Prediction of Injuries to Building Occupants From Column Failure and Progressive Collapse With the Bicads Computer Program

Abstract

This paper describes the methods used to predict column failure, progressive collapse, and building occupant injuries from progressive collapse in the BICADS (Building Injury Calculator And DatabaseS) computer program. The BICADS program, which was developed recently by Baker Engineering and Risk Consultants, Inc. (BakerRisk) for the U.S. Department of Defense, is an approximate methodology that estimates injuries to occupants from structural and nonstructural components in a wide variety of bla st-loaded buildings. The percentages of occupants with each of four different injury levels are calculated from blast-damaged walls, columns, roofs, floor systems, windows, and interior nonstructural components that are part of sixteen different convention al building types or a user input building type. Simplified or detailed input options defining the building structural components are available with photographs, explanatory text boxes, and several help files to aid user input. This paper describes the methodology used in BICADS to predict column failure and progressive collapse for typical concrete and steel framed buildings. The simplified, fast running methodology is based on pressure-impulse diagrams developed from theoretical equations for single-degree-of-freedom response and on limited data from U.S. government tests and terrorist bombs on full -scale columns with close-in explosive loads. Shear response is assumed to control concrete column failure. Anchor bolt response is assumed to control steel column failure if there is a shear plane through the bolts. Flexural response is assumed to control if the column baseplate is buried in the floor slab or the column is continuous into a basement. Column failure causes progressive collapse if the column spacing is large enough or if the column is a corner column. All building occupants within the tributary building area subject to progressive collapse are assumed to have the highest BICADS injury level, which primarily includes fatalities. This is consistent with injury data from the Oklahoma City bombing.