First-order Reliability Method Algorithm Research Articles

Effect of 2D spatial variability on slope reliability: A simplified FORM analysis

To meet the high demand for reliability based design of slopes, we present in this paper a simplified HLRF (Hasofer–Lind–Rackwitz–Fiessler) iterative algorithm for first-order reliability method (FORM). It is simply formulated in x-space and requires neither transformation of correlated random variables nor optimization tools. The solution can be easily improved by iteratively adjusting the step length. The algorithm is particularly useful to practicing engineers for geotechnical reliability analysis where standalone (deterministic) numerical packages are used. Based on the proposed algorithm and through direct perturbation analysis of random variables, we conducted a case study of earth slope reliability with complete consideration of soil uncertainty and spatial variability.

Application of reliability theory to in-service monitoring and maintenance of parking garages

Reliability, defined as the probability of survival in a given period of time, forms the basis of most design codes. In this work, the use of reliability concepts to make informed decisions regarding in-service monitoring and maintenance is demonstrated. Parking garages are used as an example application. The degradation of the driving surface, as defined by the percentage of floor surface delaminated, was used to describe the deterioration process. The delamination is related to corrosion of the reinforcing steel accelerated by Cl− ions deposited in the concrete lattice from deicing salt laden vehicles. The time at which deterioration commences and the rate at which it proceeds are related to the depth of cover to the top level of the reinforcing steel, the water-to-cement ratio of the concrete, the concentration of Cl− ion in the deicing salt mixture, the treatments used to prevent Cl− ion attack, the crack size, and the garage temperature. A limit-state function relating to the degree of delamination to the garage age and other influencing parameters was developed and used in a first-order reliability method algorithm to evaluate repair intervals and treatments such as polymer impregnation, vacuum treatments, boiled linseed oil, and absorptive form liners. Considerable savings in maintenance costs may be achieved through optimum scheduling and choice of garage surface treatment. Key words: reliability, maintenance, parking garages, monitoring, repair, inspection.