- Author
- Bizri, H.
- Title
- Structural Capacity of Reinforced Concrete Columns Subjected to Fire Induced Thermal Gradients.
- Coporate
- California Univ., Berkeley
- Sponsor
- National Science Foundation, Washington, DC
- Report
- UC SESM 73-1, Janaury 1973, 205 p.
- Distribution
- Available from National Technical Information Service
- Contract
- NSF-GRANT-GI-43
- Keywords
- reinforced concretes | columns | gradients | high temperature | thermal analysis | case histories | steels | mathematical models | temperature distribution | concrete columns
- Identifiers
- nonlinear structural analysis; structural behavior
- Abstract
- Based on prescribed fire time-temperature conditions the response of planar reinforced concrete frame structures was obtained at selected time intervals in terms of temperature distributions, forces, moments and displacements. Temperature dependent thermal and mechanical material properties as well as creep, shrinkage, tensile cracking and crushing were considered in this analysis. A mathematical model was formulated in three stages. First a study was made of the effect of high temperatures on the thermal as well as mechanical properties of both concrete and steel, and appropriate mathematical expressions for material behavior were developed in the form of envelopes. The second stage consisted of predicting the temperature distribution at different times throughout the structure. For this purpose a finite element solution to the transient heat flow equation was developed. The third stage consisted in examining the structural behavior. For this purpose a nonlinear method of analysis was developed using a step-by-step time-load incremental technique. In each step of the structural analysis a displacement method of analysis was used, in which the reinforced concrete structure was geometrically discretized and was assumed to be composed of members; each member was divided into segments; and each segment cross-section was discretized into slies or depth increments. The behavior was described in terms of forces, stresses, strains and displacements. Applications of the mathematical model were demonstrated by a parametric study on reinforced concrete columns. Although the model is capable of analyzing beams as well as frames, the examples were limited to the column study.