Cyclic performance of precast hybrid frame-rocking wall structures | |
| Author | Ekkachai Yooprasertchai |
| Call Number | AIT Diss. no.ST-16-03 |
| Subject(s) | Precast concrete construction Building materials |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ST-16-03 |
| Abstract | Recently, jointed precast structures—novel precast concrete (PC) structures—have emerged as a promising alternative to conventional monolithic emulation structures. In these structures, the connections are not designed to be rigid and strong; instead, the connecting interfaces between PC members are designed to open under high loading and close completely under unloading. This allows the structure to sway laterally to a considerable extent, without causing any cracks or other visible damage to the PC members. Thus, the structure is able to return to its original configuration—an ability commonly termed “self-centering.” This dissertation examined the applicability of precast hybrid moment-resisting frames (PHMRFs) combined with PC rocking walls (PCRWs) to resist strong ground shaking in buildings. This hybrid system’s performance was investigated through experimental and analytical studies. The frame–wall dual system provided the advantages of each type of structure, in which the rocking walls typically provided suitable lateral load resistance, as well as better limitation of displacement in mid- to high-rise buildings. The combination with PHMRFs provided a source of energy dissipation via the formation of nonlinear hinges at the ends of beams and columns located immediately above the foundations. The study consisted of two phases. The first phase independently conducted a series of quasi-static reversed cyclic loading tests and commonly adopted fiber models using the Ruaumoko computer program for the frame and wall subassemblages, in order to understand the fundamental behavior of each structural component. The tested specimens consist of four frame subassemblages and three wall subassemblages. After determining the behavior of the independent subassemblages, the second phase coupled the frame and wall subassemblages to investigate their interplay through a quasi-static reversed cyclic loading test and fiber model. For the PHMRF subassemblages, this study tested two interior beam–column connections (with and without a slab system), one exterior beam–column connection, and one column– foundation connection. The tested models demonstrated excellent seismic performance. They had better ductility and were able to sway up to high levels of story drift ratios (SDRs) (up to an SDR of 6%) with minimal damage. Hysteretic damping energy dissipation was primarily achieved through the yielding of mild steel reinforcement installed at the beam–column and column–foundation connections. In addition, the hybrid frame subassemblages could return to the original position upon unloading because of the use of post-tensioned (PT) steels. The force–displacement verifications between the experiment and commonly adopted fiber model were in good agreement. The capacity design concept used in the design process was proven through both experimental and analytical programs to effectively limit the nonlinear responses in predetermined locations. For the wall subassemblages, a buckling restrained brace (BRB) was proposed to improve the energy dissipation of the PCRW. For this purpose, a series of quasi-static reversed cyclic loading tests was conducted for the BRB, PCRW subassemblage, and combined PCRW–BRB system. The results indicated that the stable elasto-plastic BRB supplied vibration energy to the nonlinear elastic responses of the PCRW. The test units showed excellent seismic performance, and attained large lateral drift ratios—up to drifts of 2.5% for the walls. The nonlinear deformation was located only at the wall bases and BRBs. The fiber model concepts developed for the PHMRF were applied to the walls. The fiber model iv analysis of the conventional hybrid wall (the wall incorporated with mild steels at its base as energy dissipaters) was also conducted and validated with the previous research. The study confirmed that either BRBs or mild steels can be used effectively as energy dissipaters in PCRWs. In the final phase, the PHMRF coupled to the PCRW was investigated through experimental and analytical studies. The force–deformation responses of the system showed satisfactory ductile stable flag-shaped hysteretic loops from small to large lateral drift levels, up to 2.34%. Although the PHMRF was able to deform up to high ductility, when combined with the rocking wall, it required less ductility than the wall. The wall had relatively high ductility demand (as high as ductility of 23.4), compared to the frame, which required ductility of 7.8, corresponding to ductility of 13.8 for the combined system. The fiber model also aligned well with the measured data. The jointed precast structural system investigated in this study offers an alternative structural system to achieve seismic resistance in a building. Each structural system investigated in this study demonstrated good seismic performance. Thus, engineers can appropriately select a system depending on the building configuration and client needs. |
| Year | 2016 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ST-16-03 |
| Type | Dissertation |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Pennung Warnitchai; |
| Examination Committee(s) | Anwar, Naveed ;Punchet Thammarak ;Amorn Pimanmas; |
| Scholarship Donor(s) | Royal Thai Government ;AIT Fellowship; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2016 |