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Precast concrete systems are mainly used to construct residential buildings in Japan. The systems include precast concrete wall structures for low-to-medium-rise buildings and frame structures for medium to high-rise buildings. Most of the precast members are produced in fabricating plants and shipped to the site. Beam-column joints in precast systems are designed using essentially the same design philosophy but considerably different details, as used in cast-in-place construction. The details of the joints are usually examined from the structural viewpoint by experimental tests and from the construction viewpoint by mock-up tests. This paper is intended to give an overview of beam-column joints used in precast concrete moment-resisting frame structures. Aseismic design and details of the joints are described and a few examples of construction practice are illustrated. Emphasis is placed on joints in high-rise construction using precast concrete systems.

Reversed cyclic loading tests were carried out for 18 reinforced concrete exterior beam-column subassemblages designed in accordance with the principle that yielding of adjoining beam or column precedes joint shear failure. Column axial force, amount of joint hoop reinforcement, existence of intermediate column bars, and moment-resisting capacity ratio of beam to column were selected as experimental variables. Test results showed that the ductility of the subassemblages increased by column axial compressive force and the amount of the joint hoop reinforcements. The existence of the intermediate column bars was also effective in increasing the ductility. On the basis of thorough consideration of the test results, a critical cumulative displacement ductility factor was quantified as a function of the test variables, and was ascertained to be a very effective value to evaluate the aseismic performance of exterior beam-column subassemblages.

Two series of experiments on the performance of beam-column joints in reinforced concrete frames were carried out. In Series I, the influence of the transverse reinforcement in the joint and/or the portion of the beam end connected to the column was investigated. From the test results, it is derived that heavy transverse joint reinforcement may reduce the slippage of beam bars in the joint and enhance the joint stiffness after cracking, and the similar transverse shear type reinforcement in the beam end has little effect on relieving the stiffness after degradation of a frame due to the deterioration of bond along the beam bars within the joint. In Series II, the effects of locating a plastic hinge in the beam away from the column face were examined. The test results show that the bond deterioration of beam bars within the joint may be prevented effectively by plastic hinge relocation, but shear-sliding deformation may occur at the plastic hinge away from the column face owing to the inevitable increased shear force in the beam. A new arrangement of beam bars to improve the behavior of the plastic hinge is proposed.

In structures subjected to lateral loading, slab reinforcement acting as effective tensile reinforcement of the beams has been found to increase significantly the beam flexural strength. The enhanced beam flexural strength has several effects on the structural behavior, including a shift in the ratio of strengths between the beams and other members. This may result in a failure mechanism different from that anticipated. The slab contribution depends on several variables, including the connection type (interior or exterior), lateral deformation level, and lateral load history (uniaxial or multiaxial). This paper summarizes general behavior observed during isolated and multiple beam-column-slab connection tests. An approximation is given for estimating the amount of slab reinforcement to be considered as effective tensile reinforcement of the beams.

Proposes mechanisms of the transfer of forces to beam-column joints, generated under typical seismic actions in cast-in-place reinforced concrete slabs. One of the main objectives of the paper is to review behavioral models that should assist designers in visualizing the flow of internal forces in beam-column-slab subassemblages. It is postulated that membrane forces play a dominant role and that contributions of other actions, such as bending in slabs and torsion in transverse beams, are relatively unimportant, particularly when significant ductility demands arise during seismic motions. Locations at which slab reinforcements transmit tensile forces by means of bond to the surrounding concrete are considered to be particularly important in the assessment of the enhancement of beam flexural strength. The description of these phenomena is related to observations made during the testing of isolated reinforced concrete beam-column subassemblages with slabs simulating one-and two-way cast-in-place floor systems. Subsequently, the findings are extended to describe the perceived behavior of continuous floor slabs supported by beams of multibay ductile frames. The relevance of the flexural strength enhancement of beams to the design of beam-column joints and columns is briefly examined. Design recommendations are made, particularly with respect to the effective width of the tension flanges.