Probabilistic Modeling of Structural Forces

Since forces acting on structures fluctuate widely with time and space during the lifetime of a structure, variations of the forces should be considered by probability distributions. Probabilistic definition of forces is expressed by random field variables including stochastic parameters. Structural forces are simulated by adopting Normal and Gamma probability distribution functions. The basic model given by JCSS (Joint Committee on Structural Safety) code principles is used as model to take into account the variations. In the simulation of the live loads comprised of sustained and intermittent loads, time intervals are assumed to follow a Poisson process and their distributions are defined by exponential distributions. The simulated loads are evaluated in terms of percentiles, correlation effects, reduction factors and extreme values. Results are compared with those of deterministic model as well. It has been observed that probabilistic model is more realistic and the results can be used in the calculation of specific fractiles like load and resistance factor design

Field validation of models for predicting lateral form pressure exerted by SCC

International audienceOne obstacle to increased use of self-consolidating concrete (SCC) in cast-in-place applications is a fear of high, lateral formwork pressure. The literature has repeatedly shown that pressures far lower than hydrostatic can be obtained, but still a widespread concern of high pressure exists. Several models for predicting the lateral pressure when casting SCC have been developed. A number of experts representing these models gathered in Stockholm, Sweden to carry out a field evaluation. Eight instrumented wall elements with various geometries were cast with SCC using different mix designs as well as various casting rates. Pressure transducers were used to determine the lateral pressure. All necessary parameters for the respective models were characterized simultaneously by the participants using samples taken from the same batch. Results show a wide range of form pressures, and the evaluation of the ten included models reveals that all of them predict the lateral form pressure satisfactorily