Evaluation of Wind Load Factors of RC Columns for Wind Load-Governed Limit State in Reliability-Based Design Code


Ji Hyeon Kim, Chul Hwan Yoo, and Hae Sung Lee



 This paper presents a general approach for evaluating wind load factors based on measured wind data for RC columns. Reliability analyses were carried out by an advanced first-order second-moment reliability method to investigate the wind load?governed limit state for the RC pylons of five cable-supported bridges in Korea. The axial force-bending moment (P-M) interaction diagrams of the pylons define the limit-state function. Load and strength parameters were considered random variables in the reliability analysis. The statistical parameters of wind load were determined by Monte Carlo simulation. Based on the results of the reliability analysis, dead load factors were set to the bias factors of dead load components, and a P?M interaction diagram drawn by the mean values of the strength parameters was used to define a design equation. The failure point of the wind load was obtained by equating the nonexceedance probability at the failure point of wind load to the probability of safety corresponding to a given reliability index. An analytical form of the wind load factor was derived in terms of the statistical parameters of wind load and the target reliability index. The wind load factor was adjusted to be used with the dead load factors and the resistance factor specified in a reliability-based design code. Validity of the proposed load factors was verified through a reliability assessment of the pylon sections of the five bridges. It is shown that the proposed load factors secure the target reliability levels within a 2% error.

KEY WORDS : Wind load factor, Calibration, Probability of failure, Target reliability index, RC column, Wind pressure

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