One-way Slabs Research Articles

Flexural Behavior of Thin Concrete Slabs Reinforced with Surface Embossed Grid-Type Carbon-Fiber Composites

Fiber-reinforced polymers (FRPs) are being increasingly used to replace rebars as reinforcements for concrete. In this study, the flexural behavior of one-way concrete slabs reinforced with a grid-type carbon FRP (CFRP) (carbon grid), in the form of strands with embossed surfaces, was experimentally investigated. The experimental variables included the effective depth, number of carbon grid layers, and concrete compressive strength. The results exhibit that the surface embossing of the CFRP strands effectively improves their bonding with concrete based on the crack formation pattern. Concrete specimens reinforced with carbon grids exhibited an increased maximum load and stiffness as the effective depth, number of carbon grid layers, and concrete compressive strength increased. Among the experimental variables, the effective depth exhibited the greatest influence on the flexural behavior of the carbon-grid-reinforced concrete specimen. Furthermore, the ratios of the experimental to calculated flexural strength values for all carbon-grid-reinforced concrete specimens ranged from 0.74 to 1.22. Based on the results, a trilinear load–deflection curve was proposed to simulate the flexural behavior of carbon-grid-reinforced concrete members, considering the bond property between the concrete and the carbon grid. The proposed trilinear load–deflection curve reasonably simulated the flexural behavior of the specimens reinforced with carbon grids.

Shear Strength of Steel Fiber-Reinforced Concrete Beams and One-Way Slabs

Shear Strength of Steel Fiber-Reinforced Concrete Beams and One-Way Slabs

Residual flexural performance of large-scale ferronickel slag alkali-activated concrete slabs after fire exposure

Background This study explores the flexural behavior of unfired and fired one-way slabs constructed from reinforced ferronickel slag-based alkali-activated concrete (AAC). Despite growing interest in AAC as a sustainable alternative to ordinary Portland cement (OPC), limited research exists on large-scale structural elements, particularly under post-fire conditions. Methods Four slabs (2.1 × 0.9 × 0.18 m3) were tested: two made of AAC and two of OPC concrete with comparable compressive strengths. In each group, one slab served as a reference and was tested under monotonic four-point bending in its original state. The other was exposed to a standard fire curve on the tensioned side, then cooled to ambient conditions before mechanical testing. Additional analyses, including mercury intrusion porosity (MIP) and scanning electron microscopy (SEM), were conducted to evaluate fire-induced microstructural changes in the AAC slabs. Results The AAC slabs demonstrated a load capacity 6% lower than OPC slabs. However, AAC slabs exhibited better post-fire retention of stiffness and ductility. Microstructural analysis revealed increased porosity and microcracking in AAC after fire exposure, which influenced its mechanical performance. Conclusions The results suggest that ferronickel slag-based AAC can provide comparable performance to OPC concrete in flexural applications, with enhanced retention of stiffness and ductility after fire exposure. These findings support the viability of AAC for structural applications while highlighting its resilience under post-fire conditions.

Out-of-plane shear behavior of BFRP-reinforced geopolymer concrete one-way slabs: Experimental and numerical investigations

Sustainability and durability in construction are vital considerations that involve using environmentally friendly materials and implementing efficient design and construction techniques to minimize the environmental impact. This research study investigated the structural behavior of one-way solid slabs incorporating basalt fiber-reinforced polymer (BFRP) reinforcement and geopolymer concrete to develop an environmentally sustainable and durable structural member. Six full-scale BFRP-reinforced geopolymer concrete one-way slab specimens were prepared and subjected to four-point loading tests to assess their out-of-plane shear performances. The considered experimental parameters were compressive strength of concrete (i.e., 30, 40 and 50 MPa) and longitudinal tensile reinforcement ratios (i.e., 1.20% and 2.18%). The structural performance of the slabs was carefully investigated in terms of crack patterns, failure modes, load-deflection relationships and load-strain relationships. The obtained shear resistances from tests were compared with predicted results from the Codes of Practice and design guidelines. A two-dimensional (2D) finite element (FE) analysis was conducted, considering the bond-slip relationship between BFRP rebar and geopolymer concrete. It was found that all tested specimens were governed by shear failure and had similar shear resistance for the chosen values of considered parameters. The JSCE shear design method provided the closest prediction of shear resistance of BFRP-reinforced geopolymer concrete one-way slab. The developed FE models predicted the out-of-plane shear performance with reasonable accuracy and revealed that the slip distribution of the BFRP rebar presents a sawtooth shape owing to concrete cracking.

Effective Moment of Inertia of Reinforced Concrete and Reinforced Steel Fiber-Reinforced Concrete One-Way Slabs

Effective Moment of Inertia of Reinforced Concrete and Reinforced Steel Fiber-Reinforced Concrete One-Way Slabs

Key effects on the structural behavior of fiber-reinforced lightweight concrete-ribbed slabs: A review

Abstract A concrete slab is one of the chief structural members in buildings, considered the most prominent member consuming concrete. Structural engineers are challenged to work on the new trend introduced using different slabs. One-way ribbed slabs are commonly used in construction due to their efficiency in spanning long distances while maintaining a low overall depth and giving the least possible number of columns. The main limitation of slab design in the construction of a reinforced concrete structure is the span between columns; a greater span between columns necessitates more supported beams or increased slab thickness; these requirements lead to an increase in the structure weight due to other concrete and steel which make the structure more costly. On the other hand, any increase in the structure’s self-weight limits the horizontal slab’s span, increases the structure’s stress, and raises the inertia forces that must be resisted. Lightweight aggregate concrete has been effectively utilized for structural applications for a long time. The density of lightweight concrete (LWC) is sometimes more essential than its strength in structural applications. The dead load is reduced for structural design and foundations when the density is lower for the same strength level. Reinforced concrete ribbed slabs have become increasingly popular in industry construction as an alternative to solid slabs in building structures. The incorporation of steel fibers facilitates flexural softening, which takes longer than sudden brittle failure, indicating its ability to increase energy absorption and improve crack behavior. Designing structures requires materials with higher strength-to-weight ratios. Ribs and LWCs are two leading sustainable assets. The world is moving toward sustainability by reducing the amount of concrete used and the overall weight of the unit. Studies have shown that the drop in compressive strength was about 4.85–65.55%. The structural performance of lightweight fiber-reinforced concrete slabs is influenced by the concrete mix ratio, fiber type and content, reinforcement detail, and rib geometry. The study provides valuable insights into the properties and performance of key effects on the structural behavior of fiber-reinforced LWC-ribbed slabs. It provides recommendations for future research and advancement of sustainable building methods.

Load transfer behavior of 3D printed concrete formwork for ribbed slabs under eccentric axial loads

3D printed concrete (3DPC) has primarily been used for non-structural applications, with limited exploration into its potential for structural load-bearing applications. This is mainly due to the layered structure of 3DPC and the lack of compatibility of conventional reinforcement strategies to be integrated within the 3D concrete printing process. The post-tensioning of 3DPC structures presents an effective solution to improve the load-carrying capacity and cracking behavior of 3DPC. However, understanding the load transfer behavior and failure modes of 3DPC structures under a particular post-tensioning configuration are crucial to determine the permissible post-tensioning load for a structure without premature failure and to understand the distribution of stresses within the concrete structure under post-tensioning loads. The current study aims to investigate the load transfer behavior and failure mode of a 30 mm thick 3DPC formwork designed for one-way ribbed slabs when subjected to end-anchorage post-tensioning. For this purpose, a series of mechanical characterization and load transfer experiments were conducted on ribbed 3DPC formwork. The mechanical characterization investigations involved examining the compressive and flexural strength, as well as the elastic modulus of 3DPC, under various loading orientations relative to the print path. In the load transfer experiments, the end anchorage post-tensioning system was simulated by applying the axial load to the specimen via end plates bonded to the specimen. The variable parameters of the load transfer experiments were the boundary conditions, the eccentricity of the axial load from the neutral axis, and the topology of the ribbed 3DPC formwork. A digital image correlation system was used to study the axial and transverse strain evolution during the load transfer experiments. The experimental results showed that, regardless of the eccentricity of the applied load, the ribbed 3DPC formwork specimens exhibited higher axial load capacity when the load was applied near the bottom flange rather than the top flange. This was because of the reduced effective cross-sectional area for compression when the load was positioned near the top flanges, a consequence of the selected formwork topology, where top flanges were discontinuous to allow for pouring of the cast concrete within the formwork.

Economical design strategies for reinforced concrete one-way slabs: a parametric approach considering material strength and rebar size

Despite the rapid advancements in optimization algorithms for economical reinforced concrete (RC) structures, their application to RC slabs has been significantly limited. The primary constraint is slab depth, governed only by deflection control criteria, which impedes further depth reduction—a key factor in cost optimization. The deflection check relies solely on one design parameter—span length, which is often fixed. This constraint limits the effectiveness of even advanced algorithms, which have consistently failed to deliver substantial cost savings in slab design. To address this issue, this study presents a detailed parametric investigation of three key cost-reducing factors in RC one-way slabs: steel strength, concrete strength, and reinforcing bar sizes, in accordance with the ACI 318–19 code. By bypassing algorithmic constraints, the study formulates optimal design strategies through extensive manual design iterations, providing novel trend-based solutions for cost-effective slab design. The findings indicate that for lower live loads, grade 280 steel offers a 20–30% cost reduction compared to higher-grade steel, despite the latter's strength advantage. However, for higher loads, grade 420 or 500 is recommended. Additionally, optimal bar sizes and concrete strengths are recommended for varying load conditions, offering practical design strategies. This approach provides designers with actionable insights to achieve cost-efficient designs without relying on traditional optimization algorithms.

Behavior of GFRP Reinforced-Concrete Bubbled One-Way Slabs by Encased Composite Steel I-Sections

Behavior of GFRP Reinforced-Concrete Bubbled One-Way Slabs by Encased Composite Steel I-Sections

Evaluation of the Flexural Behavior of One-Way Slabs by the Amount of Carbon Grid Manufactured by Adhesive Bonding

Fiber-reinforced polymers (FRPs), which are resistant to corrosion, are used as reinforcement material for concrete. However, the flexural behavior of concrete members reinforced with FRPs can vary depending on the properties of FRPs. In this study, the flexural behavior of one-way concrete slab specimens reinforced with a new grid-type carbon-fiber-reinforced polymer (CFRP) (carbon grid) manufactured by bonding pultruded CFRP strands to an adhesive was investigated. The experimental results indicated differences in the load–deflection relationships of the specimens depending on the carbon grid reinforcement amount. Specimens in which the carbon grids were over-reinforced or reinforced close to the balanced reinforcement ratio reached the maximum load due to concrete crushing and exhibited ductile failure. The specimen under-reinforced with the carbon grid exhibited brittle failure. Specimens with carbon grid reinforcement close to a balanced reinforcement ratio exhibited maximum loads ranging from 0.43 to 0.61 times the calculated flexural strength, which resulted in becoming 0.86–1.00 lower in the specimens with a wider width of the CFRP strands. This study proposes coefficients to estimate the stiffness of carbon-grid-reinforced concrete flexural members after cracking. Applying these coefficients resulted in stiffness calculations that reasonably simulated the behavior of the specimens reinforced with carbon grids after crack formation.

DESIGN OF PRESTRESS BRIDGE PT LIFERE AGRO KAPUAS SUNGAI BELIDA ESTATE SUKA MAJU VILLAGE MANTANGAI DISTRICT KAPUAS REGENCY CENTRAL KALIMANTAN PROVINCE

PT. Lifere Agro Kapuas (LAK) is a Malaysian foreign company engaged in oil palm plantations. Located in Suka Maju Village, Mantangai District, Kapuas Regency, Central Borneo Province. At that location, there is a river that divides the two production lines of PT LAK. On the river, a temporary bridge made of wood was built, and the condition was quite precarious, but traffic was forced to pass with a tonnage load exceeding the bridge's capacity, and the small dimensions of the bridge caused traffic flow for production facilities to be hampered because they had to pass through the bridge alternately, as a result of technological developments resulted in a concept that is different from the concept of ordinary reinforced concrete. The combination of high compressive strength concrete with steel with high tensile strength result in the concept of Prestressed Concrete, which can handle heavy loads. Loading planning refers to SNI 1725-2016 standard. Floor slab planning uses the Bittner method and is considered a one-way slab so that the largest forces are used between the two methods. In the design of girder beams using reinforced concrete material with an fc' quality of 40 MPa. Tendon type Uncoated seven super wire strands ASTM A-416 grade 270 totaling four tendons each girder. The axial resistance of piles is taken based on the smallest value of the strength of the material, soil drilling data, CPT, or N-SPT. At the same time, the lateral resistance of the Pile is taken from the smallest value of the maximum moment. Based on the results of the analysis, a PCI-Girder H 170 section was chosen with a loss of prestress is 29,8%. The tensile strength of the tendons is 1860 MPa. Floor slab fc' quality 35 MPa with thick 30 cm D29-200 main reinforcement and D16-200 dividing reinforcement. Backrest fc' 25 MPa. The lower structure uses fc' 25 MPa quality concrete. With fabricated pile foundations from PT. Wika Beton type PC Spun Pile B class with 50 cm diameter with 18 piles each abutment.. Keywords: Bridge, prestressed

Flexural Behavior of Reinforced Concrete One-way Slabs with Longitudinal Hollows

This paper presents an experimental investigation of the flexural behavior of reinforced concrete one-way slabs with longitudinal hollows. Hollow ratios (weight reductions) used in this work are 11.43% and 22.86%. Two longitudinal reinforcement ratios (ρ = 0.58 % and 1.03 %) and four steel fibers volumetric ratios (Vf = 0, 0.2, 0.4, and 0.8%), were used. Results show that slabs with longitudinal hollows having weight reduction up to 22.86%, show reductions in strength (ultimate load) up to 32% and toughness (energy absorption) up to 45% and higher deflections compared to corresponding solid slabs. However, these reductions lowered to 27.5% and 24.5%, respectively using 0.8% steel fibers or 6.3% and 25.5%, respectively by increasing longitudinal reinforcement from 0.58% to 1.03%. Furthermore, increasing longitudinal reinforcement from 0.58% to 1.03% along with using 0.4% steel fibers in a hollow slab gives a strength gain of 17.5% with a reduction in toughness of only 9.8% compared to reference solid slab with 0.58% longitudinal reinforcement and 0% steel fibers. Results also showed that hollow slabs offer stiffer load-deflection behavior (lower deflections) and less maximum crack width as longitudinal reinforcement and/or steel fibers.

Identification of crack width behavior of one-way reinforced concrete slab structure at different steel reinforcement area

An evaluation study of crack limit states based on design codes and prior research is presented in this publication. Its main goal is to connect research findings to common design codes. Researchers continue to face a difficult dilemma when it comes to reinforced concrete structure fractures, particularly in one-way slab constructions where there is still significant damage and corrosion in the reinforcement because of cracks. Practitioners will find it easier to construct these structures and solve the slab durability issue if the proper formula is discovered. One can overcome reinforced concrete. A method for estimating the maximum fracture width formula in one-way reinforced concrete slabs with varying steel areas is suggested based on this research. Slabs use a variety of steel areas, including 1000 mm2, 1200 mm2, and 1400 mm2.The test specimens are the same length of 2 meters and have a slab width of 0.6 meters with steel reinforcement. Findings from a literature review of research codes and prediction formulas from earlier studies, namely wmax(prop)=1.5*10-2fsAs-0.4, indicate that the maximum crack width is not significantly influenced by steel area (As). Overall, the findings from the two methods used in this analysis match the suggested formula and the observed experimental testing. This data indicates that the maximum fracture width has been greatly lowered by increasing the steel Area (As) of the reinforced concrete slab, leading to the determination of the experimental formula, As a result, a unique approximation formula has been developed to assess the impact of steel area parameters for pure slabs on the maximum crack width formula for one-way reinforced concrete slabs. This crack width formula is only applicable to one-way slabs in practice.

Effects of structural configuration on perforation/spalling damage and secondary fragment velocity of reinforced concrete slabs subjected to close-in explosion

Reinforced concrete (RC) slabs are vulnerable to localized damage from close-in TNT explosions, suffering perforation and extensive spalling damages that generate high-velocity secondary fragments posing severe risks to nearby facilities and personnel. Current numerical methods such as the Finite Element Method (FEM) face challenges in accurately predicting fragmentation due to mesh distortion caused by large deformations and discontinuities, underscoring the need for enhanced modelling techniques. As a result, although numerous studies have numerically investigated how structural configurations influence RC slab damage under blast loads, the issue of mesh distortion and element erosion in FEM has led to the inability in reliably predicting the associated threats from high-velocity fragments. This study numerically investigates the influences of structural configuration (e.g., concrete strength, reinforcement ratio and layout, dimensions of slabs, and concrete cover depth) on the perforation/spalling area and fragment ejecting velocity of one-way RC slabs subjected to close-in explosions through an ALE-FEM-SPH numerical model, which has been demonstrated effective and reliable in the authors’ previous studies. The results indicate that concrete strength and slab thickness most significantly affect both the damage and fragment characteristics, while the slab's width-to-height ratio, reinforcement ratio, and layout, have less influence, particularly on fragment velocity. Empirical equations derived from extensive numerical data are provided to help engineers and security personnel quickly evaluate the blast effects on RC slabs. The accuracy and robustness of the proposed formulae, which can be straightforwardly used to predict blast fragments of reinforced concrete slabs, have been statistically evaluated and the proposed formulae demonstrate satisfactory precision, with less than 20 % error in estimating damage area, maximum fragment velocity, and total kinetic energy of fragments.

Capacity reinstatement of reinforced concrete one-way ribbed slabs with rib-cutting shear zone openings: Hybrid fiber reinforced polymer/steel technique

This study examined the use of two configurations for capacity restoration of reinforced concrete (RC) one-way ribbed slabs containing openings in shear zones. Four specimens of half-scale comprised three ribs in addition to a top RC slab. The test plan included a control specimen without openings, one with two rib-cutting shear openings, one strengthened using a blend of carbon FRP (CFRP) composites and steel plates, and another retrofitted with a combination of glass FRP (GFRP) composites and steel plates. The two strengthening schemes were found successful at fully restoring the ultimate load of the specimens. The ultimate load of specimen strengthened using the hybrid CFRP/steel system exceeded the control slab without openings by 52%. However, in the other specimen where a mix of steel plates and GFRP sheets was used, the load capacity was only 5% less than the control specimen without openings. While the dissipated energy and stiffness were reinstated and improved for the hybrid CFRP/steel system, they were partially restored for the GFRP/steel system. Additionally, a prediction approach was developed to estimate the maximum load of the slabs. The developed approach considered potential shear and flexural modes of failure, providing close predictions of the ultimate load.

Flexural behavior of corroded one-way slabs strengthened with CFRP in two different techniques

Flexural behavior of corroded one-way slabs strengthened with CFRP in two different techniques

Numerical validation of reinforced concrete one-way slabs under long-term loading using nonlinear finite element analysis

Numerical validation of reinforced concrete one-way slabs under long-term loading using nonlinear finite element analysis

Flexural Improvement of RC Slabs by FRP or Steel Using Different Strengthening Systems and Novel Anchoring Techniques

An experimental study on reinforced concrete one-way slabs strengthened by various methods and materials is introduced in this paper. Innovative anchorage procedures are presented and evaluated to prevent the strengthening elements with FRP system from de-bonding at the initial stages. Externally bonded embedded in concrete cover (EBECC) strengthening technology was proposed to save the fiber strips from being subjected to heat, degradation, and sabotage. Nine RC one-way slabs, including a control slab and eight strengthened slabs, were cast. One RC slab was strengthened using externally bonded embedded in concrete cover (EBECC), whereas the other tested RC slabs were strengthened using either externally bonded (EB) or near-surface mounted (NSM) procedures. The following test variables are used in this study: the proposed anchors, the area of steel, the kind of material utilized in NSM rods (carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), and steel), and the strengthening scheme. The ultimate and initial cracking loads, load–deformation response, cracking patterns, and failure behavior were recorded and discussed. Additionally, a comparison of the stiffness, ductility, and energy absorption of the examined slabs was reported. The strengthened slabs by various techniques showed a boost in flexural strength that varied from 67 to 107% compared to the control slab. In addition, RC slabs strengthened by NSM-CFRP bars showed a maximum flexural capacity when compared with slabs strengthened by GFRP and steel bars. Also, the results supported the superiority of a novel end anchorage. The ABAQUS program was employed to conduct a finite element analysis (FEA) employing 3-D geometries to compare and assess the numerical performance of the identical slabs under similar test settings. The results showed good agreement between the experimental and numerical findings.

Experimental and numerical investigation on deck system of a 102 m simply supported prestressed UHPC box-girder highway bridge

To address two main challenges (excessive mid-span deflections and numerous cracks in the main girder) in long-span prestressed concrete (PC) box-girder bridges, this paper proposes a long-span simply-supported UHPC box-girder bridge. In comparison to conventional PC box-girder bridges with three-dimensional prestress, the proposed UHPC box-girder consists only one-dimensional (longitudinal) prestress, and the thickness of the bottom/top plate and web of the UHPC box-girder are relatively thin and are strengthened with dense diaphragms and stiffening ribs. The 4th Beijiang River Bridge adopts this type of bridge with a span of 102 m, which is the longest span simply supported prestressed UHPC box-girder highway bridge in the world. Considering the fact that the thickness of the top plate of the UHPC box-girder is relatively thin (only 20 cm) and the transverse prestress is removed from the top plate, thus, under the direct action of wheel loads, the risk of bridge deck cracking may correspondingly increase. To investigate the mechanical behavior of the deck system of UHPC box-girder bridges, a 1:2 scaled experimental specimen associated with the field bridge is tested. The mechanical behavior of the new deck system is investigated and discussed. It is found that because the support strength of the stiffening rib is significantly weaker than that of the web, the UHPC deck slab should still be regarded as a two-way slab rather than a one-way slab in the elastic stage. In addition, although the test load location is unfavorable to the UHPC deck slab and the first crack appears on the UHPC deck slab, this deck system finally suffers from bending failure of the transverse rib. Furthermore, finite element analysis is carried out to study the mechanical behavior of this new deck system. Parametric analysis considers some factors including the reinforcement ratio in the transverse rib, the height of the transverse rib, and the space between transverse ribs. The results provide a good reference for design and optimization in the new deck system of UHPC box-girder bridges.

Structural Behavior of Low-Carbon and Functionally Graded Concrete One-Way Slab Strips

Structural Behavior of Low-Carbon and Functionally Graded Concrete One-Way Slab Strips