Probabilistic evaluation of safety of buildings during construction

The safety of steel buildings, constructed by the tier method, is evaluated. Variations of reliability during construction for steel frames with rigid and flexible designs are examined. At each stage of construction, the potential modes of failure are identified and formulated for reliability analysis. The principal loading of concern is the maximum wind load over the critical stages of construction. Uncertainties associated with the properties of the structure at each stage of construction and the wind environment parameters are included in the formulation. The dynamic effect of wind on an incomplete frame is evaluated using elements of random vibration. In addition to the construction procedure and type of structural design, variations of reliability during construction due to changes in the planning and scheduling of the project are also examined. The reliability of a ten-story steel frame building, built by a common combination of crew and equipment, is examined in detail. A number of conclusions were derived which may be pertinent to the reduction of risk in construction.