“…Tong et al (2020) proposed two kinds of CPD curves, including C-CPD curves corresponding to the CSA loading history and R-CPD curves corresponding to the RSA loading history. The relationship between the plastic strain range (Δ ε p ) and CPD c under CSA loading history, which can be extracted directly from Coffin–Manson curves, is defined by the C-CPD curve.…”
Section: Cpd Curvesmentioning
confidence: 99%
“…Taking BRB-1L in BRBF-6 (Tong et al, 2020) as an example, the data points are obtained from a significant number of nonlinear dynamic loading history analyses (corresponding to Δ ε pmax and CPD c ) of BRB-1 L, as shown in Figure 4. In addition, the solid line is the fitted R-CPD curve, and the dashed line is the lower bound curve (95% confidence).Figure 4.Fitting R-CPD curve of BRB-1L.…”
Section: Cpd Curvesmentioning
confidence: 99%
“…The relationship between φ and the cumulative fatigue damage of the BRB under a single ground motion ( D 0 ) corresponding to Miner’s rule (Miner, 1945) can be obtained according to equation (8), where K is the number of ground motions that cause BRB failure. It can be observed that the φ of the BRB under an earthquake excitation is equal to the D 0 in the Miner’s rule (Tong et al, 2020)where CPD 0 is the cumulative plastic deformation of the BRB under a single ground motion.…”
Section: Cpdc Evaluationmentioning
confidence: 99%
“…Therefore, both evaluation methods are simple and easy to implement. However, when BRBs in a BRB frame are subjected to earthquake excitations, it is difficult to use N f as the life index because Δ ε p, i and the corresponding N f cannot be measured directly and need to be counted by the rainflow-counting method (Tong et al, 2020). However, the evaluation method based on R-CPD curve turns the aforementioned process into a “black box,” which is more convenient to use.…”
Section: Cpdc Evaluationmentioning
confidence: 99%
“…Based on the data analysis of the test results, Andrews et al (2009) extracted possible influencing parameters of CPD, and summarized that the CPD is significantly influenced by the maximum plastic strain (Δ ε pmax ). In addition, Tong et al (2020) proposed two types of CPD curves, including the CPD curve corresponding to constant strain amplitude (CSA) loading history (C-CPD) and the CPD curve corresponding to random strain amplitude (RSA) loading history (R-CPD). The evaluation method proposed in this paper is based on these two kinds of curves.…”
To quantitatively evaluate the low-cycle fatigue life of buckling-restrained braces (BRBs), an evaluation method for BRBs based on the combination of the CPD curves and CPD measurement meter (CMM) is established herein. The difference between two CPD curves (i.e., the CPD curves under constant strain amplitude loading history (C-CPD) and under random strain amplitude loading history (R-CPD)), and their selection criteria to evaluate the low-cycle fatigue life of BRBs are discussed. An example under the variable strain amplitude (VSA) loading history and an example under the multiple earthquakes are carried out. Finally, the CPD limit values of BRBs in the ANSI/AISC 341-10 and FEMA-450 are discussed by statistical analysis of the test results of BRBs. The analysis results show that the C-CPD curve can be used to evaluate the low-cycle fatigue life of BRBs under the VSA loading, and the R-CPD curve can be used to evaluate the low-cycle fatigue life of BRBs under the multiple earthquakes. The degree of reliability of the current CPD limit value is not enough. A CPD limit curve is recommended in this study to quantify the low-cycle fatigue performance of BRBs.
“…Tong et al (2020) proposed two kinds of CPD curves, including C-CPD curves corresponding to the CSA loading history and R-CPD curves corresponding to the RSA loading history. The relationship between the plastic strain range (Δ ε p ) and CPD c under CSA loading history, which can be extracted directly from Coffin–Manson curves, is defined by the C-CPD curve.…”
Section: Cpd Curvesmentioning
confidence: 99%
“…Taking BRB-1L in BRBF-6 (Tong et al, 2020) as an example, the data points are obtained from a significant number of nonlinear dynamic loading history analyses (corresponding to Δ ε pmax and CPD c ) of BRB-1 L, as shown in Figure 4. In addition, the solid line is the fitted R-CPD curve, and the dashed line is the lower bound curve (95% confidence).Figure 4.Fitting R-CPD curve of BRB-1L.…”
Section: Cpd Curvesmentioning
confidence: 99%
“…The relationship between φ and the cumulative fatigue damage of the BRB under a single ground motion ( D 0 ) corresponding to Miner’s rule (Miner, 1945) can be obtained according to equation (8), where K is the number of ground motions that cause BRB failure. It can be observed that the φ of the BRB under an earthquake excitation is equal to the D 0 in the Miner’s rule (Tong et al, 2020)where CPD 0 is the cumulative plastic deformation of the BRB under a single ground motion.…”
Section: Cpdc Evaluationmentioning
confidence: 99%
“…Therefore, both evaluation methods are simple and easy to implement. However, when BRBs in a BRB frame are subjected to earthquake excitations, it is difficult to use N f as the life index because Δ ε p, i and the corresponding N f cannot be measured directly and need to be counted by the rainflow-counting method (Tong et al, 2020). However, the evaluation method based on R-CPD curve turns the aforementioned process into a “black box,” which is more convenient to use.…”
Section: Cpdc Evaluationmentioning
confidence: 99%
“…Based on the data analysis of the test results, Andrews et al (2009) extracted possible influencing parameters of CPD, and summarized that the CPD is significantly influenced by the maximum plastic strain (Δ ε pmax ). In addition, Tong et al (2020) proposed two types of CPD curves, including the CPD curve corresponding to constant strain amplitude (CSA) loading history (C-CPD) and the CPD curve corresponding to random strain amplitude (RSA) loading history (R-CPD). The evaluation method proposed in this paper is based on these two kinds of curves.…”
To quantitatively evaluate the low-cycle fatigue life of buckling-restrained braces (BRBs), an evaluation method for BRBs based on the combination of the CPD curves and CPD measurement meter (CMM) is established herein. The difference between two CPD curves (i.e., the CPD curves under constant strain amplitude loading history (C-CPD) and under random strain amplitude loading history (R-CPD)), and their selection criteria to evaluate the low-cycle fatigue life of BRBs are discussed. An example under the variable strain amplitude (VSA) loading history and an example under the multiple earthquakes are carried out. Finally, the CPD limit values of BRBs in the ANSI/AISC 341-10 and FEMA-450 are discussed by statistical analysis of the test results of BRBs. The analysis results show that the C-CPD curve can be used to evaluate the low-cycle fatigue life of BRBs under the VSA loading, and the R-CPD curve can be used to evaluate the low-cycle fatigue life of BRBs under the multiple earthquakes. The degree of reliability of the current CPD limit value is not enough. A CPD limit curve is recommended in this study to quantify the low-cycle fatigue performance of BRBs.
This paper proposes a hybrid data‐driven and physics‐based simulation technique for seismic response evaluation of steel Buckling‐Restrained Braced Frames (BRBFs) considering brace fracture. Buckling‐Restrained Brace (BRB) fracture is represented by cumulative plastic deformation capacity. A dataset, consisting of 95 past BRB laboratory tests and 120 simulated BRB responses generated using the finite element method, is first developed. An Artificial Neural Network‐based (ANN) predictive model is then trained using the training dataset to estimate the cumulative plastic deformation of BRBs. The prediction capability of the ANN‐based predictive model is validated using the training dataset and an existing regression‐based predictive model. In the second part of the paper, an hybrid simulation technique combining the data‐driven model and physics‐based numerical modeling is presented to conduct the nonlinear time history analysis, followed by 1) validation against a full‐scale BRBF testing and 2) demonstration of the proposed simulation technique using a six‐story BRBF. The results confirm that the proposed predictive model can predict the BRB fracture with sufficient accuracy. Furthermore, the hybrid data‐driven physics‐based simulation technique can be used as a powerful tool for dynamic analysis of BRBFs considering BRB fracture.
In order to avoid the damage of the connection due to the overstrength of beam strength, and the alternation of the strength hierarchy in the structural system. The additional bending moment produced by the combined action of the pressure generated by the concrete compression zone and the tension generated by the reinforcements needs to be reduced. A novel precast concrete beam-column connection is proposed herein. In the proposed connection, the precast beam is laid on a steel corbel embedded in the precast column. A novel replaceable energydissipation connector (REDC) is placed at the bottom of the steel corbel, which ensures that it is in the same horizontal position aligned with the longitudinal reinforcement at the bottom of the connection. In addition, there is a narrow vertical slot adjacent to the column face. The total yield capacity of the top reinforcement is larger than that of the bottom REDC energy-dissipation connector. Theory study focused on the structural features and mechanical mechanism of this novel precast connection. Three low-cycle quasi-static loading tests were carried out on a single full-2 scaled specimen by replacing three REDCs with different sizes. The cracking pattern of this novel precast connection, and the effects of different parameters of the REDCs on the energy-dissipation capacity and load capacity of the connections were discussed. By performing a finite-element simulation, a method for reducing the additional bending moment and keeping the top reinforcements always in elastic was developed. In addition, the relevant design suggestions were provided. The conclusion shows that the seismic performance of this novel precast concrete beamcolumn connection is excellent. The positive and negative bending moments of novel precast concrete beam-column connection both reduce the additional bending moment. In view of this, the bending moment of the novel connection is a controllable variable.
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