An expert-opinion survey of structural construction details in existing buildings

The performance assessment of structures is subjected to various sources of uncertainties. One of the most challenging aspects of the seismic assessment of existing buildings is the characterization of structural modeling uncertainties since it measures the incomplete knowledge of the structural properties in as-built conditions. It is possible to distinguish between two different sources of structural modeling uncertainties in the assessment of existing buildings: uncertainty in the mechanical properties of materials used in construction and the uncertainty in construction details that affect the component capacities. It is important to take into account the uncertainties in the construction details since the variations in structural detailing parameters (a.k.a. structural defects) can be quite significant; to the extent that they may change the eventual structural collapse mechanism. The focus of this work is to provide a basis for the characterization of the uncertainties related to the construction details attributed to the as-built conditions of the structure. This is achieved by interpreting and quantifying the common pool of knowledge created by professional experience into prior probability distributions. These prior probability distributions can be used in a Bayesian framework in order to take into account the uncertainties in the construction details before implementing the data provided by the tests and inspections. An expert-opinion survey addressed to practicing engineers has been conducted. The preliminary results obtained by interviewing a group of practicing structural engineers are presented. It is demonstrated how the results of such survey can be processed in order to construct prior probability distributions for selected structural detailing parameters.