Precast Concrete Frame Structures Research Articles

Experimental study and seismic assessment on base isolated precast concrete frame structure with box connectors

The precast construction method offers fast and environmentally friendly solutions for sustainable development in construction. Various connection methods, including wet and dry, have been proposed to enhance assembly convenience. However, challenges remain in achieving complete assembly and considering disassembly processes, hindering post-earthquake restoration. This study introduces a precast RC structure system with easily assembled joints that facilitate disassembly. To enhance the structural system's adaptability to regions with high seismic intensity, rubber-bearing base isolation technology is employed to optimize its seismic performance. Shaking table tests were conducted to evaluate the structure system's dynamic response and seismic performance. Test results indicate that the isolation layer significantly decreases the acceleration response, inter-story drift ratios, floor shear forces, and strain of reinforcements. The isolation structure has a high probability of entering operational and immediate occupancy states during rare earthquakes. The deformation of the isolation bearings has a decisive impact on the overall seismic fragility of the isolation structure system.

Simplified test method for evaluating progressive collapse resistance of precast concrete frame structures

To evaluate the progressive collapse resistance of precast concrete (PC) structures, various test methods have been used in existing experimental studies. However, verification of whether the progressive collapse resistance can be evaluated equivalently by different test methods has been limitedly investigated. In this study, three simplified and three half-frame test specimens were tested under monotonic vertical loading to investigate the effects of the test method on their progressive collapse resistance. As the test parameters, types of test specimens (i.e., sub-frame, simplified, and half-frame specimens), and joint details (i.e., reinforced concrete (RC) continuous joint, PC with continuous joint, and PC with pinned joint) were directly compared. The test results showed that the progressive collapse resistance was primarily affected by the overall lateral stiffness of the exterior columns (Kh) rather than the test setup. When Kh increased in the simplified specimens, the axial force transferred by the beams increased, resulting in an increase in the peak strength (PCAA). Further, the effect of Kh on the peak strength was greater in PC specimens with pinned joints than in RC and PC specimens with continuous joints. To investigate the effect of Kh on the PCAA, a parametric study was conducted using the existing CAA strength model. The parametric study results also indicated that the relationship between the increase in Kh and PCAA was not significantly governed by the test setup for the same joint details. These results indicated that various simplified test methods can be used to evaluate the progressive collapse resistance of PC structures when an adequate range of Kh is provided. Based on the test and parametric study results, recommendations for progressive collapse tests were discussed.

Progressive collapse resistance of precast concrete beam–column assemblies using dry connections under uniformly distributed loading condition

Improving the integrity of precast concrete (PC) frame structures using dry connections is essential for enhancing their robustness against progressive collapse. Therefore, three PC beam–column assemblies using different dry connections specially designed to ensure the connectivity were experimentally examined under progressive collapse scenarios. And a seven-point loading tree device was adopted to simulate the uniformly distributed loading conditions in practical engineering. The connection details were classified as follows: normal top-and-seat angle connection in TSA, strengthened top-and-seat angle connection in STSA, and strengthened top-and-seat angle with high ductility longitudinal reinforcements in the plastic regions in DSTSA. Under small deformations, STSA had the highest first peak load attributable to its strengthened joint connection. TSA obtained a lower load than that of STSA because of the low joint connection stiffness. Meanwhile, DSTSA achieved the lowest load among the three specimens because the smoother surface of the high-ductility reinforcements (compared with that of normal ones) weakened its bond to the concrete. However, under large deformations, the high ductility of the reinforcements ensured the specimen integrity; consequently, the largest final load was achieved in DSTSA. On the contrary, the high joint stiffness and normal reinforcements in STSA hindered the beam end rotation, and the steel angle failed early in TSA. As a result, the two connections failed to ensure the specimen integrity. To further shed light on the resistance mechanisms of beam–column assemblies under the uniformly distributed loading condition, an iteration-based model was developed to calculate the first peak load under the beam and compressive arch actions. The maximum prediction error achieved was 12%. Based on the model, the load contribution from the friction effect of the loading device was identified as 27%. And it was found that during the collapse, increasing reinforcement deformation region that might be induced by slippage between the concrete and reinforcements could lead to a continuous increase in the horizontal reaction force after the specimen reaching the first peak load.

Dynamic progressive collapse response of 3D monolithic precast concrete frame structures considering slab effects

The robustness of precast concrete frame structures to withstand extreme events like explosions, impacts, fires and terrorist attacks has attracted growing attention. With the understanding of the static progressive collapse performances of 2D precast frame structures, research on the dynamic responses of 3D precast frame structures is pressing and high in demand. To evaluate the influence of floor slabs on dynamic progressive collapse responses of 3D precast concrete frame structures, an experimental program consisting of a beam-column (PC) and a beam-slab-column (PCS) specimens was first designed, followed by the analysis of the working mechanisms to resist progressive collapse. The modeling techniques for 2D PC and PCS substructures were then proposed and validated using the test results. The numerical strategy was further extended to simulate the dynamic progressive collapse responses of 3D PC- and PCS-frame structures. Results show that, under various column loss scenarios, floor slabs significantly improve progressive collapse resistances of 3D frame structures. Moreover, it reveals that the floor slabs have a remarkable effect on reducing the nodal displacements and the dynamic amplification factors.

Effect of infill walls on progressive collapse behavior of self-centering precast concrete frame

To study the effect of infill walls on the progressive collapse resisting-performance of self-centering precast concrete (PC) frame structures, three 1/2 scaled, two-span and two-story self-centering PC frame specimens with and without infill walls were tested under quasi-static pushdown loading regime. The test results showed that the failure modes of self-centering PC frames were governed by concrete cracking and local spalling at the beam ends under progressive collapse scenario. Compared with self-centering bare frame, the presence of infill walls provided additional load path, thereby reducing the concrete damage at the beam ends to some extent. The full infill walls with lower strength could still increase the initial stiffness and peak resistance of self-centering bare frame to 2.47 times and 1.33 times, while the infill walls with 20% opening ratio could increase to 2.21 times and 1.19 times, respectively. Nevertheless, the infill walls also reduced the self-centering capacity of the structures. Numerical analyses further indicated that the magnitude of prestress force of steel strands between beams and columns, the strength of bed joints as well as the width of infill walls had a great effect on the progressive collapse of self-centering infilled frames. Finally, based on numerical results, a reduction factor formula was proposed to quickly estimate the structural resistance of self-centering infilled frames with different opening ratios.

Seismic fragility analysis of precast concrete framed structures with dry connections

Seismic fragility analysis of precast concrete framed structures with dry connections

Estimation and analysis of the cumulative energy damage model for precast concrete nonrectangular column frame structures

A detailed characterization of structural damage progress is essential to performance-based seismic design for precast concrete nonrectangular column (PCNC) frame structures. The paper presents an experimental investigation into the damage behavior of the PCNC frame structures under reverse cyclic loading, including specimens PCFS1 and PCFS2 in bay and specimen PCFS3 in depth of a new precast residential building. Based on the experimental results, the damage mechanism of the PCNC frame structures was further discussed with the cumulative energy damage model proposed in this paper, and the influence of key structural parameters on the damage of the PCNC frame structures was examined, including energy dissipation adjusted factor, the residual deformation rate and the stiffness degradation rate. Available results indicated that the experimental damage curves of test specimens increased with the loading progress and acted with nonlinear damage characteristics, and PCNC frame structural damage behavior was sensitive to the axial compression ratio. For the proposed damage model, the calculation results were in good agreement with the experimental results. On the basis, the damage degree of the PCNC frame structures was divided into five performance levels including normal use, temporary use, use after repair, life safety and prevent collapse in the defined damage range of (0, 1). Elastic layer drift ratio limit was suggested to relax for PCNC frame structures. Final test results could provide a basis for the aseismic design and damage assessment of such structures after earthquake.

Experimental study on the structural behavior of exterior precast concrete beam-column joints with high-strength steel bars in field-cast RPC

To enhance the seismic performance of conventional precast concrete frame structures, this study introduces a novel precast high-performance concrete frame beam-column joint. We designed and conducted experiments on two full-scale precast concrete frame beam-column exterior joints, varying the presence of L-shaped steel reinforcement at the bottom of the beam-column joint. The findings reveal that the load-bearing capacity, hysteresis characteristics, stiffness degradation, and energy dissipation capacity of both joints significantly improve when using reactive powder concrete (RPC) poured into the joint connection area and L-shaped steel at the beam-column junction. A finite element model for these joints was further developed and validated based on the experimental data. Additionally, a parametric study was conducted to assess the impact of axial compression ratio and spacing of hoop bars in the joint area on joint behavior. Using an experimental fitting approach, a tri-linear skeleton curve model for the joints was established, offering a more precise representation of stress and deformation characteristics at each stage. The hysteretic curve generated from this restoring force model closely matches the experimental data, demonstrating the model’s ability to accurately depict the hysteretic behavior of beam-column joints in precast RPC/RC composite frames.

Performance of high strength steel bar splice with novel grouted deformed sleeve under tensile load

High-strength steel (HSS) bars can solve bar congestion problem in beam-column joints of monolithic precast concrete frame structure. Unfortunately, its application in precast concrete structures is greatly hindered by few researches on HSS bar grout splice. In this paper, utilizing large-diameter HRB600 reinforcements with specified yield strength of 600 MPa, 34 splice specimens were prepared considering the parameters of embedded length, grout strength and inner cavity structure of sleeve. Through uniaxial tension test, it is shown that the embedment length has the greatest effect on the structural performance of grouted splice. For the d28 bar grout splice, 8db is the minimum embedded length to ensure bar fracture failure, which is longer than the normal-strength steel bar grout splice. For the splices with embedded length not smaller than 5db and concentric ribs not less than five, excessive ribs set on the sleeve cannot significantly increase the tensile strength of the grouted splice, but further adding one rib still can effectively reduce the elastic residual deformation. Similar test results have been observed for the effect of grout strength. As the compressive strength increases from 95.3 MPa to 118.2 MPa, the tensile strength improves only by about 2.52%, but the residual deformation decreases significantly by 11.68% on average. For a high-strength large-diameter bar grout splice, it is recommended to set six concentric ribs at each side of the sleeve, and select 8db as the minimum embedded length to achieve reliable performance.

Research on Cost Control of Prefabricated Concrete Building Design Stage

The industrialization of new building represented by prefabricated building is advancing rapidly. The design stage is the key stage of cost control of the whole prefabricated project. Through the analysis of the main design tasks in the design process of prefabricated concrete building design stage on the cost of prefabricated concrete frame structure, the factors affecting the cost control difficulties are analyzed, and the corresponding control measures in the design stage are put forward to promote the development of prefabricated concrete building. Through the comparison of cost control design and application cost of engineering cases in the design stage, it is shown that the construction cost of precast concrete frame structure system can be saved through reasonable design scheme.

Development of a double-stage-yield dissipative beam-to-column joint: Experimental study and application for structural response control

Energy-dissipative beam-to-column joints are an effective method for improving the seismic performance of precast concrete (PC) frame structures. The development of double-stage-yield dampers is a new trend for realizing the comprehensive response control of structures under different levels of earthquakes. However, dissipative beam-to-column joints with double-stage-yield behaviors have rarely been investigated. In this study, a novel double-stage-yield dry-connected beam-to-column joint (DDBJ) is developed by combining a rotational friction damper and buckling-restrained slitted steel plates. First, experimental investigations were conducted, and the working mechanism and theoretical equations of the DDBJ were verified. Subsequently, a numerical simulation method for DDBJ was proposed based on OpenSees, which was proven to be capable of efficiently capturing the double-stage-yield behavior of DDBJ and was suitable for the response assessment of PC frames with DDBJ. Based on this method, the control effect of the DDBJ on the seismic responses of the PC frame was conclusively identified through a numerical comparison between a six-story reinforced concrete frame, a PC frame using single-stage-yield dissipative beam-to-column joints, and a PC frame using DDBJs, emphasizing the effects under four levels of earthquakes. The research outcomes of this study could provide new strategies for the seismic response control of PC frame structures.

A practical multiscale modeling strategy to model wet-type beam–column connections for seismic analysis of precast RC frame structures

Numerical models of beam–column connections are widely used in the seismic analysis of wet-type precast concrete frame structures. However, because of the trade-off between computational accuracy and efficiency, it is difficult to appropriately consider wet-type precast features by using existing numerical approaches. Therefore, this paper presents a multiscale modeling strategy based on OpenSees software, in which frame and solid elements are adopted to model the flexural behavior of precast members (beams/columns) and cast-in-place joint panels, respectively. Moreover, a multiscale interface is developed and implemented in OpenSees to establish the displacement compatibility and force equilibrium conditions of the interface between the frame and solid elements. The proposed strategy can capture the features of wet-type precast beam–column connections, including grouted splice sleeves, bond–slip, pre- and postcast concrete interfaces and shear deformations in the joint panel. The strategy is validated by experimental results on both the member and structural levels. Finally, an inelastic seismic analysis case study is developed to assess the computational efficiency of the proposed strategy.

Hybrid Test of Precast Concrete Frame with Energy-Dissipation Cladding Panel System

To investigate the influence of an energy-dissipation cladding panel system (EDCPS) on the dynamic responses of a precast concrete (PC) frame structure, a six-story, three-span planar frame structure with an EDCPS (called “damping structure”) and a counterpart planar bare frame structure (called “bare frame structure”) were designed. The middle span and bottom two stories of the frame were selected as the test substructures, whereas the rest were considered using the numerical substructure. Hybrid tests were conducted on the two structures under four earthquake levels. The test results indicated that the damage evolution characteristics of the PC frame were not affected by the introduction of EDCPS. The dampers in the EDCPS successfully yielded and dissipated seismic energy under the four earthquake levels. Moreover, the maximum inter-story drift ratio of the damping structure was reduced by 12.59%, 17.68%, and 10.34% under the design-basis earthquake, maximum considered earthquake, and very rare earthquake, respectively, exhibiting a satisfactory damage-control effect. The cladding panels remained intact under the four earthquake levels, indicating that this structure effectively prevents damage to the cladding panels. Finally, a numerical simulation method is recommended according to the damage characteristics of the damping structure and is validated against the test data.

Experimental study on the collapse-resistant performance of unbonded prestressed PC beam-column sub-assemblages with pinned connections

In precast concrete frame structures, it is imperative that beam-to-column connection has appropriate robustness and reliable axial resistance to defense against progressive collapse. Hence, a method of using pinned connection and unbonded posttensioning strands (UPSs) to mutually improve the collapse-resistant performance of precast concrete structures was proposed in this study. The pinned connections are used for connecting precast beams with columns at precast beam ends, and UPSs with straight profile are placed at the bottom of beam cross-section. In order to investigate whether the proposed method can enhance collapse-resistant capacity of precast concrete structures, static progressive collapse tests were conducted for the newly proposed precast concrete frame substructures with UPSs (UPPC frame substructures) and without UPSs (PC frame substructure). Moreover, influences of effective prestress level upon the collapse-resistant capacity of UPPC substructure were also investigated. Test results demonstrated that, similar to conventional RC frame structure, the compressive arch action (CAA) and catenary action (CTA) could also develop in the proposed UPPC substructures to avert progressive collapse. The UPPC substructure was able to develop 32% higher CAA capacity and 162% larger CTA capacity as compared to the PC substructure, indicating that the UPSs play a positive role in enhancing both its CAA and CTA. The CTA capacity of the PC substructure was 53.8% higher than that of CAA, which signifies that the pinned connection can be employed to improve structural robustness to mitigate progressive collapse. In addition, the increase of effective prestress level of UPSs is beneficial to the enhancement of CAA capacity of the UPPC substructure. However, higher effective prestress level is limited to improve its CTA capacity due to lower deformation capacity of UPSs. Subsequently, three-dimensional finite element models (FEMs) of the UPPC and PC substructures were developed by using ABAQUS software. By comparing experimental data with FEM results, it was concluded that the FEM could accurately predict the load–displacement curves, crack patterns and reinforcing ruptures of all the test specimens.

Research on design and numerical simulation of self-centering prefabricated RC beam-column joint with pre-pressed disc spring devices

To improve the resilience performance of precast concrete frame structure, a novel self-centering prefabricated concrete beam-column joint with controllable plastic hinge (PJ-CPH) is proposed in this manuscript. Controllable plastic hinge is an innovative connection configuration composed by pin shaft, rotational friction damper and disc spring self-centering devices. The rotational friction damper is used for withstanding bending moment and dissipating seismic energy. The disc spring self-centering device is used for withstanding bending moment and providing restoring force, while the pin shaft is merely used for withstanding shear force. A detailed design procedure was presented by introducing self-centering ratio α and moment amplification factor β. A flag-shaped hysteretic model of PJ-CPH was proposed, simultaneously, a numerical model was developed based on the OpenSees computational platforms. The numerical simulation analysis was carried out for four PJ-CPH models with different parameters and one cast-in-situ beam-column joint model under low cyclic loading. Analysis results indicate that the hysteretic curve obtained by theoretical calculation are in good agreement with the numerical simulation results. Consequently, the effectiveness of the established hysteretic model was verified. Compared with the cast-in-situ beam-column joint, PJ-CPH achieves the damage-free connection and exhibits the superior resilience performance. The simulation results suggest that self-centering ratio α values should be assumed approximately in the range 1.00–1.30, moment amplification factor β values in 1.30–1.40, which can induce damage to concentrate in controllable plastic hinge, protect the main structure from damage and reduce repair costs.

Experimental investigation of a novel reinforced concrete buckling-restrained brace

This paper describes an experimental investigation of a novel reinforced concrete buckling-restrained brace for precast concrete lateral load-resisting frame structures in seismic regions. The proposed brace uses ductile reinforcing bars with unbonded lengths across end gaps and bonded lengths at the middle region for lateral stiffness, strength, energy dissipation, and ductility. The experimental program included four isolated diagonal brace subassemblies subjected to reversed-cyclic pseudostatic lateral loading. Local buckling of the energy-dissipation bars across the end gaps is the most critical failure mode that can limit the ductility of the brace in compression. Up to this failure, the bonded and unbonded regions of the braces performed as designed. The results demonstrated the different deformation and stiffness behaviors of the braces in tension and compression. Subsequent loading to large tension displacements provided evidence of the large energy dissipation that can be expected if premature failure of the brace can be prevented. Simplified numerical models provided good predictions of the measured brace behavior until failure. This research featured the first set of tests for this brace, and the results highlighted adjustments needed to design and modeling to achieve the desired behavior of the brace. Recommendations for future research include improved shear dowel and confinement designs to prevent local buckling of the energy-dissipation bars and improved longitudinal reinforcement designs to prevent yielding of the energy-dissipation bars in the middle bonded region of the braces.

Beam torsion effect of monolithic precast concrete beam-column substructures during progressive collapse

To investigate the effect of spandrel beam torsion on the progressive collapse resistance of the monolithic precast concrete (PC) spatial frames, three PC substructures (a cantilever beam substructure PC-c, a double-span planar substructure PC-p and a spatial substructure PC-s) were designed. They were tested under a middle column removal scenario, to simulate the progressive collapse of the PC frame structures. The test results indicated that the torque developed in spandrel beams of the spatial substructure PC-s leaded to more severe concrete cracking and crushing at its beam ends. The existence of torque in the PC spatial substructure weakened the mobilization of compressive arch action (CAA) and catenary action (CA). The CA capacity of the spatial PC substructure was reduced by 27.23% compared with the planar substructure PC-p, and the CA action was ended in advance. Additionally, a three-dimensional joint model considering the torsion effect was proposed herein, which accurately captured the progressive collapse behavior of spatial substructures. Based on the verified numerical model, the difference between the combined torsion–bending interaction in the spandrel beam of planar and spatial substructures was analyzed. The effects of reinforcement configuration and span-depth ratio of spandrel beams on the collapse resistance were studied. Finally, a conservative calculation method of the increased gravity loads GN was given when the torsion effect needs to be considered.

A New Steel-Joint Precast Concrete Frame Structure: The Design, Key Construction Techniques, and Building Energy Efficiency

Assembled methods play a critical role in the construction of precast concrete structures. However, conventional dry-connections-like sleeve grouting joints in precast concrete structures lagged at a low construction and management efficiency with poor quality control. In this study, a novel steel joint for precast reinforced concrete beam-column components is proposed to improve constructability. New joints transform the assembled method from reinforced concrete members into a steel structure by setting a pre-embedded steel connector at both ends of reinforced concrete beams and columns, showing outstanding economic, durability, and fire resistance capabilities. The construction process, construction efficiency, economy, and energy consumption were discussed based on the material, structure, and construction hybrid characteristics. Numerical simulation and structural health monitoring methods are used to monitor and evaluate the deformation and stress state of the proposed system in the whole construction process, so as to optimize the construction scheme and ensure safe and orderly construction. The results reveal that the FEA-simulated values of key building components during construction are in good agreement with the actual monitoring values, which verifies the feasibility of the FEM models and provides a guarantee for construction safety; the construction period of the proposed assemble system is reduced by approximately 56% and 40%, compared with the conventional reinforced concrete frame structure and cast-in-place joints in the precast concrete frame structure, respectively. Meanwhile, the energy consumption of buildings decreases by 20%. This research provides a theoretical basis for the design, calculation, and application of assembled precast structural systems.

Experimental Study on Seismic Behavior of Precast Bolt-Connected Steel-Members End-Embedded Concrete (PBSEC) Beam-Column Connections

With the rapid development and research of precast concrete frame structures, it is not difficult to find that the structural form and seismic performance of dry-connected precast joints have always been the focus of research. Since this type of structural system is complex, the construction is inconvenient in practical application, and many additional parts need to be installed, this paper develops a kind of precast bolt-connected steel-members end-embedded concrete (PBSEC) beam-column connection to solve the shortcomings of the current dry-connected precast joints. There is no wet work in the assembly process, and all-dry construction and assembly methods are used. There is no need to pour concrete and support formwork, which significantly improves construction efficiency compared to wet and cast-in-situ connections. Low cyclic reversed loading tests were conducted to obtain test data, such as failure mode, hysteresis curve, skeleton curve, stiffness, ductility, and deformation capacity of the precast concrete joint. The failure mode of the PBSEC joints is the buckling failure of the connecting steel plate, leading to a perfect seismic capacity and collapse resistance of the structure. The hysteresis curves of the PBSEC joints are bow-shaped and full in shape, showing high energy dissipation capacity. The bearing capacity of the joints begins to rise rapidly at the initial loading stage and then decreases slowly after reaching the peak, which is an ideal shape. By summarizing the average peak load, strength degradation coefficient, loop energy per cycle, loop energy per level, and cumulative energy damping coefficient, it is found that the joint using 10 mm thick Q235 steel can obtain the most suitable failure mode and obtain the best energy dissipation performance. When the strength of the steel plate material increases, the energy dissipation performance of the joint drops.

Experimental and Numerical Analyses on the Seismic Performance of a Novel Precast Concrete Column-column Joints with Bolted End-plate Connection

To develop a precast concrete frame structure suitable for detachable design, a novel precast concrete column-column joint with bolted end-plate connection (BEPC) was proposed in this paper. To study the mechanical properties of the joint, three specimens involving one monolithic column (MC) and two precast columns (PC) with different joint position were tested by cyclic reversed loading at a certain compression ratio. The results show that the proposed joint has reliable seismic performance and the joint position has little impact on seismic performance. After the tests, these joints always kept linear elasticity under ultimate load, and were easy to disassemble, which met the requirement of detachable design. Finally, a fiber-based finite-element analysis model was developed to simulate the seismic behavior of this type of PC. The numerical results were verified by the experimental results. Then a parametric study based on the simplified model was conducted to research the effects of main structural factors on the seismic behavior of the joint.