scholarly journals Experimental Investigation of the Maximum Punching Resistance of Slab-Column Connections

2018 ◽  
Vol 26 (3) ◽  
pp. 22-28 ◽  
Author(s):  
Jaroslav Halvoník ◽  
Lucia Majtanová
Keyword(s):  
Experimental Investigation ◽  
Progressive Collapse ◽  
Transverse Reinforcement ◽  
Test Results ◽  
Structural System ◽  
Structural Behaviour ◽  
Shear Forces ◽  
Flat Slab ◽  
Direct Verification ◽  
Flat Slabs

Abstract Flat slabs represent a structural system with a typical concentration of shear forces near the vicinity of its local supports. A possible failure from punching is a dangerous phenomenon due to the brittleness and possible progressive collapse of a whole structure. An improvement in the structural behaviour of a slab-column connection provides transverse reinforcement. The amount of this reinforcement and thus its contribution to the resistance against punching has a limit, which is represented by the maximum punching capacity. This capacity can be assessed using the kmax factor or by direct verification of the strut capacity. The article deals with the results of a test campaign carried out on flat slab specimens with their transverse reinforcements designed in such a way that the crushing of the struts is the governing mode of any failure. The test results obtained allowed for an evaluation of the kmax factors and provide an answer as to whether it is possible to cover failures due to the crushing of struts by this factor.

scholarly journals NON-LINEAR ANALYSIS TO IMPROVE PUNCHING SHEAR STRENGTH IN FLAT SLAB USING Z-SHAPE SHEAR REINFORCEMENT

2019 ◽  
Vol 7 (1) ◽  
pp. 65-70
Author(s):  
Abdulnasser M. Abbas
Keyword(s):  
Shear Strength ◽  
Three Dimensional ◽  
Linear Analysis ◽  
Punching Shear ◽  
Stress Concentrations ◽  
Structural Behaviour ◽  
Shear Forces ◽  
Construction Time ◽  
Flat Slab ◽  
Non Linear

Currently, flat slabs become one of the widely used structures due to its architectural benefits such as uncomplicated formwork, flexibility and minimum construction time. However, these structures are relatively weak to resist the punching shear due to a considerable lowering in stiffness induced from the development of cracks that resulting from axial and seismic loads. Moreover, the punching failure is considered a brittle failure caused by the transferring of unbalanced moments and shear forces between the structural members. Unfortunately, this may cause a catastrophic collapse, especially in the region of the slab-column. Therefore, many experimental and theoretical studies were done to improve the punching strength of the flat slab. In the current work; a finite element three-dimensional non-linear analysis has simulated by ABAQUS tool to investigate the structural behaviour of flat slab. Two specimens have considered, the first is a flat slab reinforced by ordinary steel reinforcement. While in the second one, a Z-shape shear rebar improvement has been added to the slab-column connection. The proposed model has reflected a reasonable enhancement to the flat slab. The analysis considers different parameters such as punching shear forces, deformations, and stresses of Von-Mises. The outcomes indicate that punching shear strength is increased by approximately 11.1%, and the deflections are decreased by 77.3% when the Z-shape reinforcement is used. In the meantime, stress concentrations were reduced and move from the slab-column connection.

Safety of the Models for Assessment of Punching Resistance of Flat Slabs with Openings Adjacent to the Columns

2020 ◽  
Vol 309 ◽  
pp. 186-192
Author(s):  
Ľudmila Kormosova ◽  
Jaroslav Halvonik ◽  
Lucia Majtánová
Keyword(s):  
Standard Method ◽  
Design Model ◽  
Column Height ◽  
Transverse Reinforcement ◽  
Flat Slab ◽  
Flat Slabs ◽  
Current Design ◽  
Effective Depth ◽  
Effective Part

The paper deals with the quality of the current EC2 (2004) model for predicting punching capacity of flat slabs without transverse reinforcement, supported by elongated columns and weakened by two openings placed adjacent to the column. The ratio column’s section height/effective depth of a slab was six. The reference punching capacities were obtained from non-linear analyses carried out on the flat slab fragments. Five different arrangements of the openings were tested with three models that take into account an effect of the openings on the punching resistance. Based on the investigation performed, it was observed that the length 3d of the effective part of a column perimeter along the column height h with the ratio h/d > 3 is very conservative. The whole control perimeter contributed to the punching capacity for all slab fragments tested. Current design model EC2 (2004) is safe in the case of predicting the punching capacity of flat slabs with openings adjacent to the columns if the standard method of reduction of the control perimeter lengths due to openings is used. The most consistent results provided method that is based on the Augustin's proposal for reduction of the control perimeter length.

scholarly journals Punching shear in reinforced concrete flat slabs with hole adjacent to the column and moment transfer

2014 ◽  
Vol 7 (3) ◽  
pp. 414-467 ◽  
Author(s):  
D. C. Oliveira ◽  
R. B. Gomes ◽  
G. S. Melo
Keyword(s):  
Reinforced Concrete ◽  
Reinforcement Rate ◽  
Load Test ◽  
Punching Shear ◽  
Test Results ◽  
Flat Slab ◽  
Flat Slabs ◽  
Flexural Reinforcement ◽  
Hole Dimension ◽  
The Moment

The structural behavior and the ultimate punching shear resistance of internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column was investigated. Main variables were: the existence whether or not hole, flexural reinforcement layout and ratio, the direction and sense of the moment transferred and the eccentricity of the load (M (moment transferred to column) / V (shear)) ratio at the connection - 0,50 m or 0,25 m. Seven internal slab-column joining were tested and ultimate loads, cracking, deflections, concrete and reinforcement strains were analyzed. The existence of hole adjacent to the smaller column dimension, the hole dimension, flexural reinforcement rate and placing, the variation of relation Mu/Vu in function of the load, and, than, of eccentricity of the load, influenced the slabs behavior and rupture load. Test results were compared with the estimations from CEB-FIP/MC1990 [7], EC2/2004 [12], ACI-318:2011 [1] and NBR 6118:2007 [5]. ACI [1] and EC2 [12] presented most conservative estimates, although have presented some non conservative estimates. Brazilian NBR [5], even though being partly based in EC2 [12], presented smaller conservative estimates and more non conservative estimates. A modification on all codes is proposed for taking in account the moment caused by the eccentricity at the critical perimeter for slabs with holes.

Structural robustness of long-span cable-supported bridges segmented by zipper-stoppers to prevent progressive collapse

2018 ◽  
Author(s):  
Mohammad Shoghijavan ◽  
Uwe Starossek
Keyword(s):  
Analytical Approach ◽  
Good Accuracy ◽  
Numerical Models ◽  
Progressive Collapse ◽  
Structural System ◽  
Structural Behaviour ◽  
Load Bearing Capacity ◽  
Approximation Function ◽  
Long Span ◽  
Bridge Model

<p>This paper investigates the structural behaviour of a long-span cable-supported bridge segmented by zipper-stoppers after the sudden rupture of some of its cables. Increasing the robustness of the structural system through segmentation is a possible approach to prevent progressive collapse in bridges due to cable failure. In this concept, zipper-stoppers, at the segment borders, are strong components with the multiple of the load bearing capacity of usual members and are designed to arrest a zipper-like collapse in the segment where the initial damage occurred. For finding the “stress increase ratio” of the zipper-stopper, an analytical approach based on differential equations of the system will be used. Then, an approximation function for a simplified bridge model in a cable-loss scenario will be derived. The proposed approximation function has been checked by numerical models, and its good accuracy has been proven.</p>

scholarly journals Seismic Analysis of Flat Slab by using ETABS

2020 ◽  
Vol 9 (3) ◽  
pp. 1142-1144
Keyword(s):  
Seismic Analysis ◽  
Concrete Slab ◽  
Progressive Collapse ◽  
Design Procedure ◽  
Soil Condition ◽  
Soil Conditions ◽  
Reinforced Concrete Slab ◽  
Flat Slab ◽  
Analysis And Design ◽  
Flat Slabs

The flat slab is a two-way reinforced concrete slab that usually does not have beams and girders, and the loads are transferred directly to the supporting concrete columns. ETABS automates several slab and mat design tasks. Specially, it integrates slab design moments across design strips and designs the required reinforcement; it checks slab punching shear around column supports and concentrated loads; and it designs shear link and shear stud if needed. The actual design algorithms vary based on the specific design code chosen by the user. This manual describes the algorithms used for the various codes. Recent earthquakes in which many concrete structures have been severely damaged or collapsed, have indicated the need for evaluating the seismic adequacy of existing buildings. About 60% of the land area of our country is susceptible to damaging levels of seismic hazard. Many existing flat slab buildings may not have been designed for seismic forces. Hence it is important to study their response under seismic conditions and to evaluate seismic retrofit schemes. This system is very simple to construct, and is efficient in that it requires the minimum building height for a given number of stories. Unfortunately, earthquake experience has proved that this form of construction is vulnerable to failure, when not designed and detailed properly, in which the thin concrete slab fractures around the supporting columns and drops downward, leading potentially to a complete progressive collapse of a building as one floor cascades down onto the floors below. Although flat slabs have been in construction for more than a century now, analysis and design of flat slabs are still the active areas of research and there is still no general agreement on the best design procedure. To study the effect of drop panels on the behavior of flat slab during lateral loads, flat plate system is also analyzed. Zone factor and soil conditions- the other two important parameters which influence the behavior of the structure, are also covered. Software ETABS is used for this purpose. In this study relation between the number of stories, zone and soil condition is developed.

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.

The Analysis of Shear Forces Flow around the Supports of Flat Slabs

2020 ◽  
Vol 309 ◽  
pp. 216-221
Author(s):  
Simona Šarvaicová ◽  
Viktor Borzovič
Keyword(s):  
Cross Section ◽  
Shear Resistance ◽  
Linear Analysis ◽  
Punching Shear ◽  
Shear Forces ◽  
Flat Slab ◽  
Flat Slabs ◽  
Eurocode 2 ◽  
Non Linear ◽  
Linear Shear

This paper deals with both linear and non-linear analysis of shear forces distribution in the area near the supports of the flat slabs. With a cross-section ratio of cmax / cmin > 3, the main amount of the shear stress is concentrated near the column or wall corners bases. As a consequence of this phenomenon, it is necessary to reduce the control perimeter when evaluating the punching shear resistance of a flat slab. The fragments of the flat slabs with the thickness of 200 mm supported by a wall with various loading conditions were analyzed. The results according to the Eurocode 2 were compared to a non-linear shear resistance evaluation that was calibrated based on the results from the previous experiments. Based on thus evaluated punching shear resistances, the theoretical reduced control perimeter was determined and subsequently it was compared to design model Eurocode 2. The physical basis for determining reduced control perimeters is based on the shear force concentration near the support.

COMPUTATIONAL ANALYSIS OF METHODS FOR PROTECTING MONOLITHIC FRAMES OF MULTI-STOREY BUILDINGS WITH FLAT FLOORS FROM PROGRESSIVE COLLAPSE

2021 ◽  
Vol 96 (4) ◽  
pp. 35-44
Author(s):  
V.I. KOLCHUNOV ◽  
◽  
V.S. MOSKOVTSEVA ◽  
O.B. BUSHOVA ◽  
D.I. ZHUKOV ◽  
...  
Keyword(s):  
Computational Analysis ◽  
Progressive Collapse ◽  
Sudden Change ◽  
Structural System ◽  
Design Scheme ◽  
Design Load ◽  
Flat Slabs ◽  
Numerical Studies ◽  
Steel Consumption ◽  
Design Solutions

The paper presents new design solutions for the protection of monolithic frames of multi-storey buildings with flat floors from progressive collapse. At the same time, two variants of strengthening the support zones - the zones of coupling of the plate with the column, providing the perception of peak bending moments in the event of a sudden change in the force flows of the structural system caused by the removal of one of the supporting columns, are considered: the 1st variant-reinforcement with the use of metal insert plates, the 2nd variant - reinforcement with the use of support frames with inclined reinforcing rods. Numerical studies of a fragment of the considered monolithic frame of a building according to the primary design scheme for the effect of the design load and according to the secondary design scheme for the out-of-design impact show the effectiveness of the proposed design solutions for strengthening the interface zones of flat slabs with columns to protect the monolithic frames of buildings from progressive collapse. It is established that in the considered numerical example, the steel consumption when using the option of reinforcing the support zone with frames with inclined rods, other things being equal, is reduced to 46%.

Punching Resistance of Flat Slabs with Openings – Experimental Investigation

2018 ◽  
Vol 272 ◽  
pp. 41-46 ◽  
Author(s):  
Tomáš Augustín ◽  
Ľudovít Fillo ◽  
Jaroslav Halvonik ◽  
Marián Marčiš
Keyword(s):  
Experimental Investigation ◽  
Experimental Work ◽  
Material Properties ◽  
Laboratory Tests ◽  
Shear Resistance ◽  
Punching Shear ◽  
Shear Stresses ◽  
Flat Slab ◽  
Flat Slabs ◽  
Contemporary Architecture

Flat slabs are commonly used structures in contemporary architecture. Although their common use there is still problem in design of these structures. The openings adjacent to a column are often used for plumbing and such a position of the openings increases shear stresses in the flat slab near the column. This paper deals with experimental work focused on the punching shear resistance of the flat slab specimens with openings adjacent to column compared to the flat slab specimens without openings. The opening influence is determined experimentally and by using models for the assessment of punching resistance from relevant standards and codes. The material properties of concrete and reinforcing steel were obtained from the laboratory tests.

scholarly journals Experimental Investigation on Composite Deck Slab Made of Cold-Formed Profiled Steel Sheeting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 229
Author(s):  
Siva Avudaiappan ◽  
Erick I. Saavedra Flores ◽  
Gerardo Araya-Letelier ◽  
Walter Jonathan Thomas ◽  
Sudharshan N. Raman ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Test Results ◽  
Shear Connectors ◽  
Modes Of Failure ◽  
Deck Slabs ◽  
Load Carrying ◽  
Composite Slabs ◽  
Ultimate Load Carrying Capacity ◽  
Ductility Ratio ◽  
Deck Slab

An experimental investigation is performed on various cold-formed profiled sheets to study the connection behavior of composite deck slab actions using bolted shear connectors. Various profiles like dovetailed (or) re-entrant profiles, rectangular profiles and trapezoidal profiles are used in the present investigation. This experimental investigation deals with the evaluation of various parameters such as the ultimate load carrying capacity versus deflection, load versus slip, ductility ratio, strain energy and modes of failure in composite slab specimens with varying profiles. From the test results the performance of dovetailed profiled composite slabs’ resistance is significantly higher than the other two profiled composite deck slabs.

Sign in / Sign up

Export Citation Format

Share Document