RELIABILITY-BASED SERVICE-LIFE ASSESSMENT OF AGING CONCRETE STRUCTURES

Concrete structures may be affected by aging or changes in strength an d stiffness beyond the baseline conditions assumed for design. These c hanges may impair the safety and serviceability of the structure, and should be considered as part of the process by which a structure is ev aluated for continued future service. Methods are being developed usin g structural reliability principles to evaluate time-dependent reliabi lity of reinforced or prestressed concrete structures. These methods e nable the impact on safety and serviceability of uncertainties in load ing conditions, structural strength, and strength degradation due to a ggressive environmental stressors to be assessed qualitatively. Parame tric analyses show that the reliability is sensitive to the choice of initial component strength and strength degradation models. Less sensi tivity is found to correlate component strengths within a system. Iden tification of the critical components before performing system reliabi lity analysis is important in reducing the size of the analysis. The r ole of periodic inspection and maintenance in enabling a target reliab ility level to be met over a period of continued service also is consi dered.