Experimental Research on Seismic Performance of a New-Type of R/C Beam-Column Joints with End Plates

This paper presents a new-type of fabricated beam-column connections with end plates. The joint details are as follows: the concrete beams are connected to column by end plates and six high strength long bolts passing through the core area. In addition, in order to increase the stiffness and shear strength, stirrups are replaced by the steel plate hoop in the core zone. To examine the fail behavior of the fabricated beam-column connection specimens, a quasi-static test is conducted for nine full-scale models to obtain the hysteresis curves, skeleton curves, ductility, energy dissipation capacity, and other seismic indicators. The experimental results show that all specimens failed in bending in a malleable way with a beam plastic hinge and the hysteresis curves are excellently plump for the end plate connections. From the seismic indexes, the fabricated connection specimens exhibit better seismic performance, which can provide reference for the application of prefabricated frame structure in the earthquake area.

Comparative Study on Seismic Response of Reinforced Concrete Frames with SMA in Column and Beam Plastic Hinge Zones

This paper presents a comparative analytical study on seismic response of low rise three storeys concrete frame reinforced with super-elastic material as rebar elements. The super-elastic shape memory alloy rebars were used as reinforcement in two plastic hinge zones of the frame, beam plastic hinge zones and column plastic hinge zones. The response of the frame structure with two different reinforced cases is compared to response of the frame structure reinforced with regular steel material. Nonlinear dynamic time history analysis is performed in this study. Three different great earthquake ground motions were used to determine the seismic response of the frame structures in terms of frame top displacement time history and inter-storey drift along the frame height for different cases of reinforcements. Results obtained from the analysis show that the seismic response of low rise frame reinforced with super-elastic SMA rebars is affected by the zone of which SMA rebar are used in reinforcement. The SMA column reinforcement is more effective than SMA beam reinforcement in reducing the frame response.

CONTRIBUTION OF CONCRETE TO SHEAR STRENGTH OF RC BEAMS FAILING IN SHEAR

Reinforced concrete (RC) beams with light transverse reinforcement are vulnerable to shear failure during seismic response. In order to prevent brittle shear failures at beam plastic hinge regions of earthquake-resistant structures, the Turkish Earthquake Code and ACI318 require the use of sufficient transverse reinforcement to resist the total expected shear demand. These codes tend to be excessively conservative and, in some cases, the contribution of the concrete to the shear strength is neglected. The aim of this study is to investigate the contribution of concrete to shear strength of RC beams failing in shear experimentally. The beams were tested under monotonically increasing reversed cyclic loading to determine the concrete contribution to shear strength. It is observed that the concrete contribution to the shear strength at ultimate state ranges from 18% to 69% of the ultimate strength.

Crack Pattern and Ductility of Connections Composed of CSSEUHSC Columns and SEC Beams under Cycle Loads

In order to investigate the crack pattern and ductility of connection composed of cross shaped steel encased ultra high strength concrete (CSSEUHSC) columns and steel encased concrete (SEC) beams under cycle loads, six interior connection specimens were tested in the laboratory. It was found that cracks appeared in the connection core regions and at the beam end for all specimens, and all the connections behaved in a ductile manner and failed in bending with a beam plastic hinge and shearing in the connection core region. The experimental results indicated that test parameters of connection composed of CSSEUHSC columns and SEC beams with good crack resistance performance may be referred for engineering application.

Crack Pattern and Ductility of Steel Reinforced Ultra High Strength Concrete Composite Joint Subjected to Reversal Cycle Load

In order to investigate the seismic damage and performance of steel reinforced ultra high strength concrete composite joint subjected to reversal cycle load, six interior strong-column-weak-beam joint specimens were tested with various axial load ratio and volumetric stirrup ratio. A discussion on the crack mode and ductility was presented. It was found that all joint specimens failed in bending with a beam plastic hinge in a ductile manner, with crack propagation different from the weak-column-strong-beam joint. The experimental results indicated that test parameters of the steel reinforced ultra high strength concrete composite joint with good seismic performance may be referred for engineering application.

Reinforced Concrete Wide-Beam Construction vs. Conventional Construction: Resistance to Lateral Earthquake Loads

Experiments and analyses were conducted to address concerns about performance of reinforced concrete connections with shallow, wide beams subjected to lateral earthquake loading and to compare behavior of wide beam connections to that of conventional connections. Two wide beam-column-slab connections and one conventional beam-column-slab connection were subjected to cycles of reversing lateral displacements up to 5% drift. The conventional beam and wide beam connections exhibited similar overall load-displacement behavior, with similar beam plastic hinge development. The wide beam connections dissipated almost as much energy as the conventional beam connection and had greater slab participation and less joint and beam shear cracking than the conventional beam connection. Experimentally determined wide beam connection stiffness was closer to the conventional beam connection stiffness than had been predicted. Refined models were developed, with features such as rigid end offsets for wide beam connections, to better represent observed behavior. Nonlinear models were also developed that accurately captured differences in energy dissipation as well as stiffness.

Influence of loading history on the response of a reinforced concrete beam

An investigation considering the influence of loading histories on the performance of a reinforced concrete beam plastic hinge is described. Twelve loading histories were considered, including conventional procedures employed in the United States, Japan and New Zealand, and artificially generated histories derived from recorded earthquake ground motions. Details of the prototype structure and the test beam are described, followed by comprehensive reporting o f experimental data. Performance descriptors and further treatment of the experimental data are presented in a companion paper.