• Steel and Composite Structures
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• v.29 no.5
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• pp.603-622
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• 2018

Precast concrete structures are erected from individual prefabricated components, which are assembled on-site using different types of connections. In the present design of these structures, beam-to-column connections are assumed pin jointed. Bolted billet beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is currently limited information concerning their detailed structural behaviour under vertical loadings. The experimental work has involved the determination of moment-relative rotation relationships for semi-rigid precast concrete connections in full-scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and bolt arrangements conformed to successful commercial practice. Proprietary hollow core floor slabs were tied to the beams by 2T25 tensile reinforcing bars, which also provide the in-plane continuity across the connections. The contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. The flexural strength of the connections in the double-sided tests was at least 0.93 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.94 to 1.94 times the flexural stiffness of the attached beam. In general, the double-sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided bolted billet connection test results are presented in this paper. The behaviour of single sided bolted billet connection test results is the subject of another paper.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.12-13
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• 2021

Methods for the manufacture, erection, and assembly of heavy frame modules were proposed. Interferences among precast members were prevented by using bolted metal plates for dry precast beam-to-column joints during assembly with a clearance for tolerance implementing grouted concrete filler plates instead of metal filler plates. Clearances for tolerances were provided to avoid conflictions among components during erection phases. These gaps were, then, grouted by high-strength mortar. The constructability of new connections of a beam-to-column joint using bolted metal plates for precast structures was examined using a full-scale assembly test in which practical observations indicated that members could be aligned and placed accurately in both horizontal and vertical directions, leading to a fast and convenient assembling. Bolt holes of the endplate were properly aligned using couplers with 30 mm fastened length embedded in the columns. The assembly test demonstrated the erection safety and structural stability of the proposed joints that were without filler plates when they were subjected to heavy loads at the time of their erection. The facile and rapid assembly of precast beam-to-column connections with a 30 mm tolerance was observed. The proposed assembly method is rapid, sustainable, and resilient, replacing the conventional methods of concrete frame construction, offering a connection that can be used in constructing infrastructure, such as buildings and pipe-rack frames.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.181-185
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• 2003

The composite structural system with reinforced concrete column and steel beam has some advantages in the structural efficiency by complementing the shortcomings between the two systems. The system, however, has also a lot of problems in earthquake-proof capacity and construction process because it is wet method of construction. So, this paper proposed PCS(Precast Concrete Column and Steel Beam) structural system with dry method of construction. Purpose of this study is to enhance merit and control failure mechanism by installing Dog-Bone on H-beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.425-428
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• 2004

Nonlinear finite element analysis is conducted to predict the structural behavior of precast concrete column and steel beam connected by using bolted connections. The Nonlinear FEM program is based on the modified compression field theory which has good accuracy in the concrete structures. The link element is properly used to model the discontinuity between precast concrete column and steel beam. Predictions from the proposed model are compared with experimental results and it is concluded that structural behaviors of the composite structures, such as strength capacity, crack pattern and failure mode, can be predicted quite successfully.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.14-15
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• 2013

Green Frame is precast concrete column-beam structure. There are three types on column connection. The coupler type which is one of the three, need to be improved because of unstability caused by pre-installation of column before casting the slab, and quality deterioration caused by lack of workspace. Therefore, in this study, new coupler connection type with thread rebar is suggested. The result of this study shall be used for the efficiency analysis of the new coupler connection.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.441-450
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• 2010

This is a preliminary study on the development of precast beam-column joints for dry construction methodology. Precast beam column joints with thru-connectors (BCJ_TC) using high strength bars or PS strands were developed and their seismic performance including strength degradation, stiffness degradation and energy dissipation capacity was experimentally evaluated. Test results showed that compressive failures at the end blocks of PC beam members occurred dominantly while PC columns including panel zones were free from any damage. However, the connections confined with CFRP at the end block showed much improved seismic performance than that of the unconfined connections. Connections with neoprene pad fillers between beam and column interfaces were better than the other connections in all the seismic performances except initial stiffness. To improve the seismic performances of BCJ_TC, compressive strength of the concrete at the end block need to be increased to compensate for the additional compressive stresses due to unbonded connectors and deformation of connectors should be controlled respectively.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.657-666
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• 2006

The precast concrete beam-column connectors to retrofit an apartment building were investigated experimentally. Five precast concrete beam-column connectors were considered to develop a modified model which was adapted to domestic construction conditions from the DDC(dywidag ductile connection) of Germany. Special H-shape steel hardware was used to decrease the width of column and beams for the construction of external frames in apartments. It was found that the DDC had high joint strength and ductility, however failed in inclined shear crackings in the columns. The modified one showed better behaviors in tests because they did not show critical column crackings at failure. The test result of modified one with grouting was compared to that of the one without grouting within the duct. The one with grouting showed higher strength and ductility in failure than that without grouting.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.497-506
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• 2006

The precast concrete beam-column connectors for the high-rise office buildings were investigated experimentally in this study. The specimens of general precast beam-column connector which is used in a domestic site, specimen of DDC(dywidag ductile connectors) of Germany, and specimen of DDC with post-tensioning and modified DDC with post-tensioning were constructed and tested to verify the safety. The DDC with and without post-tensioning showed reliable joint strength and ductility but failed in critical inclined shear crackings at the column. The modified one showed better behaviors in tests because they did not show critical column crackings at failure. The use of prestressing did not helpful significantly to increase the strength and ductility of connectors but helpful only to develop self-centering behavior for stability.

• Structural Engineering and Mechanics
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• v.82 no.1
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• pp.55-67
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• 2022

The precast reinforced concrete frame system is a method for industrialization of construction. However, the seismic performance factor of this structural system is not explicitly clarified in some existing building codes. In this paper, the seismic performance factor for the existing precast concrete building frame systems with cast-in-situ reinforced shear walls were evaluated. Nonlinear behavior of the precast beam-column joints and cast-in-situ reinforced shear walls were considered in the modeling of the structures. The ATC-19's coefficient method was used for calculating the seismic performance factor and the FEMA P-695's approach was adopted for evaluating the accuracy of the computed seismic performance factor. The results showed that the over-strength factor varies from 2 to 2.63 and the seismic performance factor (R factor) varies from 5.1 to 8.95 concerning the height of the structure. Also, it was proved that all of the examined buildings have adequate safety against the collapse at the MCE level of earthquake, so the validity of R factors was confirmed. The obtained incremental dynamic analysis (IDA) results indicated that the minimum adjusted collapse margin ratio (ACMR) of the precast buildings representing the seismic vulnerability of the structures approximately equaled to 2.7, and pass the requirements of FEMA P-695.

• Earthquakes and Structures
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• v.8 no.1
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• pp.1-18
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• 2015

A simple method of assessing the risk of overturning of precast reinforced concrete columns is presented in this paper. The displacement-based methodology introduced herein is distinguished from conventional force-based codified methods of aseismic design of structures. As evidenced by results from field tests precast reinforced concrete columns can be displaced to a generous limit without sustaining damage and then fully recover from most of the displacement afterwards. Realistic predictions of the displacement demand of such (rocking) system in conjunction with the displacement capacity estimates enable fragility curves for overturning to be constructed. The interesting observation from the developed fragility curves is that the probability of failure of the precast soft-storey column decreases with increasing size of the column importantly illustrating the "size effect" phenomenon.