Theoretical And Experimental Research On Construction Technology Optimization Of T-type Continuous Rigid Frame Bridge In Closure Section

Prestressed concrete continuous rigid frame Bridges are widely used in bridge engineering because of their advantages such as strong spanning ability,large stiffness,convenient construction and good driving comfort.With the continuous deepening of bridge design theory,continuous improvement of construction equipment functions,continuous innovation of construction methods and continuous emergence of high-performance materials,continuous rigid frame bridge is more and more suitable for bridge engineering with long span and wide body.Closed construction as the main control factors in the continuous rigid frame bridge cantilever casting method,is to determine the key link in the process of bridge construction quality and construction progress control,construction control does not reach the designated position can cause technical defects,resulting in the quality of the Bridges,so studying the closed period of the construction technology of long span continuous rigid frame Bridges at home and abroad scholars and engineers focus.This article is based on a three span continuous rigid frame bridge construction progress control requirements,through the analysis of the closed period of construction scheme and fold in the early period of concrete material properties(compressive strength and elastic modulus)and put forward a kind of optimization solutions to bridge construction process,its innovative point is that by improving the construction technology for prestressed rigid-frame fold section,including prestressed tensioning order,tensioning tendon quantity every time,grouting method,etc,the scheme make breakthrough in key technology of construction,control each link of the construction period,complete the closed period of time limit for a project of constraints,so as to realize the target of bridge construction control.In order to verify the feasibility and advancement of the optimized construction scheme,the stress and deformation of the whole bridge after improving the construction technology were simulated and analyzed in the construction stage and operation stage.This paper consists of five chapters and mainly carries out the following research work:(1)Design of construction process optimization scheme of closure section.According to the design of a rigid frame bridge has been according to the characteristics of the prestressed technology and relying on the advanced equipment for technological transformation,the construction units to meet the time limit for a project goals and objectives,research all kinds of feasible solution and co MPare the characteristics of each scheme,determine the compressed folded section of prestressed tensioning construction and to improve the performance of early age concrete joint scheme.After the implementation of this optimization scheme,the construction period of a single bridge can be shortened by 54 days,and finally the opening time of this rigid frame bridge can be implemented before the original construction period(before the end of November of the construction year).(2)An experimental study on early age performance enhancement of concrete was carried out.In order to ensure that the compressive strength and elastic modulus of the concrete in the closed section in the early age meet the requirements of tensioning prestress,three kinds of concrete mix ratios of single silica powder,single silica fiber and compound silica fiber were selected and tested.Results show that the single way of doped silicon powder concrete early age can not only effectively enhance the compressive strength and elastic modulus,and on the economic advantages,construction aspects: along with the increase of the dosage of silicon powder concrete in early age strength and elastic modulus has large improvement,basically at the ages of 4 d in blank control group compressive strength of concrete 7 d age.(3)The demonstration of the construction technology optimization scheme of the closure section is completed.Midas/Civil software was used to simulate and analyze the prestress optimization scheme by finite element method.The results show that most of the Bridges in the construction stage are in the state of compressive stress,and the tensile stress is small when under tension,which conforms to the limit requirements of tensile stress in the code,thus confirming the construction technology.The continuous rigid frame bridge project based on this paper can achieve the purpose of shortening the construction period safely and effectively after adopting the closure section construction technology optimization scheme.