Contribution of Settlement of a High-Rise Building with Recession in a Ground Plan to Punching Shear

2017 ◽  
Vol 259 ◽  
pp. 198-202
Author(s):  
Jan Nováček ◽  
Miloš Zich

Construction systems with recession in their ground plan along increasing height of a building are often used in current time. This lay-out is advantageous for the global stability of a building, which acts as a vertical cantilever with a widen socle. Attention must be paid with this type of global lay-out solution, because significant shear forces appear thanks to various types of grand plan. Usually buildings with massive elements, which can bear major of shear forces, don’t have any problem with the global vertical shear forces. Contrarily buildings with slight construction system such as flat slabs supported by columns could be unsafe designed if this effect is not taken account. There is no recommendation or exact approach to this problem in current standards and therefore it only depends on the designer’s approach and their experience. In the paper different types of approaches to the analysis of vertical shear forces and their distribution are presented. They are demonstrated on models with various levels of detailing. The scope of models starts at very simple linear model of whole structure and ends by models which take account of non-linear base supports and construction stages.

1990 ◽  
Vol 17 (4) ◽  
pp. 621-628
Author(s):  
Amin Ghali ◽  
Adel A. Elgabry

Gravity and horizontal forces cause the transfer of vertical shear and moments between concrete flat slabs and their supporting columns. These forces can cause punching failure. Design equations for safety against punching given in the Canadian Standards Association and the American Concrete Institute codes are critically reviewed. It is shown that the equations give in some cases incorrect stresses which do not satisfy equilibrium. A modification is suggested which makes the equations applicable to all cases. The paper also discusses the codes' approach of sharing the resistance to transferred moment between resistances by flexure and by eccentricity of shear, using the coefficient γv. Comparisons are made with the result of finite element analyses. It is concluded that the code equations, with the suggested modification, are adequate, provided that appropriate values are used for the coefficient γv. Key words: columns, connections, flat concrete plates, moments, punching shear, reinforced concrete, shear strength, slabs, structural design.


2020 ◽  
Vol 59 (1) ◽  
pp. 333-347
Author(s):  
Wajdi J. Baniya ◽  
Wael Zaki ◽  
C-M. Rabie Farrag ◽  
D- Ahmed Rashed

2015 ◽  
Vol 1106 ◽  
pp. 221-224
Author(s):  
Ľudovít Fillo ◽  
Jana Labudková ◽  
Ján Hanzel

Results of latest experiments have revealed that the maximum punching resistance defined from crushing of concrete struts at the perimeter of a column is an insufficient criterion for limitation of maximum shear forces at the vicinity of the columns. Therefore further limitation has been recommended by CEN TC250 SC2 and introduced in STN EN 1992-1-1/NA [1]. The paper will deal with the new requirements concerning the maximum punching shear resistance, based on the kmax factor and design of min flat slabs height.


2022 ◽  
Vol 253 ◽  
pp. 113671
Author(s):  
Victor Hugo Dalosto de Oliveira ◽  
Henrique Jorge Nery de Lima ◽  
Guilherme Sales Melo

2016 ◽  
Vol 691 ◽  
pp. 321-332
Author(s):  
Jan Nováček ◽  
Miloš Zich

Over the past few years, punching shear has been in the forefront of both research teams and professional public due to a new approach to its verification according to Model Code 2010. From this topic, the task of flat slabs strengthening against punching shear has arisen. This problem, and in particular the problem of flat slabs strengthened by additional concrete column heads, is the focus of this paper. Structures are analysed using a 3D FEM models including material and geometric nonlinearity. The way of modelling is validated against experiments on non-strengthened flat slabs subjected to punching shear. At first, strengthening with a rigid connection at the interface between structures is considered and then, several different types of connection at the interface are evaluated. Finally, strengthening of structures with varying lengths of top flexural reinforcement in the slab is modelled while minimum anchorage length outside the additional column head is verified.


2020 ◽  
Vol 309 ◽  
pp. 216-221
Author(s):  
Simona Šarvaicová ◽  
Viktor Borzovič

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.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 188
Author(s):  
Maciej Grabski ◽  
Andrzej Ambroziak

The scope of this paper is to investigate analytically and numerically the influence of shear cap size and stiffness on the distribution of shear forces in flat slabs in a slab–column-connections-reinforced concrete structure. The effect of support (shear cap) stiffness on the calculation of the length of the shear control perimeter according to the available methods is presented. Based on the analysis, the authors indicate in what range of support stiffness the corner concentrations become important in the calculation of the punching resistance. For shear caps with high flexibility (α1 ≤ 0.5), the concentration of internal forces in the corners does not occur. The authors compare the numerical results obtained from the calculation methods and indicate the correlations, which can be useful guidance for structural designers. In the case of large shear caps, the simplified MC2010 method gives a significantly lower value of the effective control perimeter length compared to more accurate methods. This paper is intended to provide scientists, civil engineers, and designers with guidelines on which factors influence punching shear load capacity of the slab–column connections with shear caps.


2011 ◽  
Vol 14 (1) ◽  
pp. 180-196
Author(s):  
A M Elshihy ◽  
H A ShehabEldeen ◽  
O Shaalan ◽  
R S Mahmoud

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