Abstract In order to study the seismic performance of post-tensioned precast prestressed slab-beam-column composite joint under low cycle loads, ABAQUS was used to simulate the quasi-static behavior of the composite joint. On the premise of verifying the accuracy of the FEM for post-tensioned precast prestressed concrete joints, a comparative analysis was conducted on the hysteresis performance, bearing capacity, energy consumption performance, and deformation capacity differences between concrete joint and composite joints. The seismic performance of the post-tensioned prestressed composite joint has been obtained, providing assistance for the design of the joint.

Progressive collapse resistance is more critical for precast concrete than cast-in-place structures. Most existing studies utilized scaled-down and quasi-static pushdown tests on substructures with rigid constraints under key member failure scenarios. However, the connection details, the spatial action of floors and the constraint stiffness of the remaining structure significantly affect the structure's progressive collapse resistance. Full-scale structural testing is the most direct method to evaluate the progressive collapse resistance of a new prefabricated structure, although it is difficult and costly to load and measure. A 2 x 2 bay 5-story full-scale frame structure was constructed according to the minimum requirements of the Code for Seismic Design of Buildings to investigate the progressive collapse resistance of a new precast, prestressed, efficiently fabricated frame (PPEFF) system. The structure's dynamic performance was analyzed by removing the 4th-floor edge column and bottom corner column. The slider and double micro-friction surface configuration proved suitable for the rapid removal of large axial force columns in a full-scale progressive collapse experiment. The layout of the full-scale structural test and the structure's dynamic responses are described. The effect of the lateral constraint stiffness and the duration of column removal on the dynamic response of the test structure were analyzed using finite element analysis. The progressive collapse resistance mechanism of the PPEFF structure was discussed. The PPEFF system remained in an elastic state and exhibited good progressive collapse resistance.

Abstract To further improve the installation efficiency of commonly used reinforced concrete composite slabs with lattice girders in China, an Improved Large Span Propping System is proposed. This article investigates the mechanical properties of the new propping system through in-situ monitoring. The monitoring results show that the displacement and stress of the prefabricated layer can meet the requirements of current Chinese standards, which indicates the feasibility of the new support system. Compared with the original Large Span Propping System, the new propping system can further utilize the bending stiffness of the prefabricated layer and reduce the installation amount of the lower propping frame.

The precast prestressed efficiently fabricated frame (PPEFF) represents a rapid assembly system. However, it may possess limited energy-dissipating capacity when applied to high-rise buildings in high seismic-prone zones. To solve this problem, a precast prestressed efficiently fabricated frame with shear panel dampers (PPEFF-SPDs) is proposed in this paper. Along this vein, this study focuses on the effective modular techniques for damper installation as well as the seismic performance of a PPEFF-SPDs. To investigate the seismic performance of the PPEFF-SPDs, a 0.8-scale two-story specimen was tested using hybrid and quasi-static tests. The test results showed that the PPEFF-SPDs designed according to Chinese building codes exhibited reliable seismic performance with the corresponding performance objectives satisfied. The specimen displayed an effective and stable energy-dissipating capacity even when the inter-story drift ratios reached 2%, and the specimen damage conformed to the failure pattern foreseen for strong columns and weak beams. This study demonstrates the feasibility of the proposed PPEFF-SPDs and provides a promising alternative for the PPEFF in high seismic-prone zones.

A new kind of Precast Prestressed Efficiently Fabricated Frame (PPEFF) system known as the PPEFF system has been used in China for several years, however there are few reports in English. Based on the hybrid frame system, the PPEFF system adds a post-cast composite layer on the top of the precast beam-slab and eliminates the energy dissipation rebars at the lower part of the beam-column joint. This makes it easier to compose a two-way moment-resisting frame without reinforcement congestion in the joint and simplifies the construction of the slab-beam-column joint. This paper introduces the PPEFF system and establishes a nonlinear finite element model that can accurately simulate the seismic performance of the PPEFF joint under low cycle loading. The FEM can simulate the opening and closing of the contact surfaces among slabs, beams and columns, as well as plastic damage mechanism. Hysteresis curves of the PPEFF joint under every step of low cycle loading from the finite element analysis are compared with those from a previous PPEFF joint experiment, showing good agreement. The effects of slab, post-tensioned strands and energy dissipation rebars on the seismic performance of PPEFF joints are further analyzed in this paper. Based on the analysis, some suggestions for seismic design are given.

Prefabricated shear walls are currently widely applied in mid-to-high-rise structures. As a new type of structural form of assembled shear walls, the ring connection assembled concrete shear wall has clear mechanical mechanism, easy construction and better performance and other significant advantages, which are gradually being applied in actual engineering. However, few systematic studies are carried on this new type of shear wall structure, and a complete theoretical system for guiding the design could not be given, especially in terms of mechanical mechanism and seismic performance, more detailed research work is needed. This paper uses numerical simulation as the main method to study the influence of different design variables such as shear span ratio, buckle size, axial compression ratio on the mechanical properties of the connection area in shear wall and the overall seismic performance of the structure. In this way, the theoretical basis for further optimizing the structural performance of the shear wall connection with ring connection.

In order to investigate the behavior and characteristic of interface bearing capacity of concrete-filled square steel tube (abbr CFST), push-out tests on nine CFST short columns were carried out. Different stenderness ratio and interface treatment (with or without butter) were taken into account in the test. Based on the test results, the load-slip curves of each specimens were obtained. The magnitude and formation of the interface bearing capacity was analyzed. The developing process of the interface bearing capacity was studied by comparing the strain condition of steel tube with that of core concrete. In addition, the relationship between the mean bearing strength and slip at the interface was grasped through linear regression statistics analysis.