Experimental and numerical investigation on flexural performance of non-prestressed concrete precast bottom slab with a removable section steel and three ribs

The enhanced loading capacity of transversely confined concrete deck slabs has been demonstrated through different studies, but the available transverse confining systems used in conjunction with cast in situ concrete deck slabs are not conducive to deconstruction. This paper presents the results of an experimental study on precast slabs attached to girders using bolted shear connectors. Ten half-scale precast slabs are tested under a monotonically increasing force applied at the mid-span. The configuration and proportion of the reinforcing steel bars and types of transverse confining system (cross-bracings or ties) are the main test variables. The experimental results demonstrate the efficiency of the proposed system for mobilising arching action in the precast concrete deck slabs. Also, it is shown that the location of reinforcing bars in single-span concrete slabs with transverse confinement can significantly influence the load capacity and ductility, but the top reinforcing steel bars have negligible influence on the peak load and ductility. In addition, detailed finite-element models of the specimens are developed and verified against test results and it is shown that the adopted finite-element models can adequately capture the local and global response of the transversely confined deconstructable precast concrete deck slabs.

Hollow-core precast concrete slabs are frequently employed in modular building construction to reduce concrete volume and weight. Nevertheless, the presence of the hollow-core increases susceptibility to failure. To address this issue, a composite reinforcing system (CRS) has been developed to support the void in precast slabs. This research aims to investigate the bending behavior of a composite slab comprising precast concrete, steel, and the composite reinforcement system. Bending tests will be conducted on precast slabs with various CRS configurations (including changes in tube material properties and tube cross-section) to assess the structural performance of this innovative construction system. Additionally, a non-linear finite element modeling was employed to gain a comprehensive understanding of the behavior of the internal components of the slab. The findings of this study will offer valuable insights for designing more reliable and cost-effective hollow-core precast concrete slabs.

Methods for the vibration analysis of reinforced concrete precast one-way joist slab floor systems under human walking

Steel — Concrete Composite Construction with Precast Concrete Hollow Core Floor

The joints of precast splice slabs significantly impact their flexural bearing capacity. This paper introduces a novel type of precast splice slab, termed the precast concrete splice slab with welded junction plates. A flexural loading test was conducted on 10 specimens (including eight precast splice slabs, one precast slab, and one cast‐in‐place slab). The main conclusions of the test are as follows. Severe damage barely occurred at the joint and at the interface between the precast unit and the cast‐in‐place concrete. The specimen produced flexural type vertical cracks in the tension zone and transverse cracks in the compression zone. When some longitudinal rebars in the precast unit of the specimens were bent into an arc, the cracking and yield loads were lower than those of the ordinary precast or cast‐in‐place slabs. The incorporation of lap‐splice rebar in the cast‐in‐place concrete improved only the yield load of the specimens, while the welding of additional rebar in the precast unit significantly enhanced both the cracking and yield loads. A design method for determining the flexural bearing capacity of the precast concrete splice slab with welded junction plates was established. Meanwhile, the force transfer mechanism of the junction plates needs to be further investigated to establish a more economical design method for the junction plates.

This article proposes a new type of discrete connected precast reinforced concrete diaphragm floor system that consists of precast flat slabs and slab joint connectors. An experimental investigation of discrete connected new-type precast reinforced concrete diaphragm under a vertical distributed static load was conducted, and the effect of slab joint connectors on the load-bearing capacity was evaluated. Then, a finite element analysis of discrete connected new-type precast reinforced concrete diaphragm, precast reinforced concrete floors without slab connectors, and cast-in-situ reinforced concrete floor were performed to understand their working mechanism and determine the differences in load-bearing behavior. The results indicate that the load-bearing capacity and stiffness of discrete connected new-type precast reinforced concrete diaphragm increase considerably as the hairpin and cover plate hybrid slab joint connectors can efficiently connect adjacent precast slabs and enable them to work together under a vertical load by transmitting the shear and moment forces in the orthogonal slab laying direction. The deflection of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction is mainly caused by the opening deformation of the slab joint and the rotational deformation of the precast slabs. This flexural deformation feature can provide reference for establishing the bending stiffness analytical model of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction, which is vitally important for foundation of the vertical bearing capacity and deformation calculation method. The deflection and crack distribution patterns infer that the discrete connected new-type precast reinforced concrete diaphragm processes the deformation characteristic of two-way slab floor, which can provide a basis for the theoretical analysis of discrete connected new-type precast reinforced concrete diaphragm.

Full-scale push-out testing of headed stud-steel block connectors in prefabricated steel-concrete composite beams

Precast concrete composite slab is one of the most widely used precast elements in civil engineering, which is suitable for all kinds of prefabricated concrete structure. The longitudinal bars at the bottom of precast slab extend beyond the ends of it, which brings a lot of inconveniences in fabrication, transportation and installation. In order to avoid those disadvantages of traditional precast concrete composite slab, a new no-protruding rebar concrete slab shear wall joint is developed in this paper. And five concrete slab-shear wall joint specimens were fabricated to research the joint structure of composite slab with no-protruding rebar but including additional rebar. In order to verify the seismic performance of the new concrete slab-shear wall joint, Pseudo-static testing of those specimens were carried out and the bearing capacity, stiffness, ductility and energy-dissipating capacity of different specimens were compared. The experiment results show that the additional rebar is necessary to the joints of composite slab with no-protruding rebar shear wall to ensure the seismic reliability of the joint connection; the bearing capacity and ultimate deformation of the new no-protruding rebar concrete slab-shear wall joint increase with the increasing of the lapped length of additional rebar.

Experimental study of composite beams having a precast geopolymer concrete slab and deconstructable bolted shear connectors

Bending behaviour of precast concrete slab with externally flanged hollow FRP tubes

It is known that the prestressed half PC (precast) slab system has many advantages such as a reduced construction period and use of long-span one-way slab systems over reinforced concrete and half PC slab systems without prestressing. For this reason, prestressed half slabs are commonly used for both residential and basement parking structures in Korea and other countries. The prestressed half PC slab systems currently being used only have the pre-tensioning system only for PC slabs. To ensure better performance of the half PC slab system with larger span-to-depth ratio, a new system using both pre-tensioning and post-tensioning methods is suggested for basement parking structures in this paper. The main purpose of this paper was to analyse the suggested model and verify its safety and serviceability for a given span and a given load. The second purpose is to suggest a preliminary calculation process for the suggested system that satisfies the ACI 318 requirements. A parametric study is conducted in order to find the best and most economic model using four variables: (1) depth of precast concrete; (2) depth of topping concrete; (3) number of pre-tensioned tendons; and (4) number of post-tensioned tendons. The obtained model satisfies the requirements of ACI 318 in terms of working stress design.

The connection zones between precast concrete composite slabs and composite walls commonly experience severe reinforcement conflicts due to protruding rebars, significantly reducing construction efficiency. To address this, a novel slotted concrete composite slab–composite shear wall (SCS-CW) connection without protruding rebars is proposed in this study. In this novel connection, rectangular slots are introduced at the ends of the precast slabs, and lap-spliced reinforcement is placed within the slots to enable force transfer across the joint region. To investigate the static performance of SCS-CW connections, four groups of connection specimens were designed and fabricated. Using the structural detailing of the connection zone as the variable parameter, the mechanical performance of each specimen group was analyzed. The results show that the specimens demonstrated bending failure behavior. The key failure modes were yielding of the longitudinal reinforcement in the post-cast layer, yielding of the lap-spliced reinforcement, and concrete crushing at the precast slab ends within the plastic hinge zone. Compared to composite slab–composite wall connections with protruding rebars, the SCS-CW connections demonstrated superior ductility and a higher load-carrying capacity, satisfying the design requirements. Additionally, it was revealed that the anchorage length of lap-spliced reinforcement significantly affected the ultimate load-carrying capacity and ductility of SCS-CW connections, thus highlighting anchorage length as a critical design parameter for these connections. This study also presents methods for calculating the flexural bearing capacity and flexural stiffness of SCS-CW connections. Finally, finite element modeling was conducted on the connections to further investigate the influences of the lap-spliced reinforcement quantity, diameter, and anchorage length on the mechanical performance of the connections, and corresponding design recommendations are provided.

Experimental and numerical investigation on flexural behavior of non-prestressed concrete precast bottom slab with a section steel and two ribs

In recent years, composite slabs have been extensively adopted in diverse structural systems owing to their superior construction efficiency, exceptional structural integrity, as well as reliable fabrication with consistent quality assurance. Compared to traditional cast‐in‐place slabs, precast slabs require notably less formwork. However, due to the insufficient out‐of‐plane stiffness of precast slabs, the fabrication of conventional composite slabs still relies heavily on bottom support systems, a process that is both labor‐intensive and time‐consuming. To address the aforementioned issues, a novel type of reusable additional double channel steel stiffener (ADCSS) is proposed to temporarily enhance the out‐of‐plane stiffness and crack resistance of precast bottom slabs during the lifting, transportation, and construction stages. The ADCSSs are installed beneath the slabs and are effectively connected to the slabs by specially designed spring connection joints. Based on the bending mechanism of unbonded composite beams, this study proposes a comprehensive stiffness‐based design method for the ADCSS. To verify the reliability of the proposed design method and the effectiveness of the ADCSSs, three full‐scale precast bottom slabs equipped with ADCSSs were fabricated and tested. Under construction loads, the mid‐span deflections of the three specimens did not exceed l/200 (9.5 mm for OBS‐1 and 14.5 mm for PBS‐1 and PBS‐2, respectively), all below the allowable limit. The maximum difference between the measured and theoretical cracking loads was less than 13%, confirming the validity of the design approach and the satisfactory performance of the ADCSSs during the construction stage. A refined finite element model was developed using ABAQUS software to systematically investigate the failure mode of the precast bottom slabs with ADCSSs. It was also used to examine the influence of various parameters, including flange width, thickness, and the cross‐sectional height of the channel steel, on the stiffness and load‐carrying capacity of these precast bottom slabs. The results demonstrate that the proposed innovative ADCSS not only enables precast bottom slabs to meet the requirements of load‐carrying capacity and crack control, but also offers significant advantages in production, transportation, and construction stages.

Nowadays there are several kinds of products innovations in the construction industry, one of whom is a precast concrete slab. In fact, products of innovation are not necessarily fully able to provide a positive impact, both in terms of cost, quality, time, and waste on building construction projects. Moreover, what is offered by the manufacturer of precast concrete slab has not necessarily correspond with the needs of the customer. The purpose of this study is to analyze the comparison of products in terms of time, cost, quality, and waste between projects using precast concrete slab and the same projects that were simulated using floordeck concrete slab. This research will: (1) simulate the project if not using precast concrete slab product, (2) analyze the comparison of products in terms of time, cost, quality, and waste between the real project and the simulation project, (3) calculate the benefits obtained from the use of precast concrete slab product. The use of flyslab at Pertamina Parking Building Project (which consists of three floors and two floors using flyslab) when compared with the results of the simulation project that uses floordeck concrete slab: (1) in terms of time, it can provide a savings of 12.5% of the total duration of the simulation project, (2) in terms of costs, it can provide costs savings on the total cost structure reaches 23.13%, (3) in terms of quality, flyslab constituent materials are designed to have a higher quality when compared to floordeck concrete slab constituent materials, (4) in terms of waste, on a project that uses flyslab, the amount of waste generated is much less when compared to the results of the simulation project that uses a floordeck concrete slab.