The seismic performance of prefabricated reinforced concrete shear walls is a key point in the safety of the whole assembly structure under earthquake actions. In this study, six specimens of reinforced concrete shear walls were assembled with a cast-in-place vertical joint with a straight, L, or convex shape. The specimens were tested using a low cyclic loading test under an axial compression ratio of 0.2 or 0.3. The stress process, failure pattern, and hysteretic curve of each specimen were measured. Combined with a numerical analysis using the finite element method, the variations in the bearing capacity, stiffness degradation, ductility, and energy dissipation capacity of the tested specimens were analyzed. Results showed that all specimens failed in a shear pattern without an obvious failure phenomenon along the vertical joint. The hysteresis curves exhibited an obvious pinch phenomenon and good deformation ability. The seismic behavior decreased in sequence for the shear walls assembled with a cast-in-place vertical joint with a straight, L, or convex shape, while a higher axial compression ratio improved the bearing capacity of the shear walls. The shear wall with an L-shaped vertical joint had similar seismic behavior to that with a straight vertical joint, but the shear wall with a convex vertical joint exhibited a decrease of 8.5% and 10.9% in bearing capacity, 18.2% and 1.2% in ductility, and 13.1% and 20.6% in energy dissipation, respectively, under an axial compression ratio of 0.2 and 0.3. The bearing mechanisms of shear walls with different vertical joints are explained with the numerical analysis of the stress vector maps of concrete and the stress cloud maps of reinforcements at different stress levels.

In the monolithic precast concrete shear-wall structure, the bonding property of cast-in-situ joints to precast concrete walls is important to ensure the entire structural performance. Aiming to the vertical joint of precast concrete walls, an experimental study was carried out considering the factors including the strength of precast and joint concretes, as well as the interface processing and casting age of precast concrete. The micro-expansion self-compacting concrete was used for the cast-in-situ joints. The interfacial bonding strength between joint and precast concrete was measured by splitting tensile test. Results show that the interfacial bonding strength was benefited from the increasing strength of joint concrete and the spraying binder paste on the interface of precast concrete, and unbenefited from the overtime storage of precast concrete. The washed rough surface with exposed aggregates improved the interfacial bonding strength, which increased with the increasing roughness. Based on the test results, the limits of the strength grade of joint concrete and the roughness of washed rough surface are proposed to get the interfacial bonding strength equivalent to the tensile strength of precast concrete. Meanwhile, the spraying of binder paste on precast concrete is a good choice, the storage time of precast components is a better limit within 28 days.

When the vertical joints of monolithic precast concrete structures are cast by self-compacting concrete, the design of the formwork under rational lateral pressure of self-compacting concrete becomes a key technical issue. In this paper, a prototype simulation test was conducted for the pouring of self-compacting concrete in the vertical joint of precast concrete walls. The self-compacting concrete was continuously poured from the top of vertical joints with a height of 2.8 m without any assistance such as a delivery tube. The formwork pressure of self-compacting concrete was measured at different heights with varying casting time. Results showed that the lateral pressure increased with the increase in slump-flow of fresh self-compacting concrete, reaching a peak value of about 70 kPa at a height of about 600 mm from the bottom of formwork. Compared to the concrete with a slump-flow of 550 mm, the self-compacting concrete with the slump-flow reached 655 mm and 755 mm, presenting an increase in the peak lateral pressure by 31.5% and 44.9%, respectively. A method for calculating the lateral pressure of self-compacting concrete on the joint formwork is proposed using the analysis of enveloped test curves. Under the condition with enough strength and limited deformation of the joint formwork, the optimal design of aluminum alloy formwork is determined using finite element analysis. This provides a sci-tech foundation of the optimal design to lighten the weight of joint formwork to improve the installation efficiency and reduce the manual power cost.

Although studies have been performed on the recycled aggregate made of waste concrete for the production of new concrete, the new concrete with 100% recycled coarse aggregate and manufactured sand (abbreviated as RAMC) still needs to be researched for structural applications. In this paper, an experimental study was performed on seven groups, including fourteen reinforced RAMC beams under the simply supported four-point loading test, considering the factors of the strength of RAMC and the reinforcement ratio of longitudinal tensile rebars. Based on the test results, the cracking resistance, the bearing capacity, the crack width, the flexural stiffness and the mid-span deflection of reinforced RAMC beams in bending are discussed and examined by using the formulas of conventional reinforced concrete beams. Results show that an obvious effect of reinforcement ratio was present, while less so was that of the strength of RAMC. With the comparison of predicted values by the formulas of conventional reinforced concrete beams, the reinforced RAMC beams decreased cracking resistance by about 20%, increased crack width by about 15% and increased mid-span deflection by about 10%, although the same bearing capacity can be reached. The results directly relate to the lower tensile strength of RAMC which should be further improved.