DYNAMICS OF REINFORCED CONCRETE NON-BEAM FRAMES IN CASE OF DAMAGE TO SLABS PUNCHING

2021 ◽  
Vol 96 (4) ◽  
pp. 23-34
Author(s):  
A.V. ALEKSEYTSEV ◽  
◽  
M.D. ANTONOV ◽  
Keyword(s):  
Reinforced Concrete ◽  
Energy Method ◽  
Dynamic Process ◽  
Geometric Nonlinearity ◽  
Strain State ◽  
Concrete Slab ◽  
Dynamic Effects ◽  
Reinforced Concrete Slab ◽  
Static Assessment ◽  
Emergency Actions

An approach to the assessment of dynamic effects for reinforced concrete non-beam frames of structures under combined emergency actions is considered. Primary impacts imply an excess of operational loads, which causes damage to the slab-column junction from punching to the onset of a secondary impacts. Secondary impacts include considering the removal of any column from the design model over a finite time. The analysis of dynamic effects based on two approaches: the first is based on the energy method of G.A. Geniev and assumes a quasi-static assessment of the stress-strain state of the damaged system; the second is the analysis of the transient dynamic process taking into account physical and geometric nonlinearity. An approximate approach to modeling the damage of a reinforced concrete slab from punching is proposed and further prospects for its improvement are considered. The degree of danger at emergency impacts for structures pre-damaged by punching, as well as the influence of these damages on the survivability of frames under these effects, has been established. An example of assessing survivability on a model of an underground parking frame in the presence of damage from punching for one of the column-slab joints is considered.

scholarly journals Finite Difference Energy Method for nonlinear numerical analysis of reinforced concrete slab using simplified isotropic damage model

2014 ◽  
Vol 7 (6) ◽  
pp. 940-964
Author(s):  
M. V. A. Lima ◽  
J. M. F. Lima ◽  
P. R. L. Lima
Keyword(s):  
Reinforced Concrete ◽  
Finite Difference ◽  
Energy Method ◽  
Virtual Work ◽  
Concrete Slab ◽  
Damage Model ◽  
Flexural Behavior ◽  
Structural Element ◽  
Reinforced Concrete Slab ◽  
Reinforced Concrete Slabs

This work presents a model to predict the flexural behavior of reinforced concrete slabs, combining the Mazars damage model for simulation of the loss of stiffness of the concrete during the cracking process and the Classical Theory of Laminates, to govern the bending of the structural element. A variational formulation based on the principle of virtual work was developed for the model, and then treated numerically according to the Finite Difference Energy Method, with the end result a program developed in Fortran. To validate the model thus proposed have been simulated with the program, some cases of slabs in flexure in the literature. The evaluation of the results obtained in this study demonstrated the capability of the model, in view of the good predictability of the behavior of slabs in flexure, sweeping the path of equilibrium to the rupture of the structural element. Besides the satisfactory prediction of the behavior observed as positive aspects of the model to its relative simplicity and reduced number of experimental parameters necessary for modeling.

Bending Effect On The Mechanism Of Punching The Support Zone Of The Reinforced Concrete Slab

2019 ◽  
pp. 20-28
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Strain State ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Reinforced Concrete Structure ◽  
Stress Strain ◽  
Reinforced Concrete Slab ◽  
Stress Strain State ◽  
Reinforced Concrete Slabs

The analysis of various regulatory methods for calculating reinforced concrete slabs for punching and comparing with experiment results is made. The tested sample, measuring equipment and test bench are described. Dimensions and materials for the production of the prototype were chosen on the basis of experience in the construction of girderless and capless regular monolithic reinforced concrete frames. The results of experimental studies of a fragment of a slab reinforced concrete structure in order to study the stress-strain state, when implementing the mechanism of punching, are presented. The results of observations obtained during the tests are presented. A comparison of the nature of operation of the tested fragment of the slab with the nature of operation of the full-fledged construction is given. A comparative analysis of the stress-strain state of the tested sample and the results of the calculation of the bearing capacity for punching according to various normative methods is performed. According to the results of the experiment, the main criteria determining the implementation of the punching mechanism are established, and a new method for calculating girderless floors is proposed on the basis of a fundamentally different approach in determining the bearing capacity.

scholarly journals The effect of cracks on the bearing capacity of reinforced concrete slabs

2019 ◽  
Vol 97 ◽  
pp. 03001
Author(s):  
Vladimir Agapov
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Strain State ◽  
Concrete Slab ◽  
Physical Nonlinearity ◽  
Concrete Slabs ◽  
The Finite Element Method ◽  
Reinforced Concrete Slab ◽  
Reinforced Concrete Slabs ◽  
Composite Fabrics

Cracks occur in reinforced concrete slabs for two reasons - due to increased operational loads and due to manufacturing and installation defects. When cracks are detected, the question arises about the residual bearing capacity of the slab and the need of its strengthening. To solve this problem by calculation, it is necessary to take into account physical nonlinearity. An algorithm for the calculation by the finite element method is proposed. The main feature of the algorithm is the use of multilayered finite elements, which allows modeling the cracks by specifying the corresponding material characteristics of those layers which the crack passes through. A method for determining the bearing capacity of a slab with cracks after its reinforcement with composite fabrics is also considered. An example of the study of the stress-strain state of a reinforced concrete slab with cracks by the proposed method is given. The implementation of the algorithm in the PRINS program is described and the possibility of using this program for solving practical problems is discussed.

Dimension and Frequency Profiles of Concrete Highway Bridges in New Madrid Region of Southeastern Missouri

1997 ◽  
Vol 1594 (1) ◽  
pp. 84-93 ◽  
Author(s):  
Ralph Alan Dusseau
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Highway Bridges ◽  
Ambient Vibration ◽  
Earthquake Hazards ◽  
Empirical Formulas ◽  
Reinforced Concrete Slab ◽  
Box Girder ◽  
Bridge Spans ◽  
New Madrid

The results of a study funded by the U.S. Geological Survey as part of the National Earthquake Hazards Reduction Program are presented. The first objective of this study was the development of a database for all 211 highway bridges along I-55 in the New Madrid region of southeastern Missouri. Profiles for five key dimension parameters (which are stored in the database) were developed, and the results for concrete highway bridges are presented. The second objective was to perform field ambient vibration analyses on 25 typical highway bridge spans along the I-55 corridor to determine the fundamental vertical and lateral frequencies of the bridge spans measured. These 25 spans included six reinforced concrete slab spans and two reinforced concrete box-girder spans. The third objective was to use these bridge frequency results in conjunction with the dimension parameters stored in the database to develop empirical formulas for estimating bridge fundamental natural frequencies. These formulas were applied to all 211 Interstate highway bridges in southeastern Missouri. Profiles for both fundamental vertical and lateral frequencies were then developed, and the results for concrete highway bridges are presented.

An Assessment of the Long-Term Durability of Concrete in Radioactive Waste Repositories

1985 ◽  
Vol 50 ◽  
Author(s):  
A. Atkinson ◽  
D. J. Goult ◽  
J. A. Hearne
Keyword(s):  
Reinforced Concrete ◽  
Radioactive Waste ◽  
Concrete Slab ◽  
Laboratory Studies ◽  
Preliminary Assessment ◽  
Reinforced Concrete Slab ◽  
Radioactive Waste Repositories ◽  
Waste Repositories ◽  
Durability Of Concrete

AbstractA preliminary assessment of the long-term durability of concrete in a repository sited in clay is presented. The assessment is based on recorded experience of concrete structures and both field and laboratory studies. It is also supported by results of the examination of a concrete sample which had been buried in clay for 43 years.The enoineering lifetime of a 1 m thick reinforced concrete slab, with one face in contact with clay, and the way in which pH in the repository as a whole is likely to vary with time have both been estimated from available data. The estimates indicate that engineering lifetimes of about 103 years are expected (providing that sulphate resisting cement is used) and that pH is likely to remain above 10.5 for about 106 years.

Sign in / Sign up

Export Citation Format

Share Document