Precast Structures Research Articles

Seismic performance of precast column-beam joint with artificial plastic hinge

To improve the seismic performance and repairability of precast structures, an artificial plastic hinge (APH) was proposed for precast beam-column joint. The proposed APH was made from a combination of steel and high-strength-concrete (HSC), and the AHP will dissipates energy through metal plastic deformation when the earthquake occurs. To carry out the research, three full-scale beam-column joints were designed and fabricated, including one cast-in-place joint and two precast joints with APH. By using hysteretic loads, the seismic performance of joint was examined. For more systematic research, the finite element models were established and verified, and the parameter analysis was carried out. The findings demonstrate that the proposed joint performs well in terms of ductility and energy dissipation. It is recommended to use 12 mm steel plate thickness in the actual design, and to ensure the number of connecting bolts to avoid connection damage under earthquake. Through design optimization, the damage to the APH will be revealed at the location of the replaceable steel components, so as to achieve rapid repair after the earthquake.

Failure analysis of monolithic precast shear wall structure subjected to strong earthquake

In recent years, the risks of natural (earthquakes) and artificial (terrorist attacks) disasters to buildings and communities have attracted increasing attention. On the other hand, an increasing number of prefabricated building structures have been constructed in urban areas of China owing to the promotion of the government. The failure behaviours of prefabricated building structures subjected to disastrous actions have not been thoroughly investigated and understood. Therefore, in this study, we have established a finite element model of the monolithic prefabricated structure. A damage plasticity model was introduced to describe the failure of concrete materials and critical members of the structure. Using the failure criterion and element deletion techniques, the overall failure of the structure in the pattern of total collapse was obtained. The analytical results showed that effective vertical connections can improve the collapse resistance of prefabricated structures. The simulation results verified the proposed method and provided new insights for the anti-collapse design of monolithic precast structures.

FE analysis of pulled-out eccentrically spliced longitudinal headed bars for precast beam-footing connections

ABSTRACT Load transfer in structural elements of RC constructions and the behavior of such constructions are basically dependent on the detailing of both the structural elements and their connections. Assessing analytically the characteristics and behavior of such structural elements and their connections under likely occurring loads is an important issue. For common detailing of footings in steel and precast structures, longitudinal reinforcement of foundation beams is bent horizontally and spliced with reinforcement of cast-in-place footings to insure an adequate juncture for load transfer. In this study, as concerned with reducing construction time and cost, instead of bending longitudinal reinforcement bars of both, beams and footings, headed reinforcement bars are adopted. By doing so, a discontinuity region is created where longitudinal bars of footings become eccentric to those of beams that are embedded in the footings. To allow the flow of tensile forces from longitudinal bars of beams to longitudinal bars of footings, a set of reinforcing ties is provided between them. As such setting of headed reinforcement bars is not common, thorough investigations have been carried out to confirm the relevance of the proposed tie reinforcement. In this paper, results of a finite element numerical investigation of pulled-out eccentrically spliced longitudinal headed bars with different detailing of transverse reinforcement, proposed for precast beam-cast-in-place footing connection, are presented and compared to test results. The elaborated modeling could fairly reproduce the global behavior of the six specimens, where the numerical results acceptably approached the experimental results in terms of initial stiffness, ultimate strength, crack pattern and strain of reinforcement.

Experimental study on joint’s seismic performance of a PCSW with thermal insulation elements

Precast coupled shear walls with thermal insulation elements (PCSW-T) are structurally and thermally efficient systems, which are deemed promising in precast structures. Nevertheless, the beam-wall joint may still function as a weak region during seismic events, which remains a fraught issue. In this paper, an innovative connection using double-section mechanical sleeve (DMS) systems was presented and investigated experimentally. Two monolithic and four PCSW-T joint specimens, evenly divided into two groups, were tested under reversed cyclic and pushover loadings, with beam shear-span ratios of 2.5 and 0.75, respectively. Experimental results revealed that the PCSW-T joints displayed similar damage modes to the monolithic ones under different shear-span ratios, while their seismic behaviors in terms of strength, deformation, stiffness, ductility, and energy dissipation were even better. Consequently, the PCSW-T structure can fulfill the design criterion of “equivalent to cast-in-place”.

Seismic Risk and Finite Element Modelling Influence of an Existing One-Storey Precast Industrial Building

ABSTRACT Precast structures are widely used in Southern Europe particularly for industrial buildings. Most of such buildings have been built before the enforcement of modern anti-seismic regulations showing a poor performance during past major earthquakes. Focusing on existing one-storey precast industrial buildings, the paper investigates the influence of modelling choices on the risk assessment, direct losses, and required structure retrofit time. RC forks, cladding panels, and elements connections were specifically considered. A precast industrial building with structural details compatible with 1980s Italian regulations was selected and analysed. In general, the failure was associated with the collapse of roof elements.

Behavior of Confined Headed Bar Connection for Precast Reinforced Concrete Member Assembly

The mechanical performance of precast RC structures relies on the connections, especially the connections of steel bars, between precast RC members. Grouted sleeve splices and grouted spiral-confined overlap connections are widely used in engineering practice in China. Both of these two connection splices require on-site grouting. The process is concealed and invisible, leading to difficult on-site inspection. The unseen defects cause a challenge for detection and repair, which may impair the reliability of precast RC members’ behavior. This paper presents an RC member assembly connection with visible on-site construction quality-monitoring. The proposed confined headed-bar connection (CHBC) consists of two overlapping headed bars and confinement stirrup. With CHBC, the potential construction defects are diminished, and subsequently the construction quality as well as the reliability is upgraded. Experimental investigation on 18 CHBC specimens was carried out; the main parameters considered were overlap length and bar-head size. The failure modes, bearing capacity, stirrup strain development and bond versus slip response are studied. Working mechanism of CHBC is investigated in terms of bond behavior force and concrete compression force at head experimentally and numerically; distributive relationship of these two forces is revealed. The results show that for Φ12 reinforcement, a 90 mm overlap length under test parameters is adequate to reach headed bar ultimate strength in CHBC. Finally, a CHBC-bearing capacity prediction method is suggested based on the superposition method and strut-and-tie model theory.

Multi-hazard vulnerability for single-walled full-assembled underground stations

Full-assembled underground station (FUS) uses precast single-walled structure replacing traditional double-walled structure with overlapping diaphragm and exterior walls. The vulnerability of single-walled FUS against the urban multi-hazard factors is a critical unresolved problem. To fill this knowledge gap, this study proposed a single-walled FUS (FUS-1 W) multi-hazard vulnerability function for its first application in Shenzhen Metro. First, a full-scale test was performed on the precast single-walled structure. Second, multi-hazard finite element analysis (FEA) was performed for FUS-1 W and double-walled prefabricated underground station (PUS-2 W). Third, the vulnerability functions were constructed. The main conclusions include the following: (1) The test showed that the single-walled structure has significant performance recovery capability. (2) FEA results indicated multi-hazard effect was about 20 % higher than single-hazard. The deformation inclusiveness of FUS-1 W were twice of PUS-2 W in top and foundation zones, whereas it decreased to 50 % in structure zone. (3) The minor-damage probability of FUS-1 W were 23–36 % lower than that of PUS-2 W in top and foundation zones, whereas it was 28 % higher in structure zone. It is suggested that FUS-1 W be monitored to avoid aggravating damage and construction hazard should be closely monitored to alleviate the multi-hazard superposition effects. The research provide quantitative evaluation for the security management of single-walled FUS and have important application value for the promotion of FUS.

Shaking table tests and seismic assessment of a full-scale precast concrete sandwich wall panel structure with bolt connections

A novel, light-weight, sustainable, repairable and cost-effective precast concrete sandwich wall panel structure system is proposed in this paper, including the dry bolt connections and the precast concrete sandwich panels. To evaluate the seismic performance of precast structure system, a sequence of shaking table tests is carried on the full-scale precast concrete sandwich wall panel structure, and the dynamic characteristics, damage pattern, dynamic responses and seismic fragility are investigated and analyzed by the test results under service level earthquake, design based earthquake, and maximum considered earthquake. The seismic fragility curves and failure probability curves are analyzed by the shaking table test results, which quantitatively describes the seismic performanceexpressed by probability. The results show that the precast concrete sandwich wall panel structure performs high lateral stiffness, large safety margins and high strength reserves. The precast concrete sandwich wall panel structure system presents a good seismic performance. The damage of the structure is slight under maximum considered earthquakes, and the structure has begun to enter the plastic stage. The light-weight characteristic reduces the dynamic responses, and the mild sliding between precast components consumes a fraction of seismic energy.

КОНСТРУКТИВНАЯ СИСТЕМА БЫСТРОВОЗВОДИМОГО ЗДАНИЯ ИЗ ИНДУСТРИАЛЬНЫХ ПАНЕЛЬНО-РАМНЫХ ЭЛЕМЕНТОВ

The paper presents a new structural solution of the precast-monolithic frame for prefabricated residential and civil buildings of various storeys manufactured from prefabricated industrial reinforced concrete elements. The precast frame structures include L-shaped and inverted U-shaped precast elements, installed in the longitudinal and transverse directions and forming a frame, hollow-core slabs and bracing perforated beams of the outer contour, on which fencing non-bearing wall structures are supported within each storey. The computational model of the precast-monolithic building frame was developed using different degrees of discretization at different stages of the analysis. This allowed to obtain both a general picture of structural system deformation in the limiting and over limit states caused by special and emergency actions, and a detailed picture of the stressed state in concrete and reinforcement of structural elements before and after cracking. The paper provides the results of the comparative analysis of the effectiveness of application of the proposed structural system in the mass construction as compared with the applied constructions of large-panel buildings. It has been shown that the application of the proposed structures of panel-frame elements allows considerably reduce the material capacity, cost and transportation expenses of the reinforced concrete frame by up to 30 %, ensuring the mechanical safety of the building.

Cyclic response of precast concrete columns connected with cast-in-place UHPC in plastic hinge region

Ultra high performance concrete (UHPC) is a promising material for lap splice connection of steel bars in reinforced concrete (RC) precast structures given its high compressive strength, its high toughness, and its high bond strength with steel bars. This paper focuses on the cyclic response of bottom frame columns connected by UHPC in the plastic hinge region. The effect of lap length of longitudinal bars in UHPC (6d, 8d and 12d, d = diameter of longitudinal bar), axial load ratio and stirrup ratio of the UHPC connection region on the global response of the columns were presented and analyzed, and a cast-in-site RC column was prepared for comparison. The behavior of the UHPC connected columns was flexural dominated, but columns with 6d and 8d lap length failed due to the gradual bonding degradation between UHPC and longitudinal bars, and the column with 12d lap length failed due to UHPC crushing. It was demonstrated that a 8d lap length could achieve equivalent lateral bearing capacity and ductility to the control RC column, but the lap length should be greater than 8d when applying UHPC connection technology in seismic regions to ensure the energy dissipation. Column with lower axial load ratio (0.17) exhibited lower ductility because shear sliding occurred between the interface of UHPC and footing at the post-peak stage. The UHPC connected specimens exhibited higher resilience and better damage resistance in earthquake because the ratios of the residual displacements to the corresponding peak displacements were between 17 and 39%. Besides, a flexural capacity model for the columns was developed and the results predicted by the model agreed well with the experimental results.

Behaviour of non-ballast pre-stressed and precast track structures in high speed railway based on multiscale finite element model

In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures, which was self-designed in China, based on the method of the multiscale finite element model (FEM), the traditional FEM of slab non-ballast track structures was improved. The multiscale FEM of CRTSIII type slab non-ballast track structures was established based on the general finite element program ABAQUS. Then the comparative calculation was made between various FEMs, showing that the high solution precision, fast modelling speed and high solution efficiency could be obtained. Therefore, the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSIII type slab non-ballast track structures, and then the key influence factor and constructions could be optimized.

Experimental study on a dry-assembled precast concrete frame with buckling-restrained braces

This paper proposes a new dry-assembled precast concrete frame with buckling-restrained braces (BRB-DPCF) to reach the full potential of building industrialization and promote the popularization of precast structures in earthquake-prone zones. A new mechanical coupler and an unbonded posttensioning (PT) technology were adopted for the column-to-column joint and beam-to-column joint, respectively, of the BRB-DPCF. In this paper, the authors designed and tested a monolithic concrete frame with buckling-restrained braces (BRB-MCF) and a BRB-DPCF to investigate the seismic performance of the BRB-DPCF. The two specimens were two-story, single-bay concrete frames with a story height of 1750 mm and a bay of 2500 mm. The test results demonstrated that the BRB-DPCF exhibited stable and fat hysteretic loops and a lateral-resistance capacity comparable to the BRB-MCF. The BRB-DPCF showed a greater initial stiffness and smaller energy dissipation capacity than the BRB-MCF. The column damage of the BRB-DPCF was similar to that of the BRB-MCF, while the girder damage of the BRB-DPCF was negligible compared with that of the BRB-MCF. The BRB-DPCF featured a greater repairable ability after earthquake events than the BRB-MCF.

Test and Bearing Capacity Calculation of a New Energy-Dissipated Precast Shear Wall

At present, most precast shear walls are implemented in accordance with the method equivalent to a cast-in-place structure, where the joint is complicated, and the construction is difficult. According to the characteristics of precast shear wall structures, the design method of “strong horizontal joints, weak vertical joints” for a precast shear wall structure is proposed. The existing horizontal joint method was used to form strong horizontal joints, and the damper was used to connect the vertical joints to form weak vertical joints. It can reduce the pouring of concrete and improve construction efficiency. Three types of specimens (Rectangle shape, T shape, L shape) were designed. Low cycle reciprocating load tests were carried out under different axial compression ratios (0.1, 0.3), and the bearing capacity and ductility of the specimens were studied. The results show that the precast shear wall structure has good mechanical properties. The ductility coefficient is close to or greater than three, and the maximum ductility coefficient is 3.62. The specimens have good ductility. The relative displacement of the damper is greater than 1.75 mm. All the dampers yield and dissipate energy, which improves the seismic performance of the structure and plays a good role in connecting the wall limbs. The strain distribution law of the specimen section is discussed, the simplified mechanical calculation model is given, and the calculation method of flexural capacity of a precast shear wall structure is put forward.

Monitoring Precast Structures During Transportation Using A Portable Sensing System

During the delivery process, precast concrete structures (PCS) undergo drastic changes in strain response that could induce damage resulting from the lifting process or shocks during delivery. However, the continuous logging of vibration and strain measurement during the delivery of a PCS remains limited because of difficulties related to sensor installation and condition assessment. This paper presents (1) a multimetric portable sensing system that simultaneously measures strain and acceleration, and (2) a safety assessment strategy that adjusts the offset of the initial strain measurement and calculates the absolute strain response for assessing the safety of PCS during the delivery process. The experimental validation was performed during the 80-min delivery process of a 12-m-long PCS. The acceleration, tilts and strain of the structure were measured during its delivery, and the measured data were processed and analyzed to conduct a safety assessment.

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.

Progressive collapse fragility of substandard and earthquake-resistant precast RC buildings

Several natural and man-made disasters have highlighted that precast reinforced concrete (RC) buildings often have insufficient levels of structural robustness, which is the last line of defence under extreme events. Even though robustness studies were originated by the progressive collapse of the Ronan Point precast RC building in 1968, such a structural feature of disaster resilience has been partially investigated in case of precast RC buildings to date. In this study, a precast RC frame structure representative of low-rise commercial buildings is analysed under different column loss scenarios, which can produce the partial or total collapse of the structural system. Two building classes are considered, namely, buildings designed only to gravity loads and buildings designed for earthquake resistance. Structural robustness is probabilistically assessed through a fragility analysis procedure, using three-dimensional fibre-based finite element models with nonlinear links simulating connections, large-displacement incremental dynamic analysis, and multiple performance limit states for damage assessment. The output of the study is threefold: (i) a detailed assessment of the effects of column loss on precast RC frame buildings, quantifying the major role of structural detailing and beam-column connections; (ii) a fragility-informed evaluation of beneficial effects of seismic detailing on structural robustness, which can drive designers in retrofitting of existing precast RC buildings and decision-makers towards prioritization-related issues; and (iii) the generation of typological fragility curves for progressive collapse risk assessment in both single- and multi-hazard environments. Progressive collapse fragility curves can be convolved with more classical fragility models describing the failure of single components (under, e.g., flow-type landslide impact, vehicle collision or blast) and hazard, to assess systemic structural risk.

The Comparative Study of the Development on Prefabricated Construction

Prefabricated construction is one of the most intensively developing areas of research in the field of construction and building technology in the world. The results of the scientometric analysis prefabricated construction are presents in this paper. The purpose of the scientometric analysis was to study the directions and effectiveness of research, to determine the leading countries, organizations, scientific journals, to define the level of prefabricated construction in the Republic of Belarus in the context of economically developed countries. The scientometric analysis was carried out in the analytical system SciVal with the use visualization tools, quantitative and qualitative scientometric metrics. Growth of the number of publications in the field of prefabricated construction and indicators of analyzed scientometrics metrics confirms the fact that prefabricated construction attracts more and more researchers all over the world and is a promising direction of scientific research. Determined that design and informational modeling, organization of construction and precast structures production, delivery of structures to the construction site and their assembly, including reliability, efficiency, environmental friendliness of prefabricated construction are main topics in the field of prefabricated construction. At the same time, topics in the field of research of technologies and organization production of reinforced concrete elements in plant, production management are given less attention, which requires further research in these areas. The results of the scientometric analysis allow us to identify trends, determine priority areas for further research and their connection with other fields of science, and can be a scientific basis for identifying data gaps in current research in the field of prefabricated construction.

Nonlinear numerical modeling approach and seismic mechanism analysis on new modular precast composite shear wall structure

An innovative modular precast composite shear wall structure with the advantages of modular precast construction and demountable ability was proposed, and its seismic performance was validated by shaking table tests. This study aims to develop a nonlinear numerical modeling approach for the innovative modular precast structure to promote its engineering application. An equivalent energy method for the overall backbone of the concrete constitutive relationship was derived to consider the concrete stiffness reduction in the numerical model. Based on sectional analysis and plane section assumption, an explicit equivalent joint model was developed to simulate the nonlinear behavior and failure process of the vertical joints. Comparisons between the numerical and test results validated the ability of the numerical model to capture both the global and local responses. More detailed results that were hardly obtained by tests, such as displacement components, joint mechanical state and gap opening behavior, were extracted from the numerical analysis to reveal the seismic mechanism of the modular precast structure. The dynamic analysis results showed that the vertical joint deformation induced 10% to 14% of the total inter-story displacement at the first floor within the maximum considered earthquake intensity. The equivalent joint model could simulate the failure process of individual screws which exhibited larger strains than those in shear walls. The gap opening behavior induced additional energy dissipation mechanism for the modular precast structure.

Flexural Behavior of Precast RC Deck Panels with Cast-in-Place UHPFRC Connection

Precast concrete bridge structures have been extensively used because of the mature construction techniques, fast construction, and their economy. Considerable practical applications, however, present certain disadvantages, such as cracking and water infiltration in their normal strength concrete (NSC, compressive strength 40 MPa) joints connecting prefabricated deck panels. Ultra-high performance fiber reinforced concrete (UHPFRC, compressive strength 143 MPa) has been proven highly effective in replacing the conventional cementitious grout materials in precast bridge structures. In the present study, three types of UHPFRC connections, rectangular, zigzag-shaped, and diamond-shaped, were experimentally evaluated on their flexural capacities, interface bonding performances, and failure modes through four-point bending tests (loading rate 0.1 kN/s). The results showed that all the UHPFRC connections exhibited apparently higher flexural capacities than an intact precast NSC member and had such strong UHPFRC-NSC interfacial bonding that the interfacial first-crack strengths were not less than the NSC member. Having the capability of modeling the UHPFRC connections and their interface properties, the developed finite element (FE) models of the precast slabs with UHPFRC connections produce numerical results in good agreement with the flexural tests. By means of the FE models, parametric investigations were carried out to make suggestions on optimizing the UHPFRC connection designs for practical use.

Experiment Study on the Hysteretic Performance of a Novel Replaceable Beam-to-Column Joint with Energy-Dissipating Steel Hinge

A novel precast replaceable beam-to-column joint with energy-dissipating steel hinges was proposed for the connection of precast structures to improve the seismic performance and post-earthquake resilience. The proposed joint was installed in the predetermined plastic hinge region at beams and the flange segments of the proposed joint were weakened to achieve damage concentration. Cyclic loading tests were conducted on the proposed joint and the steel sleeve confined concrete joint to study the hysteretic performance, including failure mode, load–displacement curves, ductility, and energy-dissipation capacity. Moreover, the hystertic performance of the damage-repaired proposed joint was investigated to verify the post-earthquake resilience. Results demonstrated that the proposed joints could develop favorable failure mode with the necking rupture of the weakened steel plate in steel hinge. The damage of the proposed joint was concentrated in the energy-dissipating hinges while no serious damage was observed in the precast framing components, achieving the objective of damage concentration. Compared with steel sleeve confined concrete joint, the hysteresis curve of proposed joint was more plump while an obvious pinching effect was observed in the steel-confined concrete joint. The bearing capacity and energy-dissipation capacity of the proposed joint were about 1.25 times and 1.55 times of that for the steel sleeve confined concrete joint, respectively. In addition, the hysteretic performance of the repaired specimen was identical to the original one, with the desired failure mode caused by the fracture of the steel hinge. It was noted that the hysteretic performance of the repaired joint was better than the steel sleeve confined concrete joint. The bearing capacity was recovered at up to 96.6% of the original joint while the energy-dissipation capacity was recovered at 96.1%, indicating that the proposed joint achieved the post-earthquake resilience to a great extent.