The structural failure under severe ground motions is primarily caused by their unreasonable seismic failure mode (SFM). This paper provides a methodology aiming at the SFM improvement of reinforced concrete frame str...The structural failure under severe ground motions is primarily caused by their unreasonable seismic failure mode (SFM). This paper provides a methodology aiming at the SFM improvement of reinforced concrete frame structure. An RC frame is modeled and three types of failure criterion are defined as the premise of SFM. Static pushover analysis is adopted to identify the SFM. The dominant failure modes and failure paths of the structure are obtained in three lateral load patterns (inverted trian- gular distribution, uniform distribution and adaptive distribution). Based on the pushover analysis, the sequential failure of components and the probability of the occurrence of plastic hinges are determined. By this, weak components of the structure are detected and herein are strengthened. The project cost of the proposed strengthening strategy increases by 2.4%. Capacity spectrum method is used to study the performance of the strengthening structure. Pushover analysis is conducted again to present the improvement of strength and ductility. Lateral drift and local response through IDA are also studied to indicate that the strengthening of some columns and beams can improve the SFM to enhance the seismic capacity of structure.展开更多
Global failure mechanism, i.e., the strong-column weak-beam mechanism, can provide higher total energy dissipation capacity with less ductility demand on components than other failure modes, and results in a more unif...Global failure mechanism, i.e., the strong-column weak-beam mechanism, can provide higher total energy dissipation capacity with less ductility demand on components than other failure modes, and results in a more uniform story drift distribution and higher resistance to earthquake loads at the system level. However, the current code-based elastic design method cannot guarantee the global failure mechanism of frame structures under severe earthquakes. In this paper, a simple, but practical design procedure is proposed to ensure the global failure mechanism of reinforced concrete(RC) frame structures by redesigning the columns using the column tree method(CTM). CTM considers the yield limit state of all beams and column bases. The code-based design is firstly carried out to determine the section information of all beams and base columns. Then, the internal force demands applied on the column tree can be derived. Lastly, the column moments, shear forces and axial forces are determined according to the free-body diagram of CTM to finish the column redesign. Two RC frame structures with 6 and 12 stories are illustrated to verify the design procedure. The analytical results demonstrate the proposed approach can realize the global failure mechanism.展开更多
基金supported by the National Major Basic Research Program of China (" 973" Project) (Grant No. 2007CB714202)the National Natural Science Foundation of China (Grant No. 90815027)
文摘The structural failure under severe ground motions is primarily caused by their unreasonable seismic failure mode (SFM). This paper provides a methodology aiming at the SFM improvement of reinforced concrete frame structure. An RC frame is modeled and three types of failure criterion are defined as the premise of SFM. Static pushover analysis is adopted to identify the SFM. The dominant failure modes and failure paths of the structure are obtained in three lateral load patterns (inverted trian- gular distribution, uniform distribution and adaptive distribution). Based on the pushover analysis, the sequential failure of components and the probability of the occurrence of plastic hinges are determined. By this, weak components of the structure are detected and herein are strengthened. The project cost of the proposed strengthening strategy increases by 2.4%. Capacity spectrum method is used to study the performance of the strengthening structure. Pushover analysis is conducted again to present the improvement of strength and ductility. Lateral drift and local response through IDA are also studied to indicate that the strengthening of some columns and beams can improve the SFM to enhance the seismic capacity of structure.
基金supported by the National Natural Science Foundation of China(Grant Nos.51261120376 and 91315301)Scholarship Award for Excellent Doctoral Student granted by Ministry of Education of China
文摘Global failure mechanism, i.e., the strong-column weak-beam mechanism, can provide higher total energy dissipation capacity with less ductility demand on components than other failure modes, and results in a more uniform story drift distribution and higher resistance to earthquake loads at the system level. However, the current code-based elastic design method cannot guarantee the global failure mechanism of frame structures under severe earthquakes. In this paper, a simple, but practical design procedure is proposed to ensure the global failure mechanism of reinforced concrete(RC) frame structures by redesigning the columns using the column tree method(CTM). CTM considers the yield limit state of all beams and column bases. The code-based design is firstly carried out to determine the section information of all beams and base columns. Then, the internal force demands applied on the column tree can be derived. Lastly, the column moments, shear forces and axial forces are determined according to the free-body diagram of CTM to finish the column redesign. Two RC frame structures with 6 and 12 stories are illustrated to verify the design procedure. The analytical results demonstrate the proposed approach can realize the global failure mechanism.
