A new dapped‐end beam to column connection is designed in this paper. Its assembly connection zone changes from inside the joint to midspan of the beam. The proposed connection can not only provide good structural integrity but also ensure that the plastic hinge moves away from the column edge. The rotational capacity of the plastic hinge determines the internal force redistribution of the joint and the energy dissipation capacity. The high‐strength bolts and steel plates are used to realize connection, further enhancing the rotation of the plastic hinge and minimizing the cast‐in‐place concrete volume. Three full‐scale exterior beam to column joints are casted and then subjected to reversal cyclic loading. The finite element (FE) analyses are carried out to compare with experimental results and study the effect of connection position on the structural behaviours. The obtained results show that the plastic hinges of all three specimens are firstly developed to a distance from the column edge, thus revealing that this kind of joint can achieve beam hinge mechanism and prevent joint shear failure. And the connection position is the most disadvantaged when coinciding with the plastic hinge zone, which would result in the excessive deformation and the early failure of the steel bar anchor system. The new type of joint shows good seismic performance during earthquake if the connection can be properly designed, and thus this kind of structural form can be applied to actual engineering structures in seismic regions.
A pounding tuned mass damper (PTMD) is introduced by making use of the energy dissipated during impact. In the proposed PTMD, a viscoelastic layer is attached to an impact limitation collar so that energy can be further consumed and transferred to heat energy. An improved numerical model to simulate pounding force is proposed and verified through experimentation. The accuracy of the proposed model was validated against a traditional Hertz-based pounding model. A comparison showed that the improved model tends to have a better prediction of the peak pounding force. A simulation was then carried out by taking the benchmark Canton Tower, which is a super-tall structure, as the host structure. The dynamic responses of uncontrolled, TMD-controlled and PTMD controlled system were simulated under wind and earthquake excitations. Unlike traditional TMDs, which are sensitive to input excitations and the mass ratio, the proposed PTMD maintains a stable level of control efficiency when the structure is excited by different earthquake records and different intensities. Particularly, more improvement can be observed when an extreme earthquake is considered. The proposed PTMD was able to achieve similar, or even better, control effectiveness with a lower mass ratio. These results demonstrate the superior adaptability of the PTMD and its applicability for protection of a building against seismic activity. A parametric study was then performed to investigate the influence of the mass ratio and the gap value on the control efficiency. A comparison of results show that better control results will be guaranteed by optimization of the gap value.
1 September 2013 in Advances in Structural Engineering
Seismic behaviors of long-span connected structures under multi-dimensional and earthquake excitation while considering wave passage effect are investigated through both numerical simulation and a shaking table test on a scaled model. It is found that seismic responses will be increased significantly if multi-dimensional earthquake excitation is considered; and wave-passage effect has diverse influence on different elements. Also special attentions should be paid to those elements near connections between the main tower and the corridor which inertial forces may change a lot when subjected to Traveling wave excitation with different apparent velocities. Moreover, the vertical acceleration responses of the corridor can be increased significantly due to wave passage effect. Therefore, it is necessary for aseismic design of long-span connected structure to take into account multi-dimensional earthquake components and multi-support earthquake excitations with different apparent velocities.
A tuned mass rocking wall (TMRW)-frame structure system is proposed to improve the energy dissipation ability of the traditional rocking wall-frame system. Based on the energy dissipation principle of the traditional tuned mass damper (TMD), a TMRW is designed with proper mass and stiffness according to the dynamic characteristic of the host structure. Firstly, considering the presence of inherent structural damping, the dynamic amplification factor of the main mass was derived from the dynamic equations of the TMRW mechanism. A practical design table was then obtained after parameter study. Secondly, by taking a six-story frame structure as an example, the dynamic time-history analysis was conducted to study TMRW’s seismic performance. The inter-story drift ratios of the TMRW-frame, the traditional rocking wall-frame, and the frame structures were compared, and the seismic responses of the controlled and uncontrolled structures were also compared. The results demonstrate that the TMRW can effectively reduce the inter-story displacement of the host structure, and the lateral deformation mode of the host structure tends to be more uniform. However, compared with the traditional rocking wall-frame system, the proposed TMRW has less ability on coordinating deformation.
A tuned mass rocking wall (TMRW) is a passive control device that combines the merits of a traditional tuned mass damper (TMD) and a traditional rocking wall (RW). TMRWs not only help avoid weak story failure of the host structure but can also be regarded as a largely tuned mass substructure in the building structure. Through the appropriate design of the frequency ratio, the host structure can dissipate much more energy under earthquake excitations. In this paper, the basic equations of motion for the mechanical model of an SDOF structure-rigid rocking wall are established, and the optimization formulas of frequency ratio and damping ratio of TMRW are derived. Through the dynamic elastoplastic analysis of a six-story TMRW-frame model, the applicability of the derived parameter optimization formulas and the effectiveness of the TMRW in seismic performance control are investigated. The results demonstrate that the TMRW can coordinate the uneven displacement angle between stories of the host structure. Additionally, the TMRW is found to possess the merit of reducing both the peak and root-mean-square (RMS) structural responses when subjected to different types of earthquake excitations.
To enhance the performance of infill walls and reduce seismic damage, this paper proposes a novel prefabricated reinforced concrete (PRC) energy-dissipating wall, forming a new recoverable energy-dissipating PRC (ED-PRC) structural system. The system features pre-set gaps on both sides and the top of the PRC wall, with flexible materials filling the gaps on the sides. The top of the PRC wall is connected to the beam through several double-conical mild steel dampers to ensure the efficient transfer of horizontal shear forces between the main frame and the PRC wall. A numerical study was employed to investigate the seismic performance and the staged yield capacity. The results show that this design achieves a yielding sequence of dampers → wall → main frame. Furthermore, during the early to mid-phases of the cyclic loading simulations, the double-conical mild steel dampers with the low yield point utilized in the ED-PRC structural system exhibited exceptional energy dissipation capabilities. Notably, the LY100 dampers accounted for up to 61.84% of the total energy dissipation, with the LY160 and LY225 dampers contributing 55.35% and 50.25%, respectively. It indicates that the proposed ED-PRC structural system significantly enhances the ductility and the energy dissipation capacity under seismic loading while substantially reducing damage to the primary structure. The use of prefabricated components facilitates modular construction, allowing for quick dismantling and replacement after an earthquake, thereby rapidly restoring the structural seismic resilience.