Post-Tensioned Earthquake Damage Resistant Technologies for Accelerated Bridge Construction
Thesis DisciplineCivil Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Over the last few decades, Accelerated Bridge Construction (ABC) has been developed to answer the growing number of societal needs, as well as advancing the bridge practice. ABC offers faster bridge construction through prefabrication of the bridge substructure and superstructure elements in a factory, and the subsequent on-site assembly of the elements. In countries such as the United States, many of the state Departments of Transportation (DOTs) have developed ABC according to their own societal needs. There have been many applications of ABC in the United States, primarily in Texas, Utah, New Jersey, Florida, and Washington. However, application of ABC in regions with moderate-to-high seismicity requires in depth development, detailing consideration, experimental investigation, and analytical guidelines for the suitable connections between the precast members. Over the last several years, two types of connections have been proposed for the prefabricated concrete bridge elements in seismic regions. The first type is called “emulative cast-in-place” which targets a similar seismic performance as that from a cast-in-place construction (e.g. formation of plastic hinges in the piers). This type of connection offers the advantage for prefabrication of the bridge elements which accelerates the bridge construction time. However, extensive damage to the bridge can be expected during a design level earthquake. Therefore, when referred in context of ABC, the emulative cast-in-place solution is called “ABC High Damage” in this research. The second type of the proposed connections for ABC in seismic regions is a nonemulative solution called “Dissipative Controlled Rocking” (DCR). DCR connections combine unbonded post-tensioning tendons with external energy dissipaters between the precast members. The unbonded post-tensioning provides self centering for the bridge with dissipaters absorbing the seismic energy. DCR connections are traditionally called "Hybrid" connections". They were primarily developed for multi-storey precast buildings in the late 1990s. Past observations from seismic performance of the precast buildings incorporating DCR connections, have shown minimal damage and business disruption in the structure following a major earthquake. Therefore, when DCR connections are used in ABC context, it can be called “ABC Low Damage”. In this thesis, the use of emulative and DCR connections for ABC High Damage and ABC Low Damage has been thoroughly developed and experimentally tested. A series of quasi-static cyclic tests are performed on half-scale fully prefabricated cantilever and multi-column bridge piers. The specimens incorporate emulative and DCR connections between the precast elements. Several types of innovative dissipaters that can be used with DCR connections in ABC Low Damage, have been developed and experimentally validated. The design procedure, detailing consideration, construction technology, assembly sequence, experimental results, seismic performance, and analytical modeling, are presented for each type of ABC solutions discussed in the study. Qualitative and quantitative comparisons between the seismic performance of ABC High Damage and ABC Low Damage are also thoroughly presented. The research concludes that ABC Low Damage offers the best seismic performance compared to ABC High Damage and cast-in-place solutions. The life-cycle cost analysis and seismic loss assessment for the above solutions are outside the scope this study. However, past research works on similar topics have shown that if the life-cycle cost of a bridge is considered, then the traditional cast-in-place, ABC High Damage, and ABC Low Damage solutions may result in similar total cost.