Probability of failure and risk using a concrete layer as the second barrier to water-endangering fluids

摘要

In Germany Concrete floors on ground are not subject to the design code DIN 1045, which usually demands a minimum steel part in the concrete, which is connected to extra costs. If concrete floors as second barrier for containment of water-endangering substances could be used, a financial advantage could be gained compared to other solutions (steel, plastic), because concrete is a cheap building material. The question is, whether or not concrete is safe. Concrete can fail in different ways, such as cracking. The important types of failure have been investigated. Using First Order Reliability Method (FORM), SORM and Importance Sampling Monte Carlo Simulation, the probability of failure can be calculated. Additional, if the probability of occurrence of failure of the first barrier is known, an overall probability of failure can be calculated. Depending on the toxicity of the fluid, an risk is evaluated. That means for example, that the design of the failure of the concrete floor depends on the failure of the first barrier as well as on the toxicity of the fluid. Calculations on the probability of failure of concrete layers used as second barrier have been done. At the end the results are compared with acceptable risks and costs.