bring about temperature gradient and stresses. So, at theearly stage of construction, SPRCW’s stress field caused by temperature as a result ofhydration heat is a complex physical field which can be affected by both space and time,and their relevant factors are so hard to confirm that concrete is often assumed to beisotropous when analysising the effect of hydration heat to temperature.High development of computer not only promots mathematical analysistechnology but also springs up many huge commonly used finite-element softwares, andit provides an effective tool for modeling and analysising temperature cracks of SPRCWat early construction stage. In this paper, ABAQUS software is used to study SPRCW’stemperature cracks at early construction age. First of all, three models are set up toresearch the relationship between hydration heat and temperature, they are “single layerof SPRCW model”,“under the action of circulating water model” and “three layerspoured one by one model”, respectively. Secondly, on the basis of the relationshipbetween hydration heat and temperature, anather model is built up to analysistemperature stress and temperature crack of SPRCW. In the end, the following conclusions are summarized:①Under the influence of both hydration heat and atmosphere at the early stageof construction, SPRCW’s temperature rises quickly at first, and then it coolsdown slowly. Meanwhile, in the whole process, the temperature of concretefrom the inside to the outside is different from each other, reflecting that theinternal temperature is higher than the external temperature. However, withconstruction time going, the internal and external temperature of concretecomes to be the same as atmosphere temperature.②SPRCW’s highest temperature caused by hydration heat can be lowered downby setting up cooling-water pipe inside. And moreover, cooling-water pipe canalso make temperature distribution much more uniform. So, it is an effectiveway to control the temperature cracks of SPRCW at early construction stageby installing cooling-water pipe during construction.③It will influence each other when SPRCW is poured layer by layer, whichmeans that the hydration heat from the upper layer will make the temperatureof the lower layer rise again and it is likely to cause cracks where the upperlayer and the lower layer connect. So measures should be taken to strengthenthe connection.④Studs and steel plates in SPRCW restrain the early shrinkage of concrete, andstuds can have a bad effect of seducing concrete ro crack.⑤In a certain range, the space of studs is smaller, the stress in SPRCW is moreuniform and the cracks are fewer. So, it is better to design space of studssmaller provided that it matches construction condition.