scholarly journals An Analytical and Numerical Investigation on Punching Shear Behaviour of SCC Slab

2016 ◽  
Vol 3 (3) ◽  
Author(s):  
V. Kavinkumar ◽  
R. Elangovan
Keyword(s):  
Shear Stress ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Slab Thickness ◽  
Failure Zone ◽  
Self Compacting Concrete ◽  
Concentrated Load ◽  
Different Thickness

<div><p><em>This research is to study the mechanical properties of Self Compacting Concrete (SCC) as well as punching shear failure of SCC slabs. Self compacting concrete was first invited in 1988 to achieve durable concrete structures .Design of Reinforced concrete slab is often compromised by their ability to resist shear stress at punching shear surface area. The connection between slabs and supporting columns could be susceptible to high shear stress and might cause sudden and brittle failure. Punching shear failure takes the form of truncated pyramid shape. This program includes investigating the effect of SCC, slab thickness on the punching shear behaviour in terms of load-deflection response and ultimate failure load, failure characteristic of punching shear failure (shape of failure zone and size of failure zone) of simply supported slabs of 1000 x 1000 x 50 and 75mm under concentrated load at centre of slab. The slabs are made with both SCC and Conventional concrete (CC). Investigation included two way specimens with different thickness to evaluate the performance of specimen with different thickness and the effect of thickness on punching shear capacity and performance</em>.</p></div>

Tests of Slab-Column Connections Subjected to Reversed Cyclic Moments in Addition to Different Levels of Gravity Shear Load

2019 ◽  
Vol 292 ◽  
pp. 146-152
Author(s):  
Amr Abdelkhalik ◽  
Tamer Elafandy ◽  
Amr Abdelrahman ◽  
Alaa Sherif
Keyword(s):  
Cyclic Loading ◽  
Shear Failure ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Slab Thickness ◽  
Shear Reinforcement ◽  
Gravity Load ◽  
Rc Slab ◽  
Vertical Gravity ◽  
Punching Failure

Reinforced concrete flat slab-column structures are widely used because of their practicality. However, this type of structures can be subjected to punching-shear failure within the slab-column connections. Without shear reinforcement, the slab-column connection can undergo brittle punching failure, especially when the structure is subjected to lateral loading in seismic zones. This research is a part of an extensive investigation about the punching shear behaviour of interior RC slab-column connections under seismic loading. The main objective is to discuss the effect of the gravity shear level on the punching shear behaviour[1].The current paper represents only the results of the first four tested specimens without shear reinforcement. The first specimen was tested subjected to vertical gravity load only without cyclic loading while the other three specimens were tested under different vertical loads V which was kept constant during testing in addition to a reversed displacement controlled cyclic loading which was increased up to punching shear failure. The gravity load V was chosen as 0.4, 0.6 and 0.8 V0 respectively, where V0 is the vertical load causing punching shear failure according to ACI318-14[2]. All tested specimens have the same slab dimensions of 2000x2000mm, slab thickness 200mm, flexural reinforcement ratio of 1.62% and the same column dimensions 250mm x 250mm. Finally, the experimental results are analyzed and compared to international codes such as American Code ACI318-14 and Euro Code EC2-2004[3]. In light of these results, some preliminary conclusions are presented.

A REVIEW TO PUNCHING SHEAR CAPACTY OF NORMAL AND HIGH PERFORMANCE FIBER CEMENTIOUSE COMPOSITES

2021 ◽  
Vol 25 (Special) ◽  
pp. 4-115-4-126
Author(s):  
Liwaa Abd Alhussen ◽  
◽  
Layth A. Al-jaberi ◽  
Ra’id F. Abbas ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Shear Failure ◽  
High Performance Concrete ◽  
Shear Capacity ◽  
Punching Shear ◽  
Concrete Slabs ◽  
Slab Thickness ◽  
Shear Stresses ◽  
Reinforced Concrete Slabs

The reaction of column to flat slabs may cause what is known as “punching shear stresses” when the stress is normally concentrated within the perimeter around the loaded area. In general, the reinforced concrete slabs are not designed for any shear failure due to the sudden nature of this type of failure. Many solutions can be followed to overcome such issue like increasing the depth of slab and diameter of columns. Increasing the slab thickness may add extensive dead loads and can breaks the economy justifications of this structural member. On the other hand, increasing the diameter of any column may un accepted due to architectural purposes. The high performance concrete is such type of concrete that illustrate high levels of mechanical performance “structural behavior as a consequence” if compared with normal concrete. Due to that, the high performance concrete may give good alternative an exceeds the problem of punching as a result. The basic aim of this study is to propose a brief review regarding this field of research. However, this study is divided to three parts, the first is devoted to view a suitable background about the punching shear capacity of traditional concrete slabs. The second part is registered to view the past experience in reinforced concrete slabs punching capacity and have steel fibers while the second part is devoted to present the state of art concerning the punching shear of high performance concrete slabs.

scholarly journals Performance of Shear Reinforcement against Punching Shear Loads

2019 ◽  
Vol 9 (2) ◽  
pp. 841-850
Keyword(s):  
Numerical Study ◽  
Shear Capacity ◽  
Punching Shear ◽  
Slab Thickness ◽  
Test Results ◽  
Shear Reinforcement ◽  
Concentrated Load ◽  
Flat Slab ◽  
Flat Slabs ◽  
Strength Formula

This research targets to maximize the ductility and strength of the reinforced concrete flat slabs. However, to be efficient, the shear reinforcement must be anchored well in the tension and compression zones of the slab. The test results on the slab-column connection models which provided with shear reinforcement are introduced in this study. The benefits of using shear reinforcement are to reduce the slab thickness, and to minimize both the cost and the total weight of the structure. Twelve flat slab specimens have been tested to study the effect of different types of steel RFT on the punching shear of the flat slab. The experimental parameters include no shear reinforcement which study the advantage of using tension RFT ONLY against punching shear, no shear reinforcement which study the advantage of using compression RFT against punching shear, shear RFT (Vertical Stirrups) which study the effect of using shear RFT with constant distribution 0.5d, and a new distribution of shear stirrups which study the effect of using new different width & spacing of vertical stirrups. The twelve specimens were loaded with concentrated load at the mid span until failure. The general behavior of the deformation of the tested slab specimens was examined and recorded (cracking, deflection, and strain in both steel and concrete). A comparison established between the experimental and the numericaltheoretical results obtained from applying the punching shear strength formula given in design codes, and finite element modeling analysis; ABAQUS 2017 software package was used for this analysis. A total of six building codes were examined with regard to their provisions concerning the punching shear. A comparison had been made between the research test results and the codes equations to improve the methods of the analysis about the flat slabs. This study aimed to improve the punching shear capacity of flat slab which leads to more accurate results compared with the codes predictions. To achieve this aim, an experimental and numerical study was carried out for this investigation.

Punching shear behaviour of flat slabs with different reinforcement schemes: openings and rectangularity effects

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Donia Salman ◽  
Rabab Allouzi ◽  
Nasim Shatarat
Keyword(s):  
Structural Engineering ◽  
Experimental Tests ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Cross Sectional ◽  
Content Type ◽  
Flat Slabs ◽  
Reinforced Concrete Slabs ◽  
Rectangular Columns

PurposeThe main goal is to investigate the effect of size and location of opening and column size on the punching shear strength. Openings are often needed in order to install mechanical and electrical services. This process takes away part of the concrete volume which is responsible for resisting the shear forces and any unbalanced moment. Furthermore, the application of rectangular columns in flat slabs is commonly used in practice as they provide lateral stiffness to the building. They are also utilised in garages and multi-storey buildings where these elongated cross-sectional columns reduce the effective span length between adjacent columns.Design/methodology/approachThis research is a numerical-based investigation that is calibrated based on a thirteen previously tested and numerically calibrated slab specimens with no openings. A parametric study is conducted in this study to consider the effect of other parameters, which are the size and location of opening and the rectangularity ratio of column in order to evaluate their effect on the punching shear capacity. A total of 156 models are developed to study these factors. Additionally, the predicted shear carrying capacity of the simulated slabs is calculated using the ACI318–19 and Eurocode (EC2-04) equation.FindingsThe presence of openings reduced the punching shear capacity. The small opening's location and orientation have almost no effect except for one slab. For slabs of large openings, the presence of openings reduced the punching capacity. The punching capacity is higher when the openings are farther from the column. The numerically obtained results of slabs with rectangular columns show lower punching capacity compared to slabs of squared columns with the same length of the punching shear control perimeter. The punching capacity for all slabs is predicted by ACI318–19 and Eurocode (EC2-04) and it is found that Eurocode (EC2-04) provided a closer estimation.Originality/valueThe slabs considered for calibration were reinforced with four different punching shear reinforcement configurations, namely; ordinary closed rectangular stirrups, rectangular spiral stirrups, advanced rectangular spiral stirrups and circular spiral. Generally, there has been limited research on concrete flat slabs with openings in comparison with other subjects related to structural engineering (Guan, 2009) and no research on punching shear with openings of slabs reinforced with these reinforcement schemes. The available research focussed on the effects of openings on the flexural behaviour of reinforced concrete slabs includes Casadei et al. (2003), Banu et al. (2012) and Elsayed et al. (2009). In addition, experimental tests that examined slabs supported on rectangular columns are very limited.

Study on Shear Behaviour of Concrete Beams Prestressed with External CFRP Tendons

2013 ◽  
Vol 275-277 ◽  
pp. 1167-1171
Author(s):  
Xin Ding Wang ◽  
Hang Dai ◽  
Yong Chao Zhang
Keyword(s):  
Shear Failure ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Shear Behaviour ◽  
Similar Process ◽  
Shear Span ◽  
External Tendons ◽  
Straight Line ◽  
Steel Bars

Based on independent research and development of a CFRP tendons wedge-type anchorage, the shear tests of six CFRP external prestressing concrete beams were done. Among them, CFRP external tendons of three pieces were installed in straight line while other pieces were installed in curved line. The results of experimental research show that shear behaviour of concrete beams prestressed with CFRP external tendons are the similar process to the traditional prestressed reinforced concrete beams. They go through the elastic stage, the stage of crack extension, the yield stage of internal hoop reinforcements at the intersection of inclined cracks and the failure stage. When external CFRP tendons are arranged in the same situation, the cracking load and the shear capacity of concrete beams prestressed with CFRP external tendons reduce gradually along with the increase of shear-span ratio,.When shear-span ratio is equal, the cracking load and the shear capacity of concrete beams prestressed with curved arrangement of CFRP external tendons are larger than those of concrete beams prestressed with straight arrangement of CFRP external tendons. Compared with traditional concrete beams prestressed with external steel bars, due to elasticity modulus and shear modulus of CFRP tendons are both smaller than those of steel bars, the mid-span deflection of concrete beams prestressed with CFRP external tendons at the time of shear failure is bigger than that of traditional concrete beams prestressed with external steel bars under the same circumstance.

Design of shear reinforcement for thick plates using a strut-and-tie model

2010 ◽  
Vol 37 (2) ◽  
pp. 181-194 ◽  
Author(s):  
H. Marzouk ◽  
E. Rizk ◽  
R. Tiller
Keyword(s):  
Shear Failure ◽  
Punching Shear ◽  
Shear Behaviour ◽  
Rational Approach ◽  
Concrete Slabs ◽  
Shear Reinforcement ◽  
Lower Section ◽  
Strut And Tie ◽  
Shear Cracking ◽  
Strut And Tie Model

The strut-and-tie method is a rational approach to structural concrete design that results in a uniform and consistent design philosophy. A strut-and-tie model has been developed to model the punching-shear behaviour of thick concrete plates. This model provides a quick and simple approach to check the punching-shear behaviour. Thick concrete slabs (250–500 mm) without shear reinforcement can exhibit brittle shear failure under a central force and an unbalanced moment. Shear reinforcement has proven to be very effective in preventing such failures. The developed strut-and-tie model has also been used to evaluate the minimum shear reinforcement required to prevent brittle shear failure of two-way slabs in the vicinity of concentrated loads. The strut-and-tie model for symmetric punching consists of a “bottle-shaped” compressive zone in the upper section of the slab depth, leading to a “rectangular-stress” compressive zone in the lower section of the slab depth. Inclined shear cracking develops in the bottle-shaped zone prior to failure in the lower zone. Cracking in the bottle-shaped zone is related to the splitting tensile strength of concrete.

scholarly journals Shear Behaviour of Reinforced Self-Compacting Concrete Beams Made with Treated Recycled Aggregate

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Doaa H. Al-Jasimee ◽  
M.S. Abo Dhaheer
Keyword(s):  
High Strength ◽  
Treatment Method ◽  
Shear Capacity ◽  
Recycled Aggregate ◽  
Shear Behaviour ◽  
Structural Performance ◽  
Self Compacting Concrete ◽  
Ultimate Failure ◽  
Normal Strength ◽  
Cracking Pattern

In this paper, an experimental work was conducted to investigate the possibility of improving the structural performance of reinforced self-compacting concrete (SCC) beams cast with 100% treated and untreated recycled aggregate (RA). RA was first exposed to a simple treatment method to reduce the amount of its adhered mortar and to improve its performance by the impregnation in polyvinyl alcohol (PVA) polymer solution. After completing RA treatments, rectangular simply supported reinforced SCC beams cast with RA, treated recycled aggregate (TRA) as well as normal aggregate (NA), were prepared and tested under two-point loading up to failure. Half of the prepared beams were tested to evaluate the shear behaviour of normal strength (NS) SCC mixes, while the other half was tested for high strength (HS) SCC mixes. The results were evaluated with regards to load deflection response, ultimate failure load, first crack load, and cracking pattern. The main experimental results demonstrated that using treated RA considerably improved the shear capacity of reinforced SCC beams in comparison with that of untreated RA. Based on the ACI 318-14 and Euro codes, the shear strength values showed that the treated RA beams were considered more conservative compared to the RA beams in both strength grades.  

scholarly journals New Methods to Resisting Punching Shear Stress in Reinforced Concrete Flat Slabs

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
Fatma M. Eid ◽  
Tayel Magdy ◽  
Ebada Ahmed
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Reinforcement System ◽  
Strength Concrete ◽  
Flat Slabs ◽  
The Difference ◽  
Compact Strength

Punching shear failure is a major problem encountered in the design of reinforced concrete flat slabs. The utilization of shear reinforcement via shear studs or other means has become a choice for improving the punching shear capacity. In this study, a new alternative of reinforcement modalities were tested and demonstrated the effect of self-compact concrete on the punching shear capacity, beside that compared between the difference codes to identify the suitable one for determining the position of critical section of punching shear. Nevertheless, in this investigation, the proposed reinforcement system is examined for interior columns only. An experimental work consisting of six specimens: five of them were cast with normal reinforced concrete and one was cast with self-compact strength concrete. The obtained results indicate that the proposed shear reinforcement system has a positive effect in the enhancement of the punching shear capacity of interior slab–column connection of self-compact strength concrete.

scholarly journals Investigations of Coal-Rock Parting-Coal Structure (CRCS) Slip and Instability by Excavation

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Guang-Jian Liu ◽  
Heng Zhang ◽  
Ya-Wei Zhu ◽  
Wen-Hao Cao ◽  
Xian-Jun Ji ◽  
...  
Keyword(s):  
Shear Failure ◽  
P Wave ◽  
Shear Behaviour ◽  
Failure Zone ◽  
Stick Slip ◽  
Coal Structure ◽  
P Wave Velocity ◽  
Splitting Failure ◽  
Shear And Tensile Cracks ◽  
Coal Rock

Slip and instability of coal-rock parting-coal structure (CRCS) subjected to excavation disturbance can easily induce coal-rock dynamic phenomena in deep coal mines. In this paper, the failure characteristics and influencing factors of CRCS slip and instability were investigated by theoretical analysis, numerical simulations, and field observations. The following main results are addressed: (1) the slip and instability of CRCS induced by excavation are due to stress release, and the damage of the rock parting is partitioned into three parts: shear failure zone, slipping zone, and splitting failure zone from inside to outside with slip; (2) the slip and instability process of CRCS is accompanied by initiation, expansion, and intersection of shear and tensile cracks. The development of the cracks is dominated by shear behaviour, while the tensile crack is the main factor affecting fracture and instability of CRCS; and (3) slip and instability of CRCS are characterized by stick-slip first and then stable slip, accompanied with high P-wave velocity and rockburst danger coefficient based on microseismic tomography.

scholarly journals Resisting punching shear stress in reinforced concrete slabs

2018 ◽  
Vol 162 ◽  
pp. 04025
Author(s):  
Ebada Ahmed ◽  
Boshra Eltaly ◽  
Fatma El-Zhraa ◽  
Magdy Tayel
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Shear Capacity ◽  
Punching Shear ◽  
Shear Reinforcement ◽  
Reinforcement System ◽  
Strength Concrete ◽  
Reinforced Concrete Slabs ◽  
The Difference ◽  
Compact Strength

Punching shear failure is a major problem encountered in the design of reinforced concrete flat slabs. The utilization of shear reinforcement via shear studs or other means has become a choice for improving the punching shear capacity. In this study, a new alternative of reinforcement modalities were tested and demonstrated the effect of self-compact concrete on the punching shear capacity, beside that compared between the difference codes to identify the suitable one for determining the position of critical section of punching shear. Nevertheless, in this investigation, the proposed reinforcement system is examined for interior columns only. An experimental work consisting of six specimens: five of them were cast with normal reinforced concrete and one was cast with self-compact strength concrete. The obtained results indicate that the proposed shear reinforcement system has a positive effect in the enhancement of the punching shear capacity of interior slab–column connection of self-compact strength concrete.

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