The Twin Towers Oblique Lats Bridge Pile Group Mass Concrete Construction Temperature Control Study

During curing period integrally-cast, mass concrete structure has two main deformations, i.e. temperature shrinkage deformation and hydration shrinkage deformation. Under the constraint, it has tension stress in the interior and on the surface of the structure. It would get structure cracks if the tension stress is higher than the tensile strength of concrete at the referential age. So we must strictly control the temperature to avoid excessive temperature stress and the occurrence of the cracks or to reduce the cracks. For the purpose of the temperature control during the mass concrete construction of the No. 40 and 41 of the main tower pier cap on long-men yellow river bridge, the author has done a lot in Concrete mix design and temperature control calculation, provided some advice for temperature control and adjustment, monitored temperature and analyzed the results. The following are some detailed works.1. Concrete mix design. Five mix designs are strongly recommended after a great deal of trials in the raw materials and the adjustment of mix design. Department of the project adopted the most exact design for them. Project construction site in accordance with the actual situation in which a select mix of Ymk4.2. Temperature control calculation. Considering the impact of construction and temperature control, it simulated 3-D transient temperature field by finite element method. With the analysis of the results, temperature-field distributing orderliness in the construction is figured out so as to evaluate the construction quality in validity and check the effect of temperature-controlling.3. Temperature control methods and its adjustment. The following five aspects are discussed to have a better control of temperature and its adjustment, such as, concrete mix design, concrete placement temperature control, cooling water pipes settings and adjustment, the conservation of temperature and humidity, and time limit modification.4. Temperature control monitor and analysis of the results. Temperature control monitor included temperature monitor and strain monitor. Some reasonable conclusions for better temperature control are provided on the basis of analyzing a great deal of effective measured data throughout the monitor.