• Steel and Composite Structures
• /
• v.19 no.1
• /
• pp.209-221
• /
• 2015

Results from an experimental study on the seismic response of six composite reinforced concrete column-to-steel beam interior joints are presented. The primary variable investigated is the details in the joint. For the basic specimen, the main subassemblies of the beam and column are both continuous, and the steel beam flanges extended to the joint are partly cut off. Transverse beam, steel band plates, cove plates, X shape reinforcement bars and end plates are used in the other five specimens, respectively. After the joint steel panel yielded, two failure modes were observed during the test: local failure in Specimens 1, 2 and 4, shear failure in Specimens 3, 5 and 6. Specimens 6, 3, 5 and 4 have a better strength and deformation capacity than the other two specimens for the effectiveness of their subassemblies. For Specimens 2 and 4, though the performance of strength degradation and stiffness degradation are not as good as the other four specimens, they all have excellent energy dissipation capacity comparing to the RC joint, or the Steel Reinforced Concrete (SRC) joint. Based on the test result, some suggestions are presented for the design of composite RCS joint.

• Earthquakes and Structures
• /
• v.19 no.5
• /
• pp.315-329
• /
• 2020

Through bolt connections in Concrete Filled Steel Tubes (CFSTs) has been proved to be good in terms of seismic performance and constructability. Stiffened extended end plate connection with full through type bolt helps to avoid field weld altogether, and hence to improve the quality of joints. An experimental study was conducted on the hysteretic performance of square interior beam-column connections using flat extended end plates with through bolt. The study focuses on the effect of the bond between the tie rod and the core concrete on the cyclic performance of the joint. The study also quantifies how much the interior joint is getting strengthened due to the confinement effect induced by bi-directional bolting, which is widely used in 3D moment resisting frames. For a better understanding of the mechanism and for the prediction of shear capacity of the panel zone, a mathematical model was generated. The various parameters included in the model are the influence of axial load, amount of prestress induced by bolt tightening, anchorage, and the concrete strut action. The study investigates the strength, stiffness, ductility, and energy dissipation characteristics. The results indicate that the seismic resistance is at par with American Institute of Steel Construction (AISC) seismic recommendations. The bidirectional bolting and bond effect have got remarkable influence on the performance of joints.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.09a
• /
• pp.319-325
• /
• 2003

The fragility curves of seismic retrofitted bridges by steel jacketing of bridge columns and restrainers at expansion joints after the 1994 Northridge earthquake are developed. Fragility curves are represented by lognormal distribution functions with two parameters(fragility parameters consisting of median and log-standard deviation) and developed as a function of peak ground acceleration (PGA). Two parameters in the lognormal distribution are estimated by the maximum likelihood method. The sixty ground acceleration time histories for Los Angeles area developed for FEMA SAC project are used for the dynamic analysis of the bridges and a computer code is developed to calculate hysterestic parameters of bridge columns before and after steel jacketing. The effect of retrofit is expressed in terms of the increase of the median value of the fragility curve for the retrofitted bridge from that of the bridge before retrofit. The comparison of fragility curves of the bridges before and after column retrofit demonstrates that the improvement of the bridges with steel jacketing on the seismic performance is excellent for the damage states defined in this study. The comparison of fragility curves of the bridges before and after restrainers at expansion joints also shows the improvement in the seismic performance of restrained bridges for the severe damage states.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.09a
• /
• pp.133-140
• /
• 2003

The objective of this study is to clarify the seismic capacity and the characteristics in the hysteretic behavior of RC structures with non-seismic detailing. Interior and exterior beam-column subassemblages were selected from a ten-story RC building and six 1/3-scale specimens were constructed with three variables; (1) with and without slab, (2) with and without hoop bars in the Joint region, (3) upward and downward direction of anchorage for the bottom bar in beams of exterior beam-column subassemblage. The test results have shown; (1) in case of interior beam-column subassemblage, there is no almost difference between nonseismic and seismic details in the strength and ductility capacity; (2) the Korean practice of anchorage (downward and 25 $d_{b}$ anchorage length) in the exterior Joint caused the 10％~20％ reduction of strength and 27％ reduction of ductility iii comparison with tile case of seismic details; and the existence of hoop bars in the joint region shows no effect in shear strain.n.

• Nuclear Engineering and Technology
• /
• v.46 no.5
• /
• pp.595-604
• /
• 2014

SILER (Seismic-Initiated event risk mitigation in LEad-cooled Reactors) is a Collaborative Project, partially funded by the European Commission in the $7^{th}$ Framework Programme, aimed at studying the risk associated to seismic-initiated events in Generation IV Heavy Liquid Metal reactors, and developing adequate protection measures. The project started in October 2011, and will run for a duration of three years. The attention of SILER is focused on the evaluation of the effects of earthquakes, with particular regards to beyond-design seismic events, and to the identification of mitigation strategies, acting both on structures and components design. Special efforts are devoted to the development of seismic isolation devices and related interface components. Two reference designs, at the state of development available at the beginning of the project and coming from the $6^{th}$ Framework Programme, have been considered: ELSY (European Lead Fast Reactor) for the Lead Fast Reactors (LFR), and MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) for the Accelerator-Driven Systems (ADS). This paper describes the main activities and results obtained so far, paying particular attention to the development of seismic isolators, and the interface components which must be installed between the isolated reactor building and the non-isolated parts of the plant, such as the pipe expansion joints and the joint-cover of the seismic gap.

• Earthquakes and Structures
• /
• v.22 no.4
• /
• pp.387-399
• /
• 2022

To study the seismic damage of masonry structures and understand the characteristics of the multi-intensity region, according to the Dujiang weir urbanization of China Wenchuan earthquake, the deterioration of 3991 masonry structures was summarized and statistically analysed. First, the seismic damage of multistory masonry structures in this area was investigated. The primary seismic damage of components was as follows: Damage of walls, openings, joints of longitudinal and transverse walls, windows (lower) walls, and tie columns. Many masonry structures with seismic designs were basically intact. Second, according to the main factors of construction, seismic intensity code levels survey, and influence on the seismic capacity, a vulnerability matrix calculation model was proposed to establish a vulnerability prediction matrix, and a comparative analysis was made based on the empirical seismic damage investigation matrix. The vulnerability prediction matrix was established using the proposed vulnerability matrix calculation model. The fitting relationship between the vulnerability prediction matrix and the actual seismic damage investigation matrix was compared and analysed. The relationship curves of the mean damage index for macrointensity and ground motion parameters were drawn through calculation and analysis, respectively. The numerical analysis was performed based on actual ground motion observation records, and fitting models of PGA, PGV, and MSDI were proposed.

• Earthquakes and Structures
• /
• v.10 no.2
• /
• pp.313-328
• /
• 2016

Beam-column joints are recognized as one of the most critical and vulnerable zones of a Reinforced Concrete (RC) moment resisting structure subjected to seismic loads. The performance of the deficient beam-column joints can be improved by retrofitting these joints by jacketing them with varied materials like concrete, steel, FRP and ferrocement. In the present study strength behavior of RCC exterior beam-column joints, initially loaded to a prefixed percentage of the ultimate load, and retrofitted using ferrocement jacketing using two different wrapping schemes has been studied and presented. In retrofitting scheme, RS-I, wire mesh is provided in L shape at top and at bottom of the beam-column joint, whereas, in scheme RS-II along with wire mesh in L shape at top and bottom wire mesh is also provided diagonally to the joint. The results of these retrofitted beam-column joints have been compared with those of the controlled joint specimens. The results show an improvement in the ultimate load carrying capacity and yield load of the retrofitted specimens. However, no improvement in the ductility and energy absorption has been observed.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.9
• /
• pp.41-55
• /
• 2014

In performing seismic analysis of tunnels, it is a common practice to ignore the rock joints and to assume that the rock mass surrounding the tunnel is continuous. The applicability of this assumption has not yet been validated in detail. This study performs a series of pseudo-static discrete element analyses to evaluate the effect of rock joint on the seismic response of tunnels. The parameters considered are joint intersection location, joint spacing, joint stiffness, joint dip, and interface stiffness. The results show that the joint stiffness has the most critical influence on the tunnel response. The tunnel response increases with the spacing, resulting in localized concentration of moment and shear stress. The response of the tunnel is the lowest for joints dipping at $45^{\circ}$. This is because large shear stresses result in rotation of the principal planes by $45^{\circ}$. In summary, the weathered and smooth, vertical or horizontal, and widely spaced joint set will significantly increase the tunnel response under seismic loading. The tunnel linings are shown to be most susceptible to damage due to induced shear stress, and therefore should be checked in the seismic design.

• Journal of the Korea Concrete Institute
• /
• v.28 no.2
• /
• pp.235-244
• /
• 2016

This study was conducted to verify seismic performance of special moment frame's joints at roof-level with high-strength concrete and SD600 bars. K-RC-H was designed according to the seismic code and K-HPFRC-H had 150% of the original hoop spacing and 1.0% steel fiber volume fraction compared with K-RC-H. Both specimens had remarkable seismic performance without noticeable decrease in moment, but with very good energy dissipation before rebar failure. The U-bars in the joint sufficiently constrained rebar's action that pushed the cover upward. SD600 bars with $1.25l_{dt}$ had minimum slip in the joint. It was considered that the steel fiber contributed to improvement of the bending moment and joint shear distortion, and the result showed that it would be possible to increase the hoop spacing to 150% of the regular spacing.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.6
• /
• pp.63-68
• /
• 2007

The purpose of this study was to develop a new connection method between steel beams and PC columns known as SL connectors. Composite moment frames consisting of PC columns (or composite columns) and steel beams make the best use of advantages of both concrete and steel materials. However, the connection between two members of different materials can be complex and/or increase the fabrication costs significantly. The concept of SL connectors is based on using wedges and the emphasis is on a self-locking (SL) feature. SL connectors are easy to install and provide better seismic performance compared to conventional connections. To evaluate the seismic performance of the steel beam-to-PC column joints with SL connectors, cyclic load tests were conducted. Test result showed that steel beam-to-concrete column joint with SL connectors was able to provide sufficient performance for use in seismic resistant moment frames.