The experiment on precast frame system with the connection technique using tack-weld in beam to column rebars in beam-column joint under effects from gravity load | |
| Author | Myat Noe Pwint |
| Call Number | AIT Thesis no.ST-18-30 |
| Subject(s) | Precast concrete beams--Testing Structural frames--Joints |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-18-30 |
| Abstract | Precast concrete system becomes popular as it is attributable to the advantages associated with prefabrication, such as short construction time, better quality control, low sensitivity to weather conditions, reduced manpower requirement on site and the possibility of large spans through the use of pretension when compared with monolithically cast in place concrete structures. However, skill is required to design a joint that can be easily formed on site at the same time providing the necessary strength and ductility. Many types of precast connection have been developed, particularly beam to column connections in moment resisting frames, mostly using bolted, welded, prestressed and cast in place connection to be applicable for use in comparison with the monolithic reinforced concrete frames. Reliable connection behavior can only be verified by testing or proven performance. Therefore, performing tests on more precast beam to column connections for typical construction detail connections can be applicable for a large area of real construction projects with the necessary requirement for adequate design of precast reinforced concrete connections. Cast in place joint with tack-weld rebars in connection is one of the most typical precast beam-to-column connection detail in Thailand. So, one full scale precast interior beam to column connection using tack-weld rebars from the first floor of four stories commercial building was evaluated in comparison with the specimen with spliced-weld rebars in connection from previous research to check the performance of the behavior and performance. Testing was carried out under incremental uniformly distributed loading on both beams while no loading to column was applied. For research specimen, testing results showed that concrete cracking at connection from fracture in welding is the major cause of failure. Flexural cracks propagated rapidly and the crack width increased after failure of welding. Stiffness of joint increased rapidly with increase in loading until failure, after failure slope of moment curvature curve reduced significantly imposing higher stiffness degradation after failure. Flexural cracks occurred at a distance of less than two times depth of the beam, which is defined as the plastic hinge region according to ACI code. Joint with spliced-weld rebars in connection has higher load carrying capacity with satisfactory performance than the one with tack-weld rebar in connection of precast concrete structure. Poor performance in terms of load-displacement, load-curvature, shear deformation and crack patterns were found out in the tack-weld rebar in connection. More concentrated cracks occurred in connection using spliced-weld rebar while wider flexural cracks adjoining altogether were found out in connection with tack-weld rebar. Careful control of quality in construction and welding should be done for the precast beam-column connection to have high load carrying capacity with satisfactory performance to make reliable precast concrete connection in comparison with the monolithic cast in place construction system. |
| Year | 2018 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-18-30 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Punchet Thammarak; |
| Examination Committee(s) | Pennung Warnitchai;Anwar, Naveed; |
| Scholarship Donor(s) | AIT Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2018 |