A Simulated Prediction On The Remaining Life Of In-service Reinforced Concrete Structures In Cold Areas

Since reinforced concrete structures in cold northern areas are affected by randomearthquake, natural aging, and a number of durability factors such as concretecarbonation, the erosion of chloride ions, steel corrosion, and the freeze-thaw cycle,this paper aims to study the remaining life of in-service reinforced concrete structuresbased on computer simulation. The intensity of an earthquake is simulated by adoptingtime steps method and the sequence of events through the simulation of artificialseismic waves, and thus the correspondent artificial seismic waves are simulated withthe standard response spectrum as the target spectrum. An analysis on random dynamicelastic response of reinforced concrete structures is done by adopting the stiffnessdegradation principle with consideration to the cumulative damage of structures underan earthquake. The damage to the safety of the structures is determined with the failurecriteria of both deformation and energy. Meanwhile, the coupling effect of concretecarbonation, steel erosion and freeze-thaw cycle on the durability of structure are alsoconsidered. The damage to the durability of the structure is determined with damageidentification technology and an economic maintenance decision is made by adoptingbenefit-cost analysis method. The structure is confirmed to be invalid, i.e. it is in a stateof severe damage or collapse, after many times of simulations until the earthquake ordurability damage reaches the limit. Thus a sample value of the life of a structure isobtained after the simulations, from which the life distribution, mean and variance ofthe engineering structure can be deduced to further reveal the relationship between thelife of a structure and random earthquake or durability. “Fast-freezing method” has been adopted in this paper for the study of thefreeze-thaw cycle and antifreezing tests have been done on concrete with differentwater-cement ratios. The influence of freezing resistance of concrete on its durability isevaluated by two indexes: mass loss and the relative dynamic elasticity modulus, andthe life prediction model of concrete durability of the freeze-thaw cycle has beenestablished.Through the mechanical tests on eroded reinforced bars and load tests onlarge-scale roof boarding of in-service non-prestressed reinforced concrete structures,this paper has studied the carrying capacity, deformability and test failurecharacteristics of eroded reinforced bars and damaged or aged components, and putsforward the influences of durable damages such as the concrete damage and coverdropping on the carrying capacity of components.This paper has adopted computer simulation and studied the remaining life of anin-service reinforced concrete structure by taking account of its safety, durability andcost-effectiveness. Besides, an in-service single-deck industrial factory building in thecold northern area has been used as an example for verification. The conclusion isreasonable and reliable. This paper has offered a new insight and method on the studyof the prediction of the remaining life of in-service reinforced concrete structures andhas a theoretical significance and practical value.