Tension Face Research Articles

Impact response of textile-reinforced 3D printed concrete panels

This study assessed the impact response of 3D-printed textile-reinforced concrete for structural applications of 3D concrete printed structures, where impact is a significant load case. To study the impact response, two layers of AR-glass and two layers of carbon textile-reinforced 3D-printed high-strength concrete panels were investigated experimentally under low-velocity impacts from drop weights, respectively. The effect of textile reinforcement on the impact behaviour was compared with unreinforced printed specimens. The specimens were subjected to increasing levels of impact load until the failure was observed. The effect of textile reinforcement on the impact resistance, cumulative energy absorption capacity and failure pattern of printed specimens were investigated and compared with their mould-cast counterparts. To understand the effect of textile reinforcement on the printed and mould-cast panel specimens, a quasi-static flexural test was performed to evaluate the load vs deformation behaviour. The test results from the quasi-static flexural test showed that the incorporation of textile reinforcement improved the first crack strength by about 40 % and enhanced post-peak behaviour for both printed and mould-cast specimens. Further, providing carbon textile reinforcement significantly improved the impact resistance by 75 % when compared to AR glass textile-reinforced specimens due to the higher stiffness and better strain-hardening behaviour. Moreover, the effect of textile reinforcement on enhancing the energy absorption capacity of 3D-printed specimens was more evident at higher impact velocities. The cumulative energy absorption capacity of carbon textile-reinforced specimens was observed to be 60 % higher compared to AR glass textile-reinforced specimens. During high-velocity impacts, the textile reinforcement was observed to improve damage distribution by enhancing the bridging between the interlayers. The damage condition at failure showed that AR-glass textile-reinforced printed and mould-cast specimens showed severe punching failure on the compression face and widened cracks and spalling on the tension face. However, carbon textile reinforcement enhanced the impact resistance, thus showing multiple cracks and reduced spalling on the tension face even after multiple impacts. Overall, the impact performance of 3D-printed textile-reinforced concrete panels showed high-level impact resistance.

Reinforcement concrete beams with external steel elements

The reinforcement of structural elements is widely practiced worldwide. It can be applied due to deterioration of the concrete, either due to age, change of use, extensions, or updating of the design code. However, it is sometimes used with inappropriate materials or without technical supervision or structural design. The main purpose of this paper is to investigate the method of strengthening based on the external addition of steel elements and to determine its influence on the flexural load-carrying capacity of reinforced concrete (RC) beams. For the same area of external steel, two types of beams are defined: the first one with cold-formed angle sections at the bottom corners, and the second one with a steel plate in the center of the tension face of the beam. The behavior of a total of 12 beams under monotonic and cyclic loading is experimentally studied. The connection was made with post-installed expanding bolts, without adhesives. The configuration that presents adequate results in terms of strength, flexibility, and energy, this obtained with the addition of a steel elements. On the other hand, the use of angled sections, contrary to expectations, reduces the load-carrying capacity and ductility of the section.

P-M INTERACTION DIAGRAMS FOR REINFORCED CONCRETE WALLS RETROFITTED WITH EXTERNALLY BONDED CARBON-FIBER REINFORCED POLYMER

This research develops analytical axial load-bending moment (P-M) interaction diagrams for reinforced concrete (RC) walls retrofitted with carbon fiber reinforced polymer (CFRP). A 12-inch thick, 1-foot strip of RC wall section is considered with varying reinforcement ratios, varying axial compressive loading, and varying number of CFRP layers. The CFRP material is treated as externally bonded onto the tension face of the RC wall to investigate its impact on the flexural capacity of the section. Each P-M interaction diagram was generated considering a discretized compression zone and by satisfying principles of static equilibrium and strain compatibility. An elastic-plastic steel stress-strain relationship is used for Grade 60 reinforcement; a uniaxial nonlinear compressive stress-strain relationship is used for concrete; and a linear stress-strain relationship is used for CFRP in tension. The failure modes considered are steel yielding, concrete crushing, and CFRP debonding. The computed P-M interaction diagrams are normalized for their general use in the retrofit of existing RC walls using CFRP. Results show that as the axial compressive force on the RC wall increases, the less effective CFRP is. CFRP is more effective in sections with beam-like behavior, where the reinforcement ratio tends to be the smallest.

Dynamic Response Analysis of Slab Subjected to Central Contact Blast: Exploring Effects of Blast Placement on Compression and Tension Faces

Dynamic Response Analysis of Slab Subjected to Central Contact Blast: Exploring Effects of Blast Placement on Compression and Tension Faces

Study of Cyclic behaviour of Corroded HPC beams strengthened with GFRP laminates by Nonlinear finite element modelling and experimental investigations

Corrosion is a very big threat to the civil Engineering Structures especially on the coastal areas. Apart from the corrosion, the tidal forces on the structures act as the cyclic loading which in turn damage the structures by way of cyclic loading. There are two types of cyclic loading, which are constant amplitude and varying amplitude. In this experiment, cyclic loading was taken with Constant amplitude. Strengthening the corroded beams on tension face ie below the beams with GFRP laminates improve the cyclic life of the beams. In this paper, the non linear finite element analysis (ANSYS) for the corroded high performance concrete beams under cyclic loading to predict the cyclic life of the beams. The results were compared with the experimental results with regard to cyclic life and Maximum deflection. It is found that it is reasonably agreeable. This indicates that the proposed FEMs can capture the cyclic behavior of the corroded HPC beams strengthened with GFRC laminates of 2 different thicknesses of high accuracy.

Numerical Studies on Flexural Behaviour of Graded Multi-Layer Puf Cored Sandwich Panels

The present numerical investigation was mainly concerned with the evaluation of flexural properties of graded multi-layered polyurethane foam cored (MLCC) sandwich panels using a novel approach through the medium of general purpose program i.e. FEM/ANSYS. Aiming to the goal, three-point bending analysis was performed on sandwich beam models assumed to be made up of composite face sheets (GFRP) and graded multi-layer polyurethane foam cores of different layer densities. Finite element models of sandwich beams were obtained successfully using nonlinear shell 91 elements for face sheets (orthotropic material) and 8-noded shell 98 elements for core (isotropic material).Various multi-layer core configurations in a stack of three layered core were studied with great care. Prior to actual task, the proposed evaluation technique was verified using bench marks. Series of multi-layered cored beam models of different core configurations and span length were analysed in order to study the influence of different graded (density) layer configuration on flexural properties. The present studies reveals that use of MLCC panels for sandwich construction can provide improved flexural properties and hence these panels could be the better choice for structures under non uniform bending and shear loads due to their higher shear stiffness values compared to soft PUF cored panels. Furthermore the MLCC-2 panels in which layers arranged in order of higher to lower density between compression face and tension face stand better among all the possible core configurations.

Behaviour of UHPFRC-retrofitted RC beams with varying strengthening configurations under single and repeated blast loading

The objective of this study was to characterize the effects of various UHPFRC strengthening configurations on the blast performance of reinforced concrete (RC) beams. The methodology involved blast tests on eight as-built and UHPFRC-retrofitted RC beams using a pneumatically-driven shock-tube. The 150 mm × 200 mm × 2440 mm beams were first cast with 40 MPa concrete and were retrofitted by replacing the 20 mm cover with UHPFRC. The studied parameters included the influence of UHPFRC applied on the tension face, or in the form of U, Full or localized jackets, under single or repeated blast loads. The first set included one as-built beam and three specimens with tension-sided (T), U-jacket (UJ) or full jacket (FJ) retrofits, and were tested under repeated and gradually increasing blast pressures (Pr = 16, 38 and 50 kPa, for Blasts 1, 2 and 3). The second set included one as-built beam and two specimens with full-jacket retrofits applied over the full span (FJ) or in the middle hinge region (FJ-Hinge). The final beam had a hybrid of the T-sided and FJ-Hinge schemes. These beams were tested under single Blast 3 loads, and then tested under static bending to assess their residual capacity. In the first set, all retrofits resulted in reduced displacements (ranging from 30% to 60%) when compared to the as-built beam; however, the repeated blasts ultimately led to crack localization and rupture of the tension steel bars. In the second set, both the full-span and localized hinge schemes led to reductions in damage and displacements (ranging from 20% to 40%), without bar fracture, along with significant residual capacity. Finite element (FE) modelling using LS-DYNA was used to predict the blast behavior of the beams. After validation, the models were used to study the effects of the longitudinal steel ratio and blast load scenario on the behaviour and failure mode of the beams. Increasing the steel ratio was found to be effective in preventing bar rupture, while this failure mode was more likely under repeated blast loading.

New models for reinforced concrete precast hybrid deep beams under static loads with curved hybridization

In this study, two innovative proposals of hybrid precast deep beams are suggested making of the arching action, tied arch and Strut-and-Tie (STM) models. The first one which is called as the “curved hybrid” that consisted of two type of concrete with curved layers while the second, which is termed as “arched hybrid”, consisted of using three layers of concrete that constitute a high strength concrete arch within the beam. The proposed models incorporated reducing weight with keeping capacity without significant drop and, may result in cost minimization. Eleven deep beam specimens with dimensions of (180 × 450 × 1700) mm have been tested experimentally up to failure under two systems of static loading. Several variables have been considered including; loading configuration, type of hybridization, density of concrete at the tension face and quantity of shear reinforcement. Results revealed that using the conventional hybrid model tested under two-point loading system improved the ultimate load by 27%. For the first proposal of arched hybridization, the improvement was 39%. For the second proposal of arched hybridization, the improvement was 45%. When testing deep beams under one-point load, the improvement was reduced by a range of (1–5) % relative to the control beam. Moreover, it is found that using lightweight concrete under the curved interface line instead of normal weight concrete resulted in reducing capacity by 1% for both systems of loading. Regarding ductility and toughness, enhancements ranged in (33–108) % and (140–375) % respectively under two-point loading. When testing under one-point load, the respective values are (7–48) % and (28–180) %.

Potentiality of far surface-mounted reinforcement for flexural strengthening of reinforced concrete beam

ABSTRACT This paper explores the potentiality of a proposed strengthening technique named as Far Surface Mounted (FSM) reinforcement for flexural strengthening of RC beam. In this technique the reinforcement is mounted in the tension face of the beam away from the existing beam surface and cast new concrete to increase the flexural capacity of the beam. Results of total 14 tested beams are analysed and presented here in this paper. To evaluate the performance of the new strengthening technique, the load-deflection behaviours of the beams strengthened with new technique are compared with the results of control beam and another beam strengthened with Near Surface Mounted (NSM) reinforcement method. It was found that the beam strengthened with new technique has higher flexural capacity than the control beam and beam strengthened with NSM technique. The influence of shear key spacing and inter-surface locking behaviour are also explored. In most of the cases, it found that the final failure modes are the shear and deboning of the added layer of concrete for the beams strengthened with new technique.

Study on the flexural and ductility behaviour of plate reinforced concrete beam-A review

A comprehensive literature review on the basis of the flexural and ductility behaviour of the plate reinforced concrete beams are presented in this paper. The objective of this paper is to provide a review of the development and current progress in the flexural and ductile behaviour of plate-reinforced concrete beams. The composite beams are composed of plain concrete beams strengthened by steel plates, externally bonded to their tension faces. The effects of four parameters; namely, plate thickness, beam size, concrete strength, and adhesive type on the moment capacity, deflection, and failure mode of composite beams are studied. This paper also highlights the use of plate thickness and beam size, which has a significant impact on the flexural strength, stiffness, and failure mode of composite beams. Furthermore, this literature study also identifies areas, where further research is needed, such as, the effect of the adhesive type and concrete grade on the properties of composite beams.

Flexural Performance of Composite RC Beams Having an ECC Layer at the Tension Face

This paper presents an experimental study on the flexural behavior of composite Reinforced Concrete (RC) beams having a monolithic Engineered Cementitious Composites (ECC) layer at the tension face. Due to the brittle nature of normal concrete, clear cover on the tension side of beam cracks results in spalling and corrosion of reinforcement. The proposed technique overcomes the inherent brittle behavior of normal concrete with the incorporation of ECC on the tension face. This also helps in reducing bond-splitting, cover-spalling, and buckling of reinforcement in RC flexural members. For testing purposes, six full-scale beam specimens (225 mm x 300 mm x 2400 mm) with the same reinforcement were cast and tested. Out of six, two specimens were made of conventional concrete, whereas the remaining four (two each) had an ECC layer of 75mm and 100mm thick at the tension face respectively. Each specimen was installed with three strain gauges (one each at the midspan top & bottom surface of concrete and one midspan rebar on the tension face) and one LVDT at midspan. The samples were then subjected to simple monotonic loading under a third-point bending test as per ASTM C78. The load-displacement, stress-strain and moment-curvature curves were obtained for all the tested specimens. It was found that ECC-strengthened beam samples displayed an increased flexural performance at first crack, yield, and ultimate load-carrying capacity as compared to conventional RC specimens. Whereas a better crack arrest with even distribution of cracks and improvement in ductility was observed for the ECC-strengthened composite beams.

Behaviour of carbon fiber reinforced polymer strengthened and retrofitted RC beams

This paper deals with an experimental investigation on self-compacting concrete (SCC) reinforced concrete beams of size 150x150x700mm with externally bonded carbon fiber reinforced polymer (CFRP) composites for flexural and shear strengthening. In general, strengthening techniques aims to improve load carrying capacity. Mix proportion for M30 grade concrete was arrived by Nan Su method. The strengthening techniques included are of four types such as Beam strengthened at tension face (BST), Beam strengthened at tension face extending to half depth on two sides of the beam (BSHU), Beam strengthened with four numbers of U-strips (BSUS) and Beam strengthened with two number of U-strips with CFRP inserted in hole (BSUR). Further the failed control beams were retrofitted by similar application as adopted for strengthening and were tested for load–deflection behaviour. The results indicate that among the four configurations, the beam strengthened at tension face (BST) has better flexural response compared with beam strengthened at tension face and extended to half depth at two sides of beams. Beam strengthened with 50 mm wide U-strips with CFRP inserted in a hole exhibited significant increase in toughness. Correlation equations have been developed by using regression analysis and coefficient of correlation obtained are in the range of 0.98 to 0.99 for various applications.

Ultra high performance concrete and C-FRP tension Re-bars: A unique combinations of materials for slabs subjected to low-velocity drop impact loading

In this research work, different combinations of normal strength concrete (NSC), ultra-high-performance concrete (UHPC), and steel fiber-reinforced UHPC (SFR-UHPC) concrete with re-bars of conventional steel and of carbon fiber-reinforced polymer (C-FRP) are used in a two-way square slab of size 1000mm x 1000mm x 75mm subjected to 2500 mm free-fall impact loading. Experimental arrangement consisting of 105 kg dropping weight with the circular flat impacting face of 40 mm diameter used for carrying out impact test is modeled using a high-fidelity physics-based finite element computer code, ABAQUS/Explicit-v.6.15. After validating the experimental results of the NSC slab with steel bars, analyses are extended by replacing NSC and steel bars with UHPC/SFR-UHPC and C-FRP bars, respectively, under the same dropping weight. Only the remote face (tension face) of the slabs is provided with the re-bars. Widely employed and available with the ABAQUS, the Concrete Damage Plasticity model with strain-rate effects has been entrusted for simulating the concrete plastic response. Re-bars of steel are idealized with the Johnson-Cook plasticity damage model. C-FRP re-bars are defined with the classical plasticity model following the elastic-plastic constitutive laws. The impact responses of the slabs consisting of NSC/UHPC/SFR-UHPC concrete with re-bars of steel, and C-FRP combinations considered are discussed and compared. Slabs made of UHPC/SFR-UHPC concrete with the C-FRP re-bars are found to offer a promising combination of materials to withstand low-velocity impact load with little damage and extraordinary impact performance.

Structural performance of reinforced concrete beams with 3D printed cement-based sensor embedded and self-sensing cementitious composites

Cementitious composites containing conductive functional fillers can achieve self-sensing and continuous monitoring of the damages and cracks through piezoresistive characteristics defined as the electrical resistivity change under external deformation. Previous studies developed two types of self-sensing cementitious composites expressing superior piezoresistive characteristics, as well as good linearity, repeatability, and sensitivity. This research further investigates the flexural damage sensing capability of the developed self-sensing cementitious composites by applying them to reinforced concrete beams. The 3D printed self-sensing cementitious composites containing carbon fibre (CF) at 0.7 wt% and activated carbon powder (ACP) at 0.25 wt% were tested as the embedded sensors in this study. Mould cast self-sensing cementitious composites developed by 100 wt% of magnetite aggregate (MA), 0.3 wt% of CF, and 0.05 wt% of carbon nanotube (CNT) were examined in bulk form. The corresponding fractional change in resistivity (FCR) was attained on the tension face of the reinforced concrete beams when subjected to flexural loading. Experimental findings suggest that the embedded 3D printed cement-based sensors in beam elements can contribute to the load-carrying capacity of the reinforced concrete beam, achieving an average load of yielding at 88.65 kN and a maximum loading capacity of 111.09 kN, which is 10% and 12% higher compared with the controlled reinforced concrete beam, respectively. In terms of sensing performance, both 3D printed self-sensing cementitious composites in sensor form and mould cast self-sensing cementitious composites in bulk form could reflect stress and strain changes and detect crack formation in reinforced concrete beams, which demonstrate gage factors at 318 and 527, respectively. However, 3D printed cementitious sensors are more effective when reinforced concrete beams are severely damaged. In terms of self-sensing cementitious composites in bulk form, the randomly distributed CF and CNT could provide a more pronounced crack and damage sensing capability, with fluctuations that can be observed at both low and high levels of damage.

Experimental studies of reinforced concrete beams with external reinforcement of the tensioned face using composite fabrics

The object of the study is reinforced concrete beams that are reinforced with technical polyamide (kapron) fabric produced by Branch “Khimvolokno Plant” JSC “Grodno Azot”, and fiberglass, manufactured by JSC “Polotsk-Steklovolokno”. The relevance of the stems from the need to obtain and study experimental data of the load-bearing capacity, fracture pattern, crack resistance and cracking of reinforced concrete beams reinforced with composite fabrics, since the topic of restoring the load-bearing capacity of reinforced concrete structures or their strengthening is currently very relevant. Reinforcement of bent reinforced concrete structures with composite fabrics allows using fabrics along the outer edges of the structure, as they are resistant to the external environment and are not subject to corrosion, and represent external composite reinforcement, which, together with metal reinforcement, perceive tensile forces. The most common system for the restoration of reinforced concrete structures is currently the system of external reinforcement of carbon tapes, but the use of this material is limited by high cost. The aim of the study is to experimentally confirm the possibility of effective use of technical polyamide (kapron) fabric, produced by Branch “Khimvolokno Plant” JSC “Grodno Azot”, and glass fabric, produced by JSC “Polotsk-Steklovolokno”, to strengthen the stretched face of reinforced concrete bent structures. Two reinforcement options are presented: gluing horizontal tapes along the entire length on the lower stretched face and the device of a U-shaped clip of fabrics in the stretched zone. Experimental studies have shown that the external reinforcement of the stretched zone with technical polyamide (kapron) fabric produced by Branch “Khimvolokno Plant” JSC “Grodno Azot”, and fiberglass manufactured by JSC “Polotsk-Steklovolokno” change the nature of destruction, increase load-bearing capacity of reinforced concrete beams by 16–38 % in depending on the material and method of reinforcement, affect the crack resistance and crack formation. The results of experimental studies made it possible to solve an important applied problem of the effective use of these composite materials as external reinforcement of the tension face of bending reinforced concrete beams.

Experimental Investigation of Hybrid Beams Utilizing Ultra-High Performance Concrete (UHPC) as Tension Reinforcement.

Ultra-high performance concrete (UHPC) is a new generation concrete with extremely high tensile and compressive strength, high durability, and ductility. UHPC offers tremendous opportunities for use in new thin and slender structural concrete elements and repair of existing concrete structures and has an excellent potential to replace conventional steel reinforcement in normal concrete (NC) members. This paper investigated the potential application of a hybrid NC-UHPC beam using a thin UHPC layer on the tension face to cater to tensile stresses, eliminating the need for passive steel reinforcement. Four-point flexural load tests were performed on 24 composite beams with a thin UHPC layer overlaid with NC. The parameters considered include the thickness of the UHPC layer, depth, and span of the beam. A linear behavior categorizes the flexural behavior of the hybrid NC-UHPC beam up to the ultimate load, after which the hybrid beam shows a non-brittle failure, and softening ensues associated with cracking, increased deflection, and loss of load resisting capacity. The unfinished top surface of the UHPC layer and the overlying NC developed a full composite action without any slip. It was found that a two-day self-curing of the UHPC layer was found to be essential for the development of a strong bond between the layers. The random dispersion and orientation of steel fibers in the UHPC can lead to a decreased tensile response for larger hybrid NC-UHPC beams. The experimental results validate the potential of hybrid NC-UHPC beams as an attractive, structurally feasible, and alternative sound form of construction in terms of their high flexural strength and corrosion-free service life. The proposed unreinforced hybrid system could be used in the construction of precast beams and slabs for residential as well as industrial buildings. Further research, including full-scale load testing of the hybrid beam, is needed prior to practical applications.

The behaviour of anchored extended blind bolts in concrete‐filled tubes

AbstractExtended Hollo‐Bolts (EHBs) are blind bolts that have an extended bolt shank ending in an anchor nut. When used with concrete‐filled tubes, the extension and the anchor in the concrete serve to enhance significantly the performance of both connection components: bolts in tension and tube face in bending. The enhancements are a result of confining the concrete, preventing local buckling of the steel tube and allowing the blind bolt to achieve a tensile strength equal to that of standard bolt+nut fasteners. Overall, the use of the EHB results in a moment‐resisting bolted connection to hollow sections which can achieve rigid behaviour under certain configurations. This paper summarizes research work done to date on such connections at the University of Nottingham. This includes experimental, numerical and analytical modelling. The aim of the work is to provide a fundamental understanding of the behaviour of anchored blind bolt connections to concrete‐filled columns, leading to the specification of appropriate design rules that allow the use of such bolted moment‐resisting connections in practice. The work has proposed analytical models for: connection stiffness, column face‐bending strength considering both single and group behaviour of bolt rows, anchored bolts in tension and anchored bolts under combined tension and shear.

Flexural behavior RC beams strengthened and repaired with SRP composite

This paper presents the results of an experimental investigation conducted to study the flexural response of reinforced concrete (RC) beams strengthened and repaired using externally bonded steel reinforced polymer (SRP) composite. SRP composite strips were bonded to the tension face of four RC beams, which were tested in four-point bending. Parameters varied were the presence/absence of U-wrap anchorages and loading rate. The difference in the loading rates employed did not appear to have a significant effect on the yield load, maximum load, or failure mode. The strengthening system without anchorage increased the yield load by 16% relative to the control beam, whereas the strengthening system with U-wrap anchorages increased the yield load by 26–34% relative to the control beam. Values of the maximum strain in the composite at the maximum load of the strengthened beams with U-wrap anchorages ranged from 0.9% to 1.2% and were more than twice as large as that of the strengthened beam without anchorage. The peak fiber stress obtained from single-lap direct-shear tests of SRP-concrete joints was similar to the maximum fiber tensile stress obtained by sectional analysis for the strengthened beam without anchorage.

Shear enhancement in reinforced concrete cantilevers with multiple point loads

The shear resistance of reinforced concrete beams is enhanced by arching action when loads are applied to their top face within around twice the beam effective depth (d) of the supports. Previous experimental investigations into shear enhancement have almost exclusively considered simply supported beams with a single point load applied within 2d of supports. Such academic tests are unrepresentative of practice, where loading and support conditions are usually more complex. For example, balanced cantilever cross-head girders of bridges and continuous beams can have multiple point loads applied to the flexural tension face within 2d of supports. Such cases have not previously been investigated experimentally. An experimental programme was thus carried out to investigate shear enhancement in balanced cantilever beams subjected to pairs of concentrated loads within the failing shear span. The shear resistance of the cantilever beams was found to be slightly less than matching simply supported beams, with the difference greatest for beams without shear reinforcement. A strut and tie model was developed for cantilever beams with pairs of concentrated loads applied to the tension face within 2d of the supports. Measured beam strengths were also compared with the predictions of various codes and non-linear finite-element analysis.

CONCRETE SLAB REINFORCED WITH GFRP AND EXTERNALY STRENGTH WITH CARBON SHEET UNDER IMPACT LOAD

When FRP bars used in concrete structures that exposed to harsh environments, their service life extended and the cost of their life cycle reduced. Recently, methods of externally bonding Carbon Fiber Reinforced Polymer (CFRP) sheets to RC slabs proposed to improve the dynamic behavior of RC slabs under impact load. In this study, the effect of the number of CFRP sheet layers (one or two) and the arrangement of CFRP sheets (covering the whole or parts of the surface) on the dynamic behavior of slabs reinforced with GFRP bar investigated. Nine specimens of (1550×1550×150) mm reinforced by GFRP bars were tested. A single control specimen was unstrings and eight specimens were strength with CFRP sheet on the tension face. A rigid steel projectile used to apply two dropping-weights of 150 kg as an impact load. The height of the drop was 5 meters. To determine punching shear capacity and critical velocity of perforation, different codes used and compared with the experimental results. The results of the experiments revealed that slab shear properties have a significant impact on their general behavior. Strength slab with carbon sheet enhances the behavior of RC slabs under impact loads and increases shear punching capacity.