The Research On Durability Assessment Method Of Corroded Reinforced Concrete Structural Members

Reinforced concrete structure is a structure form that is most widely applied in engineering. Since it is found that the reinforced concrete structure is demolished prematurely because of the corrosion of reinforcement, it becomes a focus to which civil engineering field pays attention generally. So it is very practically and economically valuable to evaluate the durability of a vast number of concrete structures in service in China.Corroded reinforced concrete members are the research object in this dissertation. Based on studying mechanics property and destroy pattern of corrosion members, and combined with recent national and international achievements in reinforcement corroding durability research, durability assessment of corroding reinforcement concrete member is studied through combining quality analysis with quantity calculation. Furthermore, assessment level and grade are given. The main works of this dissertation are as follows:1) The most recent durability research of reinforcement corrosion is generalized.2) Each calculation method of member assessment item (including concrete cover cracking because of corrosion, concrete cover cracking limitation, chloride-ion eroding, deformation and bearing capacity) is introduced. Then the grade of corroding reinforcement concrete member is given. And the corroded reinforced concrete member durability assessment method considering manifold influence factors is primarily established. 3) Corroded reinforced concrete basic member (such as beams, slabs and columns) durability experiments have been carried out to study the influence of corrosion on the mechanics property and destroy pattern of it. Then influence factors of the structure member's bearing and ductility is studied.A computer software--Expert System for the Durability Assessment of In-Serving Reinforced Concrete Structures (ESDAR-1 in simple)--has been programmed. The ESDAR-1 is based on the member durability synthesis assessment method. In this dissertation, using corrosion reinforcement measuring data of experiment member and steelworks outdoor trestle column in Shangming City, Fujian province, the ESDAR-1 is applied to assess corroded member's durability. Through analyzing durability assessment results4) of corroded members, rationality and feasibility of the durability assessment method are validated.The conclusions obtained in this dissertation are as follows: Firstly, although member durability assessment relate to many uncertain and unsure factors, degraded mode which is established according to corrosion reinforce character of microcosmic mechanism and macro phenomenon can assess corrosion reinforcement's durability grade and estimate member's residual life comparative exactly. Secondly, member's durability grade associates with expected service life closely. Member's durability grade descends with expected service life increasing. Thirdly, in engineering assessment, service durability often depresses to a level lower than that of working requirement earlier than safety durability. So we should pay attention to member service durability as well as member safety durability, especially when some structures need good appearance. Finally, reinforcement corrosion is a primary factor that influences member durability. Especially after the cover cracks because of corrosion, it is necessary to make repair efforts to improve member durability in order to avoiding unnecessary loss...