Two-way Slabs Research Articles

The Impact of Reinforcement Ratio on the Punching Shear of CFRP Grid-Reinforced Concrete Two-Way Slabs

Corrosion of steel reinforcement in concrete slabs undermines structural durability and shortens the lifespan of concrete structures. Carbon Fiber-Reinforced Polymer (CFRP) is a promising material offering benefits such as high strength, corrosion resistance, and light weight. This study aims to investigate the punching shear performance of concrete slabs reinforced with CFRP grids, focusing on the effects of different reinforcement ratios. A series of experiments were conducted on two-way concrete slabs reinforced solely with CFRP grids to assess their punching shear resistance. Experimental results show that the CFRP grid achieves an ultimate tensile strength of 2181 MPa, with the cracking load of CFRP grid-reinforced slabs reaching approximately 20% of the ultimate load, highlighting a strong correlation between the ultimate load and grid reinforcement ratio. The observed punching failure exhibited clear brittle characteristics, characterized by the formation of radial and circumferential cracks on the tensile surface of the slab. The reinforcement ratio significantly influences the failure mode of the slabs; as the reinforcement ratio increases, the ultimate punching loads also increase. Additionally, a mathematical formula is proposed to predict the punching bearing capacity, achieving calculation errors below 20%. These findings contribute valuable insights into using CFRP grids as primary reinforcement, enhancing the design and application of durable concrete slab structures.

Finite Element Analysis of Two-Way Reinforced Concrete Slabs Strengthened with FRP Under Flexural Loading

This paper presents a finite element (FE) model of reinforced concrete two-way slab strengthened using fiber-reinforced polymer (FRP) sheets. This model was validated against experimental data from the literature and it showed acceptable prediction accuracy. Although carbon-FRP (CFRP) is the most commonly used composite in repairing and strengthening reinforced concrete structures, it is important to consider other types of FRP composites such as the eco-friendly basalt-FRP (BFRP) and the newly developed polyethylene terephthalate-FRP (PET-FRP). Therefore, the validated FE model was utilized to perform a parametric study for slabs having different values of concrete compressive strength (ranging from 20 to 80 MPa) and strengthened with other types of FRP. The results show that CFRP provides the highest strength enhancement with a 34.5% increase in the ultimate load, while PET-FRP provides the lowest improvement with an increase of 11.2%, compared with unstrengthened slab. The results also show that the concrete compressive strength (fc’) has moderate influence on the ultimate load. For example, increasing fc’ from 20 MPa to 80 MPa increased the predicted ultimate load for CFRP-strengthened slab from 15% to 62%. The FE model provides a suitable prediction for the ultimate strength and deformability of the strengthened two-way slabs that helps in better understanding of the performance of strengthened slabs and allows engineers to optimize design parameters.

Flexural performance of UHPC two-way slab reinforced with FRP bars

The flexural behaviors of ultra-high-performance concrete (UHPC) two-way square slabs reinforced with fiber-reinforced polymer (FRP) bars were studied experimentally. Flexural tests were conducted on eight specimens, varying in reinforcement type, reinforcement ratio and confinement condition in compressive zone. Test results showed that the bridging effects of steel fibers in UHPC can mitigate the brittle characteristics of slab experiencing punching shear failure. The failure modes of slabs shifted from tensile failure to compressive failure by increasing the tensile strength of bar, leading to an improvement on the flexural capacity and ductility. The ultimate capacity of the slab with a reinforcement ratio of 1.06 % was 15.8 % greater than that of the slab with a reinforcement ratio of 0.67 %. By incorporating a layer of basalt fiber-reinforced polymer (BFRP) grid in the compressive zone to confine UHPC, the bearing capacity and ductility index of the slab increased by 17.8 % and 56.7 %, respectively. Introducing an enhancement coefficient to account for the confinement effect induced by the BFRP grid, a method was developed for predicting the flexural capacity of FRP reinforced UHPC two-way slab subjected to a local load at the mid-span, and its prediction accuracy was well verified.

Theoretical and Experimental Study on the Stress State of Joints in Two-Way Composite Slabs

Theoretical and Experimental Study on the Stress State of Joints in Two-Way Composite Slabs

Structural Behavior of Full-Scale Novel Hybrid Layered Concrete Slabs Reinforced with CFRP and Steel Grids under Impact Load

Reinforced concrete two-way slabs are important elements in the construction field, and their impact response under drop-weight impact is a complex mechanical issue that can cause the collapse of heavy structures. Previous research has documented the analysis of conventional steel-reinforced concrete slabs under impact loads. However, the investigation of layered hybrid concrete composite flat solid slabs reinforced with carbon-fiber-reinforced polymer (CFRP) rebars is an innovative subject. This paper examines the structural behavior of layered novel hybrid concrete composite flat solid slabs with a combination of reactive powder concrete (RPC) in the top layer and normal concrete (NC) in the bottom layer, reinforced with internal CFRP or traditional steel bars in the tension zone, under an impact load test. For this purpose, ten full-scale square flat solid slab samples with a 1550 mm length and a 150 mm depth were fabricated and divided into eight layered hybrid concrete samples with 50% RPC and 50% NC and two samples cast with NC only. The impact tests were carried out using a hardened steel cylindroconical impactor (projectile) with a height of 650 mm and a diameter of 200 mm, a flat nose diameter of 90 mm, and a total mass of 150 kg released from two different heights of 5 and 7 m. The variables considered were the types and ratios of reinforcement, as well as the free-drop weight and height. The experimental results obtained showed that layered RPC flat solid slabs are superior in resisting and sustaining impact forces and also have fewer scattered parts when compared to NC flat solid slabs. Additionally, the flat solid slab samples reinforced with CFRP bar grids were overall more resistant to impact loads, by an average of 19%, compared to flat solid slabs with steel bars and showed lower deflection, by an average of 10%, compared to the other flat solid slabs.

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.

Mechanical performance of eco-friendly self-compacting concrete (SCC) mixtures and two-way slabs partially containing cement kiln dust as cement replacement and internally reinforced with waste plastic mesh

A large quantity of cement kiln dust (CKD) is produced annually during the production of Portland cement. The majority of the produced CKD remains unused except in specific cases related to soil stabilization projects. The current research investigates the production of self-compacting concrete (SCC) mixtures, in which CKD is used as a substitute for cement in different weight proportions, 3 %, 6 %, 9 %, 12 %, and 15 %. The hardened mechanical properties of SCC, such as compressive strength, splitting tensile strength, and flexural strength, as well as the fresh state characteristics (i.e., slump flow diameter, T500, V-funnel, and L-box tests), were recorded and compared with the control mixture which was entirely cast using cement. Results revealed that with an increase in the CKD content beyond 6 %, the slump flow diameter of SCC mixtures significantly decreased. Also, the increase ratios in the V-Funnel flow time for self-compacting concrete mixtures, when replacing cement with CKD ratios of 3 %, 6 %, 9 %, 12 %, and 15 %, were 13.3 %, 30 %, 46 %, 58 %, and 66.7 % respectively, compared with the reference mixture. Additionally, the impact behavior of two-way SCC slabs cast using CKD ratios ranging from 3 to 15 % and internally strengthened using various patterns of recycled plastic mesh was investigated. Strengthening the SCC slabs using two layers of recycled plastic grids proved to be effective in preventing the projectile from penetrating the whole thickness of the SCC slabs, regardless of the CKD content.

Empirical Punching Shear Capacity Equation for Reinforced Concrete Two-way Slabs with Openings

This study proposes a new equation to estimate the punching shear capacity of Two Way Reinforced Concrete Flat Slab Column (TRFSC) connections with openings. The TRFSC connections with openings in the literature were simulated using the finite element modeling technique. Then, the test results were used to calibrate and verify the finite element model. Next, the number of test data was artificially increased using the finite element model to cover a wide range of critical perimeters. Finally, the effects of several parameters such as the size of the openings in the reinforced concrete slabs, their position, and distance concerning the column on which the punching loading is applied on the variation of punching shear load capacity of TRFSC connections with openings were observed, the results showed that the proposed equation generally gave better results than the several current code equations. For the study used in the verification of the finite element model, it was observed that the ratios of the punching capacity values calculated using the experimental results and the regulations varied between 0.79 and 0.92 on average, and the regulations gave results that were not on the safe side for TRFSC connections with openings. However, with the nonlinear correction coefficient proposed in this study, the ratios of the experimental results and analytically calculated capacity values were calculated as 1.10 on average, and the standard deviation and variant values decreased much more.

An experimental and numerical study on two-way RC slabs with openings strengthened by ferrocement technique

This study investigates the impact of creating a central square opening on reinforced concrete slabs and assesses the strengthening process using ferrocement layers. The investigated key parameters were the opening sizes, type, number, and extension length (outside the opening sides) of steel mesh layers used to strengthen the tested slabs. The experimental program included the preparation and testing of twelve two-way reinforced concrete slabs with identical dimensions, thickness, and reinforcement, but were different with respect to opening sizes and strengthening schemes. Four slabs acted as control specimens without strengthening; one was solid; the other three had different opening sizes; and the other eight slabs were strengthened using a ferrocement layer of 2 cm thickness applied on the bottom of the slab around the openings with various reinforcement schemes which included the number, type, and extension length (outside the opening) of steel mesh. All slabs were supported along the four sides with a clear span of 1 m in both directions and tested under four-point loading. The test results demonstrate that creating an opening in the slab decreases the ultimate load by 21.5 %, 31.9 %, and 40.7 % for opening dimensions (15, 25, and 35 cm), respectively. Using the ferrocement strengthening method helps to increase slabs’ flexural load-carrying capacities and reduce crack propagation from opening corners. The study found that strengthening specimens with opening sizes of 15, 25, and 35 cm increased their flexural load-carrying capacities by 26 %, 33 %, and 34 %, respectively. The expanded steel mesh type also resulted in a higher ultimate load by 6–7 % than the welded mesh type. When the length of the strengthening ferrocement layers was doubled, the ultimate load went up by 6–7 %. Increasing steel mesh layer numbers from 1 to 4 increased the ultimate load by 25 % to 40 % compared to the corresponding un-strengthened slab with an opening. The maximum load of a slab with an opening was achieved by applying a 2 cm thickness of ferrocement layer reinforced with expanded metal mesh, with extension lengths equal to the opening's length. The study utilizes commercial software ABAQUS for finite element analysis (FEA) to validate the experimental results, resulting in a great agreement between the analysis and the experimental findings.

Enhancing the punching performance of two-way RC flat slabs using different configurations of embedded aluminum sections: Experimental program and numerical analysis

Punching occurs in flat slabs around the column as a result of increased column loads, inadequate steel reinforcement, and weak concrete strength. The goal of the current research is to improve the punching resistance of two-way reinforced concrete (RC) flat slabs using internal strengthening with aluminum sections. An experimental program consisting of ten RC flat slabs was prepared and tested to show the effects of three different strengthening configurations (horizontal and vertical, diagonal, or hybrid system consisting of horizontal, vertical, and diagonal sections) on the structural characteristics of RC flat slabs. Also, the effect of the thickness of the strengthening aluminum sections (1.0, 1.5, and 2.0 mm) on the ultimate load, load-mid span deflection responses, stiffness, and absorbed energy of RC flat slabs was investigated. According to the results, the three slabs in the group with the vertical and horizontal aluminum sections had the highest improvements in ultimate loads among all tested slabs of 50.9%, 57.1%, and 68.9% for aluminum thicknesses of 1.0, 1.5, and 2.0 mm, respectively, compared to the control slab. Moreover, a three-dimensional (3D) non-linear finite element model (FEM) was constructed using ABAQUS software. The proposed model was validated using the experimental records. Then, the validated model was used to investigate the effects of the interspacing between the aluminum sections on the ultimate load, load-deflection responses, stiffness, and absorbed energy of two-way RC flat slabs.

Investigation of punching shear performance in concrete slabs reinforced with GFRP and synthetic fibers: An experimental study

The punching shear resistance mechanism of reinforced concrete slabs with glass fiber-reinforced polymers (GFRP-RC) is weaker than that of steel-RC slabs. The reduced shear strength and modulus of elasticity of GFRP reinforcement which led to greater tensile strains of the reinforcement and shallower compressive zone reduce the contribution of concrete in compression, aggregate interlocking, and dowel action to the punching shear mechanism. This condition results in reduced capacity and a higher likelihood of catastrophic failure compared to their steel-RC counterparts. To address this weakness of GFRP-RC, this paper aims to examine the punching shear performance of GFRP-RC slabs and explore the potential improvements through the incorporation of synthetic fibers. A total of 11 two-way slabs having a dimension of 1000 × 1000 mm with a thickness of 80 mm were tested under punching shear load and the effect of several types of fiber (polypropylene (PP) and (polyvinyl alcohol (PVA)), fiber content (0, 0.5%), reinforcement ratio, and reinforcement type (steel and GFRP) was investigated. The slabs’ behavior was assessed by considering crack width, deflection performance, the mode of failure, and the overall load-bearing capacity. The findings indicated that the influence of fibers was more noticeable in GFRP-RC slabs compared with steel-RC counterparts. Moreover, the fibers were found to effectively reduce deflections and crack widths. The results particularly showed the superior performance of PVA fibers in improving the capacity of the two-way slabs, whereby the addition of 0.5% PVA fibers led to the punching shear capacity increase of 44–51%. The findings of this study offer a better understanding of the punching shear behavior of slabs reinforced with GFRP reinforcement and synthetic fibers.

An innovative formulation for predicting the punching shear behavior in two-way reinforced concrete slabs

Punching shear failure represents one of the most critical and perilous challenges that slabs may encounter under load-bearing conditions. Numerous studies have delved into the mechanics of punching shear and the methods for assessing the strength of slabs against punching shear failures. However, owing to the inherent complexity of the punching shear phenomenon, a universally applicable relationship has remained elusive. This article introduces a mathematical framework for analyzing the punching shear strength of two-way reinforced concrete slabs. The framework leverages a dataset of 218 laboratory test results compiled from various literature sources. To achieve the objective, the authors preprocessed the database, optimized the computational architecture, established the computational structure, and extracted mathematical relationships from the resulting system, respectively. The punching shear values generated by the computational model presented in this article were also compared with those determined using existing relationships. The framework surpasses existing methods by achieving a demonstrably lower error rate in predicting punching shear strength. This translates into a significant advantage for engineers, enabling them to design two-way reinforced concrete slabs with greater confidence and accuracy. Furthermore, it can be a valuable tool for assessing the viability of strengthening strategies for existing slabs or guiding rehabilitation efforts to ensure structural integrity. By facilitating these applications, the proposed framework holds immense promise for enhancing the safety, reliability, and lifespan of two-way RC slabs.

Behavior of Reinforced Lightweight Concrete Slab with Initial Cracks

The flexural behavior of lightweight concrete two-way slabs repaired or strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) sheets is the subject of this study. The experiment included five reinforced lightweight concrete slab specimens with dimensions of 1000 mm in length, 1000 mm in width, and 120 mm in thickness. Tested one specimen without any strengthening and reinforced another specimen with a single layer of CFRP. The other specimens were repaired with a single layer of CFRP, applying damage ratios of 50%, 60%, or 70% of the ultimate load. Intentionally designed each slab to collapse under bending forces and maintained comparable dimensions. According to the experiment results, changing the degree of damage from 70% to 50% increases the ultimate load capacity by about 17.7%, and the ultimate deflection decreases by about 31.4%. CFRPs have the potential to fix structural damage under static stress testing conditions. However, it is essential to make sure that they stick well to surfaces that do not have suitable geometric properties or have been deformed. CFRP sheets effectively repaired the specimens, increasing the failure stress of the reinforced concrete slabs and preventing the spread of cracks.

Elasto-Plastic Analysis of Two-Way Reinforced Concrete Slabs Strengthened with Carbon Fiber Reinforced Polymer Laminates

This study explores a technique for enhancing the punching strength of reinforced concrete (RC) flat slabs, namely carbon fiber reinforced polymer (CFRP). Four large-scale RC flat slabs were fabricated, to assess the efficacy of this strengthening method. One slab served as a reference and the three other specimens were strengthened with CFRP, as a method of external strengthening. These slabs, featuring identical overall dimensions and flexural steel reinforcement, underwent testing until failure, under the influence of concentrated patch loads. A concrete plastic damage constitutive model (CDP) was developed and employed to examine the strength of two-way RC slabs. Additionally, to enhance the strength of existing RC slabs, carbon fiber reinforced polymer (CFRP) strips are affixed to the tension surface of the sections. The research begins with the calibration of a numerical model, based on data from laboratory tests. The objective of this study is to constrain the plastic behavior of two-way RC slabs reinforced with CFRP, with a focus on establishing an optimal elasto-plastic analysis, aimed at controlling concrete damage plasticity using CFRP, and employing a plastic limit load multiplier. Subsequently, a series of numerical simulations, incorporating different variables, are conducted to investigate shear behavior. The numerical results indicate that an increase in the strengthening ratio has a significant impact on shear strength. Finite element simulations are carried out using Abaqus CAE®/2018.

Low-velocity impact behavior of two-way SFRC slabs strengthened with steel plate

Structural systems and structural elements can often suffer severe damage or even completely collapse under the effect of sudden dynamic impact loading, which is a different type of loading that is not considered during their design. Research on how structures behave under impact loading and how they can be strengthened to perform better against this type of loading has increased to avoid such undesirable severe damage. Within the scope of this study, it is aimed to improve the behavior and increase the performance of two-way steel fiber-reinforced concrete (SFRC) slabs, one of the leading structural elements that can be affected by impact loading, using steel fiber concrete (SFC) and placing steel plates on the surface of the RC slab. Within the scope of the study, the effects of placing FRC as layers in different positions within the slab and placing the steel plate on different surfaces of the slabs were examined. Impact loading was applied using a drop weight test setup designed by the authors, and the acceleration–time, displacement–time, and impact loading–time behaviors of the RC slabs were measured and interpreted. The use of fiber concrete in RC slabs and strengthened with steel plates increased the maximum acceleration values by an average of 3% and 113%, respectively. The use of fiber concrete in RC slabs reduced the maximum displacement and residual displacement values by an average of 2% and 25%, respectively. Placing steel plates on the slabs reduced the maximum displacement and residual displacement values by an average of 270% and 199%, respectively. In addition, the energy absorption capacities of RC slabs were calculated, and how they were affected by experimental variables was examined. Numerical analyses of the RC slabs tested in the study were also conducted using ABAQUS finite element software, and the results obtained were compared with the experimental ones.

Experimental investigation on adaptive concrete slabs equipped with integrated fluidic actuators

One possible approach for saving structural mass and related emissions is to design adaptive load-bearing structures, i.e. actively reducing deformations under changing loads through actuation. This paper describes the application of a methodology based on influence matrices to identify a feasible actuator size for actuator placement in reinforced concrete slabs under multiple load cases. The design is implemented in a physical prototype comprising a concrete slab with a clear span of 2 m x 2 m, being equipped with fluidic actuators that are controlled via a cascade controller. Experimental tests show that the displacement response of the adaptive slab under twice the design load can be kept equal to that of the passive slab under the design load. Thus, proof of concept is provided that considerable material savings can be achieved by employing integrated fluidic actuators in two-way slabs.

Ultimate water level and deformation failures of the artificial dam in the coal mine underground reservoir

Coal mine underground reservoirs provide a new choice for the protection and utilization of water resources. This paper takes the underground reservoir of Wulanmulun Mine as the background, and takes the MB-1# artificial dam in the goaf of 31104–31116 working face of 3–1 coal seam as the research object. The theoretical model of artificial dam is established by elastic–plastic two-way slab theory, and the theoretical mechanical analysis and calculation are carried out. A similitude physical model for the coal mine underground reservoir was built by using the self-developed nested dual-dynamic-pressure similitude simulation testing system. Later, the mechanical response and deformation failure features of the artificial dam under different water pressure values were analyzed and the ultimate water pressure was determined. In addition, FLAC3D was used to determine the stress-seepage field-coupling model for the artificial dam. Using this model, the influence of water pressure on the multi-load coupling effect of the artificial dam and coal pillar dam was characterized. The dam form is optimized and the safety water level evaluation method of the dam body is proposed. The research results are as follows: (1) Based on the theory of elastic–plastic two-way slab, the theoretical analysis model of artificial dam is established, the expression of the ultimate water level function of artificial dam is derived, and the theoretical ultimate water head is determined to be 18.2 m (2) The seepage law of underground reservoir under different water pressures is obtained, and the ultimate water pressure of the model is determined to be 11.43 kPa. (3) It is clarified that the failure modes of the artificial dam are seepage failure and mechanical failure, and it is revealed that the groove area is the weakest position where the dam is most vulnerable to failure. In view of the failure modes of the dam, the I-shaped structure artificial dam is proposed. (4) A safe water level assessment method is proposed for the constructed artificial dam. According to the analysis of on-site monitoring data of MB-1# dam, the actual water level in the reservoir is within the allowable water level range of the artificial dam, and the whole reservoir is in a stable and relatively safe state at present. The reliability of this assessment method has been verified.

Research on the Crushing of Reinforced Concrete Two-Way Slabs by Pulse Power Discharge Technology

The application of pulse power discharge (PPD) technology in the crushing and dismantling of concrete structures has characteristics related to both green and environmental protection, as well as safety and reliability, with broad application prospects in the construction and municipal engineering fields in dense urban areas. Nevertheless, the research into using this technology to break reinforced concrete (RC) slabs is very limited, while the influence of key parameters on the crushing effect of reinforced concrete slabs is not clear. To solve this problem, a finite element model of an RC slab was established by ABAQUS. The effect of a shock wave generated by PPD on the surrounding concrete was simulated by an explosion-load equivalent, and the development process of concrete crack was simulated by a cohesive force model. Based on the results of the model analysis, the effects of reinforcement spacing, as well as diameter and concrete strength on the crushing effect of RC slabs were investigated. The results show that the increase in reinforcement diameter and the decrease in reinforcement spacing have a significant effect on limiting the development of cracks. According to the development of cracks, they can be divided into three types: edge cracks, cracks between central holes, and cracks between edge holes. The influence of reinforcement spacing and diameter on the first two crack widths is the most obvious. The increase in concrete strength also reduces the width of cracks. Based on the analysis results, the calculation expressions of the crushing effect of the PPD technique on RC slabs were established, which provides theoretical support for the popularization and application of this technique.

Anti-Impact Performance Enhancement of Two-Way Spanning Slab through the Implementation of Steel Trussed Bars

Reinforced concrete (RC) slabs represent integral structural components extensively employed in architectural and infrastructural frameworks owing to their inherent robustness and longevity. In contemporary times, there has been a pronounced surge in endeavors aimed at comprehensively elucidating the anti-impact properties inherent in RC slabs. This surge is propelled by a compelling necessity to fortify these structures against the deleterious effects of low-velocity impacts, thereby ensuring their steadfastness and resilience. Consider the thorough investigation into the anti-impact characteristics of RC slabs, which has been rigorously pursued through both experimental and computational methodologies. A plethora of scholarly discourse on this topic is readily available, providing invaluable insights into the structural dynamics governing slabs subjected to low-velocity impacts. However, there is a noticeable gap in research concerning the strengthening of slabs through shear reinforcement, particularly through economical, easily fabricated, and efficient systems such as fabricated trussed bars. The primary objective of this study is to explore the structural behavior of RC slabs fortified with custom-designed trussed bars under the influence of low-velocity impacts. To accomplish this, the Abaqus software platform is explicitly employed for analysis. The slab without any shear reinforcement is experimentally tested and serves as a reference model for numerical verification. Its anti-impact performance is compared with numerical findings. Following validation, simulations are conducted for square slabs strengthened by fabricated trussed bars in orthogonal and diagonal layouts. The results demonstrate that employing fabricated truss bars shear reinforcement with a 3 mm diameter in orthogonal and diagonal layouts enhances the resistance of slabs to damage, resulting in a 28.41% and 47.06% decrease in damage, respectively. The utilization of engineered truss bars as shear reinforcement yields significant improvements in strength, rigidity, and ductility when compared to control samples lacking such reinforcement. This enhancement is particularly evident when the engineered truss bars are arranged in orthogonal and diagonal configurations.

Efficient Structural Analysis: Predicting Punching Shear Strength in Two-Way Concrete Slabs Using Gradient Boosting Machine Learning

This study delves into the application of machine learning (ML), specifically a Gradient Boosting (GB) model, for predicting the punching shear strength (PSS) of two-way reinforced concrete flat slabs. Leveraging a dataset comprising 241 experimental observations from reputable sources, the research investigates the influence of critical factors on PSS, including slab thickness, column section width, effective slab depth, reinforcement ratio, concrete compressive strength, and reinforcement yield strength. Hyperparameter optimization techniques are employed to fine-tune the model's parameters, leading to enhanced predictive performance. Monte Carlo simulations are utilized to validate the model's reliability and generalizability. The results demonstrate that the GB model achieves high precision and reliability, reducing the need for resource-intensive experimentation in predicting PSS for two-way slabs. Furthermore, the study compares the performance of the developed model with that of conventional design codes, highlighting the model's superior accuracy. This research contributes to the broader application of ML in structural engineering, offering an efficient and accurate approach to analyzing and designing structural elements.