Punching Failure Research Articles

Analysis of the progressive collapse of a parking garage concrete structure due to punching shear

This work aims to clarify the causes leading to the structural collapse of the garage of a residential development located in Santander, Spain, in 2020. Visual inspections of the collapsed area were carried out to establish the first hypotheses about the collapse. Subsequently, the materials, geometry and acting loads were studied to compare them with the original project. The main conclusion was that the slab was subjected, in the area where the collapse began, to gravity loads of 34 kN/m2 when it was designed to support 15 kN/m2. Then, structural verifications were performed in accordance with EHE-08 and Eurocode 2, in force during project design, to identify the failure mechanism(s) that caused the progressive collapse of the structure. Unacceptable safety factors were observed for punching shear, which was the main failure mechanism. Punching was aggravated by cavities detected in the concrete, which caused both a decrease in the slab strength (lower effective depth of the slab) and an increase in the stresses in the compression struts of about 20 % to 30 %, which considerably reduced the punching safety levels. This calculation was carried out by means of a finite element analysis with SAP2000. The assessment of this type of defect, very common during the execution phase, is not well developed either from a theoretical or regulatory point of view. This paper proposes, as a corrective measure, the inclusion both in the European and National Standards of a mandatory inspection procedure based on Ground Penetration Radar or ultrasounds, during the execution phase, to detect and correct this type of defect, not detectable by visual inspection. Finally, a bending and cracking analysis were also conducted, giving values of the corresponding safety factors of less than unity. Therefore, they also contributed to both the progressive loss of strength of the slabs and the final punching failure. These last two causes are also crucial to understand why the collapse occurred 15 years after its commissioning.

Effect mechanism of low-velocity impact loading rate on the failure modes transition of steel-UHPC-steel composite plates

This study delved into the transition mechanism of loading rate on the failure mode transition in steel-ultra-high performance concrete-steel (SUHPCS) composite plates under concentrated low-velocity impact loads. A series of drop-weight tests elucidated that, as impact velocity escalated, the composite plate shifts from local punching failure, characterized by circumferential cracks, to overall flexural failure, marked by radial cracks resembling yield lines. Given the constraints in capturing strain data in drop-weight test, a 3D nonlinear structural analysis using Abaqus software was conducted. This numerical simulation method was validated by drop-weight test results in terms of crack patterns and impact force time histories. Moreover, structural dynamic punching and flexural loads at a specific loading rate were obtained with the assistance of the dynamic increase factor (DIF). Failure mode could be judged through comparison between the two critical loads. The discrepancy in strain sensitivity exhibited by steel plates and UHPC accounted for the transition in failure modes of the SUHPCS composite plates. DIFs for UHPC compressive strength and steel plate strength were lower than DIF for UHPC tensile strength, as these factors were around 1.5, 1.7 and 2.6, respectively. Parameter analysis showed that the critical transition impact velocity for a composite plate with a core thickness of 80 mm was 11 m/s, surpassing the 13 m/s threshold for a composite plate with a 100 mm-thick core. Moreover, changes in DIFs of UHPC and steel strengths were less than 2 % with various impact masses and the composite plate maintained the same failure mode.

Research on cyclic behavior of precast bridge piers with ECC-socket connections

Precast bridge piers with socket connections (SCPs) have been widely studied and certainly applied in recent years. To reduce the punching failure of socket connections, decrease their construction difficulty, and improve their application in complex environment areas, the embedment depth of SCPs needs to be decreased and the cyclic behavior of SCPs needs to be improved. In this study, engineered cementitious composite (ECC) was firstly introduced to the SCPs, a novel precast bridge piers with ECC-socket connections (SCEs) were proposed. Subsequently, 3D finite element models (FEMs) were established and validated against experimental results. Then, a detailed parametric study was conducted to investigate the cyclic behaviors of SCEs, including the embedment depth, ECC height, axial compression ratio, reinforcement ratio, and concrete compressive strength. Finally, a simplified calculation model was proposed to evaluate the bearing capacity and failure mode of SCEs. The results show that the shear damage of the embedded section is more severe for traditional shallow socket connections. Compared to traditional SCPs, the cyclic behavior of SCEs is better and influenced by ECC height and embedment depth, as well as axial compression ratio, reinforcement ratio, and concrete compressive strength. The simplified calculation model is suitable to evaluate the bearing capacity and failure mode of SCEs.

Blind competition on the numerical simulation of slabs reinforced with conventional flexural reinforcement and fibers subjected to punching loading configuration

AbstractThis paper describes the 3rd Blind Simulation Competition (BSC) organized by the fib WP 2.4.1 which aims to assess the predictive performance of models based on the finite element method (FEM) for analysis and design of fiber reinforced concrete (FRC) structures submitted to loading and support conditions that promote punching failure mode. Fiber reinforcement is used in an attempt to eliminate conventional punching reinforcement and provide technical and economic advantages. The two tested real‐size prototypes represent a column‐slab interior region of an elevated steel‐fiber reinforced concrete (E‐SFRC) slab where anti‐progressive collapse reinforcement is disposed in the alignment of columns/piles. Despite a punching failure surface being formed in both experimentally tested prototypes at the rupture stage, fiber reinforcement was able to mobilize the yield capacity of the conventional flexural reinforcement, providing high deformation capacity, and ductility to the prototypes. The average post‐peak load‐carrying capacity of the tested prototypes at a deflection seven times higher than the deflection at yield initiation of the conventional reinforcement was still 90% of the average peak load. Regarding the BSC, a total of 26 proposals were received and involved 94 participants from 29 institutions and 17 countries, with 53.9% using smeared crack models (SCMs), 30.8% a concrete damage plasticity (CDP) model, 3.8% discrete crack models (DCMs) and 11.5% considered as “other models.” From these simulations it was verified, in average terms, that SCM assured the best predictive performance apart from the average strain in the SFRC and the maximum crack width which were better predicted by DCM. More accurate predictions were obtained by using in‐house software than by adopting commercial software.

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.

Research on failure characteristics and mechanism of ZK61m magnesium alloy plate under the impact of ogival projectile

To study the influence of the thickness effect on the impact performance of ZK61m magnesium alloy plate, the influence of ogival projectile on the impact performance of magnesium alloy plate of different thicknesses is analyzed through experiments and numerical simulations, the ballistic limits and failure modes of different thicknesses of the punch target plate are obtained. The velocity of the plug is analyzed by introducing the extruded chisel block velocity model. The experimental results show that the ballistic limit value of the target plate in a specific thickness interval (7 ∼ 11 mm) increases slowly with the increase of its thickness, and the failure mode is dominated by the shear punching failure and accompanied by the tensile failure. The plugs formed in the experimental process are consistent with the extruded chisel block velocity model. Numerical simulation results show that the MJC fracture criterion predictions deviate from the experimental results due to the overestimation of the material ductility, while the Lode parameter dependent MMC fracture criterion, which can better predict the ballistic behavior and failure modes of the target plate.

Effect of the pile cap length and the soil relative density on the pile cap – pile – dense soil interaction: Experimental investigation

In the present study, the RC pile cap-pile-soil interaction was experimentally investigated by testing twelve half-scale RC pile caps. Two main parameters were considered within the experimental program; the first factor was the relative density of the supporting sandy soil. Four models were tested without being rested on soil, while the other eight models were rested on sandy soil with a relative density of 80% or 90%. The second studied factor was the ratio between the spacing between the RC piles and the width of the pile (S/D), which varied within the range of 2.25, 2.5, 2.75, and 3.0. In comparison to the reference models (without underneath soil), the impacts of the examined parameters on the load-midspan deflection responses, cracking, and ultimate loads were investigated. Additionally, the associated settlements, stiffness, ductility, and energy dissipation capacity were also examined. The findings revealed that all RC pile caps exhibited a punching failure mode accompanied by shear cracks, irrespective of whether they were resting on sandy soil or not. On the contrary, the ultimate load of RC pile caps resting on sandy soil, especially with a higher relative density, was incredibly enhanced with respect to models loaded without supporting soil. The gain in the ultimate load of RC pile caps with S/D ratios of 2.25, 2.5, 2.75, and 3.0 was in the range of 5.4–6.7%, 12–16%, 15–21%, and 24–35%, respectively.

A Study on the Effects of Punch-to-Span Ratio and Longitudinal Reinforcement Eigenvalues on the Bearing Capacity of RC Slab–Column Connections

The region of the RC slab–column connection is subject to complex forces and is susceptible to localized damage, leading to progressive collapse incidents, which has raised considerable concern among the engineering community. At present, the research on slab–column connections exhibits several shortcomings, including a limited number of specimens, incomplete consideration of various factors, and unclear boundaries in defining failure modes. A comprehensive consideration of the punch–span ratio (a/h0) and longitudinal reinforcement eigenvalues (ρƒy/ƒc) is lacking, and the calculation formula for load bearing is not subdivided based on distinct failure modes. In this study, finite element software is utilized to construct 42 models of slab–column connections. The variables considered encompass three factors: the punch–span ratio, the longitudinal reinforcement ratio, and concrete strength. The examination and evaluation encompass the analysis of the load–displacement curve, reinforcement stress change curve, section crack distribution pattern, and stress contour map obtained through model loading. The primary parameters defining the boundaries of the three failure modes in the slab–column connection are the punch–span ratio and longitudinal reinforcement eigenvalues. Utilizing the punch–span ratio and longitudinal reinforcement eigenvalues as key parameters, a punching and flexural failure model for slab–column connections without abdominal bars is formulated. The calculation formula for bearing capacity, encompassing flexural, flexural and punching, and punching shear failure, is derived. A comparison between the revised formula and the standard formulas from major countries indicates that the revised formula is more comprehensive, providing a more accurate and secure prediction within the scope of this study.

Impact dynamic response of large aperture space deployable antenna supporting structures based on a dual-scale model

This study investigates the joint damage patterns and changes in shape accuracy of large aperture space deployable antenna supporting structures subject to hypervelocity impacts from micro space debris. Based on the dual-scale method, a joint scale model is constructed for a hexagonal prismatic space deployable truss antenna supporting structure with an aperture of six meters and 37 modules. ANSYS/AUTODYN is used for the impact damage analysis, with an equivalent model of impact force integrating the structure's actual damage characteristics in the structure scale model. The dynamic response and deformation performance of the antenna supporting structure under impact velocities from 2.5 to 15.0 km/s, with spherical space debris of 2.5 mm and 5.0 mm diameters, impacting modular central points in both positive and negative directions, are analyzed. The results show that the primary damage to the joint scale model after impact includes cratering, perforation, punch failure, and joint failure. The debris diameter significantly influences joint damage and deformation of the bolt hole diameter. Additionally, the debris cloud post-impact significantly affects the vertical bar's inner wall, spalling the wall and reducing the rod's strength. As the impact point moves towards the structure's centroid, the antenna's overall response increases. With higher impact velocities, the antenna supporting structure's overall deformation first increases, then decreases. At an impact velocity of 12.5 km/s, the impact area of the structure gradually reduces post-impact. Our proposed joint damage forms and three-case damage classification (no effect, repairable, and joint failure) may serve as a valuable reference for designing structural protection and impact identification for space deployable antennas.

Experimental response and numerical modelling of a full-scale two-span concrete slab frame subjected to blast load

Three full scale tests have been carried out on the same structure to determine the effect produced by several blast loadings detonated at different times. The structure is a two-span 7.00 × 14.00 m2 RC frame subjected to explosives load from 10 to 20 kg TNT equivalent at distances varying from 0.5 m to 1.5 m. The tests were monitored using pressures gauges, accelerometers, high-speed camera and a 3D topography scanner for measurement of permanent deflections. The test results show the robustness of the slab, with only minor cracking damage in the first two loading scenarios and only local damage in the third scenario, where the equivalent load of 20 kg TNT is placed only 50 cm from the slab surface. The third test produced maximum deflections of about 4 cm and a local punching failure measuring 66 cm in diameter on the upper face and 82 cm in diameter on the lower face. The simulation of the building was carried out with the LS-DYNA software with a Lagrangian formulation for the walls, using the Load Blast Enhanced (based on CONWEP) module. Permanent defections and damage has been evaluated and has been compared with numerical modelling.

Design of steel-concrete composite panels under low-velocity impact: Local punching failure

Steel-concrete composite panels (SC panels), consisting of two layers of steel plates and one layer of in-filled concrete, have excellent impact resistance. Currently, the proposed impact-resistant design methods of SC panels under low-velocity impact only consider the overall bending failure mode, but are unsuitable for the more common local punching failure mode. This study establishes an ideal tri-fold line resistance function and theoretically derives the stiffness and resistance of SC panels for the local punching failure mode. Furthermore, from the energy perspective, a design method is proposed in the study with impact-side steel plate tearing and SC panel penetration as safety criteria, and a design process covering two types of failure modes is provided. The design process is applied to the SC panel of the AP1000 nuclear station, and its practicality is validated, providing a simple tool for researchers and engineers.

Evaluation of impact response of thermal-damaged FRP-RC slabs: Effects of FRP bar type and concrete cover thickness

The purpose of present study is to investigate the impact response of FRP-RC slabs under elevated temperatures. Considering the high-temperature degradation effect and strain rate enhancement effect of FRP bars and concrete materials, a numerical model for studying the fire and impact resistance of FRP-RC slabs was established and verified. The impact failure mechanism of in-fire thermal-damaged FRP-RC slabs was analyzed. The influence of the type of FRP bars, concrete cover thickness and fire duration on the in-fire impact resistance of FRP-RC slabs was revealed. Ultimately, the post-fire residual bearing capacity of the slabs after elevated temperature and impact was obtained. The results show that the typical local punching failure mode is not affected by thermal damage while energy dissipated by concrete accounts for most of the impact energy absorbed by the slabs. When exposed to fire for 60 min, the elevated temperature significantly deteriorates the impact resistance of FRP-RC slabs with a cover thickness of 15 mm. At this time, the greater the concrete cover thickness, the better the impact resistance of FRP-RC slabs. Under the combined action of elevated temperature and impact, Carbon FRP-RC slabs have greater stiffness, lower deflection, greater impact plateau value, less impact duration and lower energy consumption than Aramid FRP, Basalt FRP and Glass FRP-RC slabs. Moreover, the damage index of the slab based on residual bearing capacity and peak displacement is approximately linearly positively correlated. The influence of the concrete cover thickness is more prominent on the damage index based on the peak displacement.

The effect of hybrid fiber and shear stud on the punching performance of flat-slab systems

In this paper, for the first time, the binary/ternary hybrid fiber and/or shear stud reinforcement as a measure was used to improve the punching performance of flat-slab systems by innovative self-compacting concrete (SCC). Because in these slab systems, sudden and brittle punching failure can be seen due to application and design errors, early removal of formwork, changes in the purpose of use of the building, earthquakes, etc. Besides, numerous studies investigated the punching performance of the single fiber and/or shear stud reinforced flat-slab systems, but research into the measures of the hybrid fiber or the combined use of hybrid fiber and shear stud reinforcement, which were the variable parameters of this study, was quite lacking. For this purpose, the half-scale slab-column connection elements were produced from SCC containing different punching measures (binary/ternary hybrid and/or shear stud) and tested to investigate the punching performance of flat-slab systems. In conclusion, it was found that hybrid fiber reinforcement was the best punching measure to improve the punching performance of slab-column connection elements with/out shear stud. Besides, 3D graphs were drawn so that designers and researchers could estimate the punching strength and energy absorption capacity for flat-slab systems with/out shear stud based on the parameters of micro fiber type and total volume fraction. On the other hand, empirical formulas were developed to predict the punching strength of binary/ternary hybrid fiber reinforced flat-slab systems with/out shear stud by compressive strength, fiber reinforcement index, the slab useful height, and the punching perimeter parameters.

Design for Disassembly of Concrete Slabs with Mortar Joints

A sustainable future is required for precast concrete structures, and the reuse of concrete elements will be an essential part of the solution. Design for disassembly is currently conducted with costly and time-consuming mechanical joints. Now, mortar joints with much weaker mortar types are proposed for new buildings, enabling easier disassembly by new methods: removal by direct pulling and removal by use of a system of flat jacks. Different weak mortar types were tested in the lab to achieve the properties required to check the transfer of wind loads and the level of resistance to separation during disassembly. Using a modelled case study building, the results showed that weak lime cement-based mortars had the required properties to substitute regular cement-based mortar in joints between slabs and a stabilising wall during a critical wind load. Regarding disassembly, pulling concrete slabs out with a mobile crane would be possible if hydro demolition systems could be implemented to remove parts of the mortar joint beforehand. Using a system of flat jacks to push the slab apart showed that the method’s weakness was the punching failure of the thin wall to the hollow cores. Solutions were proposed to overcome the challenge.

Effect of elevated temperature on the low-velocity impact performances of GFRP reinforced concrete slabs

The objective of the present study is to study the impact resistance of GFRP reinforced concrete slabs under elevated temperature. Considering the high temperature softening effect and strain rate enhancement effect of FRP bars and concrete materials, the numerical model for the study of fire and impact resistance of GFRP reinforced concrete slabs were established and compared with the fire resistance test and drop hammer impact test respectively, which verified the rationality of the numerical model. The failure mechanism of GFRP reinforced concrete slabs under the combined action of high temperature and impact loading was analyzed. The influence of fire scenario (at high temperature or after natural cooling) and fire time on GFRP reinforced concrete slabs was revealed. Eventually, the residual bearing capacity of damaged slabs after high temperature and impact loading was obtained. The results show that high temperature significantly degrades the impact resistance of GFRP reinforced concrete slabs. The slab at high temperature shows worse impact resistance than the slab after cooling down. With the increase of fire time, the punching failure of GFRP reinforced concrete slabs become more serious while the central displacement of the slabs and the impact duration increase, accompanied by decreased impact force. Compared with RC slabs, the deformation and impact force of GFRP reinforced concrete slabs under impact loading are more affected by high temperature, while the residual bearing capacity is less affected. Under the combined action of fire and impact loading, the slab is mainly local damage while energy dissipated by concrete accounts for most of the impact energy absorbed by the slabs.

Progressive collapse mode induced by slab-column joint failure in RC flat plate substructures: A new perspective

Majority of progressive collapse incidents of concrete flat plate structures were caused by slab overloading in the form of punching shear failure at a slab-column joint, which exhibit distinctive resistance mechanism from those triggered by column losses. Relevant studies on the slab overloading scenario are scarce. To fill this gap in research and to broaden the perspective on different collapse modes, an experimental test was conducted on a 1/3-scale 2 × 2-bay flat plate substructure specimen by applying an increased downward uniform load on the slab, until the structure was completely damaged following the initial punching shear failure at the interior slab-column joint and was unable to take any further load. In addition, the flexural capacity of the specimen was evaluated using the yield line theory, and an analytical model was also proposed to estimate the post-punching peak load of the specimen. Finally, the experimental results obtained from this study were compared to those of a similar test under an interior column removal scenario. Comparisons indicate that the specimen under the slab overloading scenario displays better collapse resistance than that under the column removal scenario. Nevertheless, the residual resistant capacity of the overloaded specimen may not be adequate enough to prevent the collapse of the entire structure after the initial punching failure.

Numerical Analysis on the Behavior of Floating Geogrid-Encased Stone Column Improved Foundation

The ordinary (OSC) and geosynthetic-encased stone column (ESC) with different bearing strata significantly influenced its behavior. The paper established seven models for studying the behavior of floating stone columns using the finite difference method (FDM). The effect of geogrid and column length on the load-settlement behavior, bulging deformation, failure mode, and load transfer coefficient were also analyzed based on proposal models. The results showed that the bearing capacity of F-OSCs and F-ESCs increased with the increase in column and encasement length, respectively, and a critical length (i.e., 4D, where D was the column diameter) was found in settlement improvement. The bulging deformation was significant in F-OSCs and was observed at the top of a long column and the full length of a short column. The geogrid encasement could constrain the OSC to decrease the bulging deformation. The failure mode in F-OSCs was mainly a punching failure with bulging deformation for a short column (e.g., less than 4D), and was relative to the vertical pressure for a long column. The failure mode in F-ESCs was a punching failure, and the punching degree increased with an increase in encasement length. The load transfer coefficient of F-OSCs or F-ESCs was relatively stable as the column length increased to a critical value (e.g., 4D) or the encasement length increased to a critical value (e.g., 4D).

Failure mechanism of one-way slabs under concentrated loads after local reinforcement yielding

One-way slabs under concentrated loads may fail by one-way shear such as wide beams, punching shear, flexure, or by combining two or more of these mechanisms. Nevertheless, most publications have only addressed shear and punching failures without flexural reinforcement yielding. This study investigates the ultimate shear capacity of one-way slabs under concentrated loads with local reinforcement yielding. In total, 12 tests were conducted on six reinforced concrete slabs. Simply supported slabs of 1.60 m × 3.40 m × 0.15 m were tested. Three parameters were varied: the load position, the span length and the reinforcement ratio. All slabs failed initially by punching with limited or extensive reinforcement yielding. Due to the relatively large amount of transverse reinforcement (0.44 %), most slabs underwent a large shear redistribution around the load, resulting in a wide beam shear failure after the local punching failure. The test results were compared to the theoretical predictions of shear, punching and flexure capacity using code expressions and the Extended Strip Model (ESM). The ESM resulted in the closest predictions of the experiments. These experiments confirm that a brittle shear and punching failure mechanism can occur even after extensive reinforcement yielding. Moreover, the results indicate that the ESM can be used to assess one-way slabs under concentrated loads with local reinforcement yielding.

Punching Shear Response Theory (PSRT) – A two degree of freedom kinematic theory for modeling the entire punching shear vs. deformation response of RC slabs and footings

Punching failures of reinforced concrete flat slabs and footings without shear reinforcement have been responsible for a number of catastrophic collapses. Despite intense scientific efforts in recent decades that have led to failure criteria-based phenomenological models, our current mechanistic understanding is still not sufficiently advanced to fathom the physical background of punching phenomena in RC structures. That is why, this paper proposes a novel two degree of freedom mechanical theory - called Punching Shear Response Theory (PSRT) - that interconnects all relevant effects of punching shear behavior, namely strutting action within a conical concrete shell at the slab-column interface, shear transfer actions elicited along the circumferential punching shear crack, including cohesive fracture process zone behavior, aggregate interlock and dowel action of reinforcement, as well as transfer of normal forces within tangential and radial cracks between slab segments in one all-encompassing algorithm. The PSRT can thoroughly mimic and efficiently reproduce the entire punching failure process of flat slabs and squat members (footings, pile caps, column bases) including prediction of pre- and post-peak punching shear vs. deformation response, quantification of different punching shear contributions and analysis of their evolution and mutual interaction within the failure process. The paper illustrates the analytical development of the PSRT, exemplifies its ability to reproduce the punching shear response of selected benchmark problems, proves its validity by database evaluations (incl. punching strength and deformation capacity) and eventually discloses the physical causalities of punching failures in RC structures.

PUNCHING SHEAR BEHAVIOR AND STRENGTH OF FLAT SLABS

Prestressed and reinforced concrete flat plates are susceptible to failure due to punching shear. Modeling the punching shear strength of prestressed concrete slabs poses conceptual challenges, as it involves various factors, including the bonding of tendons, stress in tendons during punching failure (which can be indeterminate), tendon banding, and the presence of draped tendons that yield a beneficial vertical component of the prestressing force. Additionally, prestressed concrete slabs typically require supplementary bonded reinforcement. The objective of this research is to comprehensively investigate the physical behavior of each test specimen, considering parameters such as deflections, crack patterns, crack widths, mode of failure, and to compare the punching shear resistance of interior slab-column connections with various code provisions. The study involved testing a total of five interior slab-column connections, each measuring 1600×1600 mm in size, 80 mm in thickness, with square columns of 180×180 mm and a height of 300 mm. Keywords: Slab, Punching, Shear, Design, Codes, prestressing.