Residual structural capacity evaluation of steel moment‐resisting frames with dynamic‐strain‐based model updating method

Abstract

Summary This paper presents a method for evaluating the residual structural capacity of earthquake‐affected steel structures. The method first quantifies the damage severity of a beam by computing the dynamic‐strain‐based damage index. Next, the model used to analyze the structure is updated based on the damage index, to reflect the observed damage conditions. The residual structural capacity is then estimated in terms of changes in stiffness and strength, which can be applied by structural engineers, via a nonlinear static analysis of the updated model. The main contributions of this paper are in performance evaluation of the dynamic‐strain‐based damage index for seismically induced damage using a newly developed substructure testing environment, consideration of various damage patterns in composite beams, and extension of a local damage evaluation technique to a residual capacity estimation procedure by incorporating the model‐updating technique. In laboratory testing, the specimens were damaged quasi‐statically, and vibration tests were conducted as the damage proceeded. First, a bare steel beam–column connection was tested, and then a similar one with a floor slab was used for a more realistic case. The estimated residual structural capacities for these specimens were compared with the static test results. The results verified that the proposed method can provide fine estimates of the stiffness and strength deteriorations within 10% for the specimen without the floor slab and within 30% for that with the floor slab. Copyright © 2017 John Wiley & Sons, Ltd.

Review on Vibration-Based Structural Health Monitoring Techniques and Technical Codes

“…One direction to improve is to construct the baseline of structure mode shapes more accurately. Finite element (FE) model updating has been widely used for this purpose [25][26][27]. Conventional FE model updating was constructed for regenerating of baseline of frequencies and mode shapes.…”

Damage Identification of Semi-Rigid Joints in Frame Structures Based on Additional Virtual Mass Method

“…Structural damage identification based on vibration data can be mainly divided into two categories: model-based parametric methods and signal-based non-parametric methods. The model-based methods take into account the changes in structural dynamic characteristics, such as natural frequency [9], modal shape [10], frequency response function [11], and dynamic strain response [12,13], and the dynamic characteristics obtained from the measured structural responses are used to update the finite element model so that the modified model can reflect the actual structural health state. Techniques of model updating can be taken as an optimization problem to minimize the difference between the information obtained from an actual damaged structure and the information obtained from the finite element model of the structure.…”

Damage detection of steel moment frames under earthquake excitation

“…To assess the damage of beam fractures under a seismic event, a strain-based DI has been numerically and experimentally validated by Li et al 51 using a nine-story SAC structure and a 1:4 scale five-story steel structure. Suzuki et al 52 estimated the amount of damages of a bare steel beam-column connection and an identical composite beam through the identification of the dynamic-strain-based DI.…”