scholarly journals CALCULATION OF RELIABILITY OF REINFORCED CONCRETE FLIGHT STRUCTURES

2021 ◽  
pp. 18-25
Author(s):  
Roman Kaplin
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Element Model ◽  
Operating Conditions ◽  
Structural Element ◽  
Reinforced Concrete Slab ◽  
Bridge Structures ◽  
Number Of Cycles ◽  
Office Software

A large number of bridges are operated on the roads of Ukraine. The increase in the intensity and speed of traffic leads to qualitative changes in the operating conditions of bridge structures, which is characterized by a sharp increase in the number of cycles under load of bridge elements, and to the development of damage in them. For trouble-free operation and efficient use of bridge structures it is very important to have reliable estimates of the actual load capacity and resource, taking into account the loads, material quality, nature of the structure. The solution of the problem in this statement is possible only on the basis of the theory of reliability. However, its application to specific assessments of durability and reliability of structures is associated with the solution of a set of issues: the identification of patterns of change of various parameters, the accumulation of reliable and easy to calculate statistics on loads and mechanical characteristics of materials, etc. It is necessary to know that the strength of the material (sample) of the structural element and the structure as a whole are completely different things. The article considers a new design of reinforced concrete girder structure, using perforated metal elements and an effective reinforced concrete slab of the carriageway. On its basis, a computational model in the form of a finite-element model built in the SCAD-Office software package is formed. As a result of calculations, the components of the stress-strain state of the structure are obtained. Based on the obtained results, the reliability of the structure was calculatedunder the influence of modern regulatory loads. 

Influence of the Parameter of Ductility of Reinforcing Steel on the Behaviour of a Narrow Three-Span Reinforced Concrete Slab Based on Experimental Investigations

2015 ◽  
Vol 240 ◽  
pp. 218-224 ◽  
Author(s):  
Mirosław Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Experimental Tests ◽  
Experimental Investigations ◽  
Building Structures ◽  
Reinforced Concrete Slab ◽  
Tension Member ◽  
Test Models ◽  
Reinforced Steel

In the time of the exploitation of building structures frequently situations do occur, in which due to failures they are exposed to much higher loads than has been originally predicted. In a state of emergency due to overloading of the structure, significant reserves of load capacity may be appear in the case of a self-acting tension member work. The aim of the paper was to demonstrate the influence of reinforced steel parameters and its quantity on the mechanism of destruction of four three-span models of reinforced concrete strips with the dimensions 7140×500×190 mm. The paper contains the description of the test stand and test models and the results of experimental tests which were compared with the results of the calculations based on traditional methods.

Theoretic-Strength Concept of a Model Describing the Destruction of the Corner Part of a Slab-Column Structure

2015 ◽  
Vol 240 ◽  
pp. 225-231 ◽  
Author(s):  
Mirosław Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Laboratory Tests ◽  
Concrete Slab ◽  
Load Capacity ◽  
Limit Load ◽  
Traditional Theory ◽  
Load Step ◽  
Reinforced Concrete Slab ◽  
Column Structure

The paper presents a proposed theoretical-strength destruction model of the corner of a slab-column structure at 1:2 scale. The theoretical destruction model was developed on the basis of laboratory tests of a reinforced concrete slab with the dimensions 4000×4000×100 mm. The assumptions of the proposed theoretical model were based on a traditional theory of behaviour of reinforced concrete constructions. The method for calculating the strength of reinforced concrete sections is based on interaction graphs of the load capacity NRd, MRd,x and MRd,y. The calculation method takes into account the influence of changes in the shape of the cross-section of the analysed element on its limit load capacity in every load step.

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.

Coupled Discrete Element/Finite Element Method for the Analysis of Large Reinforced Concrete Structures Submitted to an Impact

2011 ◽  
Vol 82 ◽  
pp. 284-289
Author(s):  
Laurent Daudeville ◽  
Jessica Haelewyn ◽  
Philippe Marin ◽  
Serguei Potapov
Keyword(s):  
Reinforced Concrete ◽  
Finite Elements ◽  
Heterogeneous Media ◽  
Concrete Slab ◽  
Element Model ◽  
Discrete Element ◽  
Discrete Elements ◽  
Reinforced Concrete Slab ◽  
The Impact ◽  
Element Method

The efficiency of the discrete element method for studying the fracture of heterogeneous media has been demonstrated, but it is limited by the size of the computational model. A coupling between the discrete elements (DEM) and the finite elements (FEM) methods is proposed to handle the simulation of impacts on large structures. The structure is split into two subdomains in each of which the method is adapted to the behavior of the structure under impact. The DEM takes naturally into account the discontinuities and is used to model the media in the impact zone. The remaining structure is modeled by the FEM. We propose an adaptation of the coupling procedure to connect Discrete Element model to shell-type Finite Elements. Finally, the efficiency of this approach is shown on the simulation of a reinforced concrete slab impacted by a tubular impactor.

scholarly journals Efficiency of ECE Applied on RC Slab using Locally Available Un-Galvanized Steel with Conductive Cement Paste Anode

2020 ◽  
Vol 9 (4) ◽  
pp. 1930-1936
Keyword(s):  
Reinforced Concrete ◽  
Cement Paste ◽  
Concrete Slab ◽  
Research Work ◽  
Chloride Content ◽  
Chloride Ions ◽  
Galvanized Steel ◽  
Current Intensity ◽  
Structural Element ◽  
Reinforced Concrete Slab

Electro-chemical Chloride Extraction (ECE) is considered one of the most effective technique used to extract chloride ions from reinforced concrete structures. Effectiveness of using ECE depends on some important factors such as anode type, current intensity, extraction duration, type of rebar and chemical properties of concrete. On the other hand, ECE may cause some detrimental effects on some mechanical properties of concrete and steel such as a reduction in bond and compressive strengths of concrete, and embrittlement (i.e. reduction in ductility) ductility of reinforcing steel. The major aim of this research work was to investigate the effectiveness of ECE using locally available un-galvanized steel mesh with conductive cement paste anode as a new type of anode on a reinforced concrete slab as a structural element. The slab behavior before and after ECE was studied by determining compressive strength, water absorption rate, concrete chloride content and steel corrosion potential. The slab behavior was studied taken into consideration the established steel arrangement with spacing 20 cm between re-bars. Another aim of this research work was to investigate the effect of initial chloride content on chloride extraction efficiency by applying optimum current intensity and duration (3 A/m2 and 6 weeks) on cylinders with pure chloride content 0.4% and 0.8% (by weight of cement). Effectiveness of ECE with small initial chloride content 0.4% and 0.8% was compared with that of high initial chloride content (2.5%) in order to know if the initial chloride content is an important factor on ECE effectiveness or not.

scholarly journals Enhancing the Punching Load Capacity of Reinforced Concrete Slabs Using an External Epoxy-Steel Wire Mesh Composite

Fibers ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 68
Author(s):  
Abdulkhaliq A. Jaafer ◽  
Raid AL-Shadidi ◽  
Saba L. Kareem
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Steel Wire ◽  
Wire Mesh ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Concentrated Load ◽  
Reinforced Concrete Slabs ◽  
Steel Wire Mesh

The present experimental work investigates the applicability and performance of a new strengthening method for concrete slabs, intended to increase their punching resistance using combination layers of steel wire mesh with epoxy attached to the concrete slabs’ tension face. Six simply supported square reinforced concrete slab specimens were tested up to failure under a central concentrated load. The main parameters in the study are the concrete compressive strength (30 MPa and 65 MPa) and the configuration of a bundle externally fixed to the tension side of the tested slabs. The experimental results appeared to greatly enhance the performance of the specimens, as they were externally strengthenined under this new method. When compared to the control slabs, the punching load and stiffness of the strengthened slabs increased up to 28% and 21%, respectively.

scholarly journals Finite element analysis of flexural behavior of textile reinforced concrete slab

2021 ◽  
Vol 261 ◽  
pp. 02042
Author(s):  
Mingqiu Xu ◽  
Jianhua Shao ◽  
Baijian Tang ◽  
Hongming Li
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Concrete Slab ◽  
Element Model ◽  
Flexural Behavior ◽  
Textile Reinforced Concrete ◽  
Reinforced Concrete Slab ◽  
Element Analysis ◽  
Bending Load

Order to investigate the failure effect of textile reinforced concrete (TRC) plate under bending load, the corresponding finite element model is established. By comparing the numerical simulation results with the experimental results, the rationality and feasibility of the finite element model are verified, and then the crack extension of TRC and the ultimate strain of carbon textile are analyzed. The failure mode of the slab under bending load is obtained, and it is found that the carbon textile concrete slab has better reinforcement effect, which greatly improves the safety performance of concrete members.

scholarly journals Protection of the slab-column structures against progressive collapse

2020 ◽  
Vol 310 ◽  
pp. 00051
Author(s):  
Barbara Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Laboratory Tests ◽  
Concrete Slab ◽  
Load Capacity ◽  
Progressive Collapse ◽  
Experimental Studies ◽  
Optimal Method ◽  
Reinforced Concrete Slab ◽  
Support Zone

The paper presents the problem of protection of reinforced concrete slab-column structures against the occurrence of a progressive collapse caused by punching in the support zone. The experimental studies and effects of recorded collapses indicate the necessity to use the appropriate reinforcement type, which will significantly increase the load capacity of the slab-column connection after punching. One of the ways to protect the structure is to use an integrity reinforcement as the most optimal method of strengthening. The contents explain the reasons for the application and description of issues related to this type of reinforcement. The conclusions from the use of this reinforcement based on the results of laboratory tests were presented.

scholarly journals Electrical Resistivity Measurements of Reinforced Concrete Slabs with Delamination Defects

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7113
Author(s):  
Kevin Paolo V. Robles ◽  
Dong-Won Kim ◽  
Jurng-Jae Yee ◽  
Jin-Wook Lee ◽  
Seong-Hoon Kee
Keyword(s):  
Electrical Resistivity ◽  
Reinforced Concrete ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Element Model ◽  
Concrete Slabs ◽  
Reinforced Concrete Slab ◽  
Resistivity Measurements ◽  
Reinforced Concrete Slabs ◽  
Concrete Resistivity

The main objectives of this research are to evaluate the effects of delamination defects on the measurement of electrical resistivity of reinforced concrete slabs through analytical and experimental studies in the laboratory, and to propose a practical guide for electrical resistivity measurements on concrete with delamination defects. First, a 3D finite element model was developed to simulate the variation of electric potential field in concrete over delamination defects with various depths and lateral sizes. Second, for experimental studies, two reinforced concrete slab specimens (1500 mm (width) by 1500 mm (length) by 300 mm (thickness)) with artificial delamination defects of various dimensions and depths were fabricated. Third, the electrical resistivity of concrete over delamination defects in the numerical simulation models and the two concrete slab specimens were evaluated by using a 4-point Wenner probe in accordance with AASHTO (American Association of State Highway and Transportation Office) T-358. It was demonstrated from analytical and experimental studies in this study that shallow (50 mm depth) and deep (250 mm depth) delamination defects resulted in higher and lower electrical resistivity (ER) values, respectively, as compared to measurements performed on solid concrete locations. Furthermore, the increase in size of shallow defects resulted in an increase in concrete resistivity, whereas the increase in sizes of deep delamination defects yielded opposite results. In addition, measurements done directly above the steel reinforcements significantly lowered ER values. Lastly, it was observed from experimental studies that the effect of delamination defects on the values of electrical resistivity decreases as the saturation level of concrete increases.

scholarly journals CRESTED SHEAR CONNECTORS APPLICATION TO COMBINE REINFORCED CONCRETE SLAB AND PLANK-NAILED STRUCTURE OF BRIDGE SPAN

2020 ◽  
Vol 17 (3) ◽  
pp. 414-427
Author(s):  
V. A. Utkin ◽  
I. I. Gotovtsev
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Beam Theory ◽  
Timber Structures ◽  
Bottom Part ◽  
Reinforced Concrete Slab ◽  
Composite Action ◽  
Shear Connectors ◽  
The Usa

Introduction. The construction of bridges using timber materials is experiencing a real boom throughout the world .The USA is considered to be a leader, where 80% of the bridges are made of timber or materials based on it. In Russia timber bridge construction has been stagnating for the last 50 years, although there is a need for these bridges. Timber structures could solve many problems with Russian roads, especially in remote areas. Timber structures are widely considered to be outdated, so they cannot meet current requirements of load capacity and durability, also they are vulnerable to atmospheric influences, etc. But foreign experience proves the contrary. The article is devoted to the implementation of new plank-nailed spans that meet current requirements of load capacity, reliability and durability.Materials and methods. The authors suggest and describe a new span structure. The span consists of planktimber- nailed-dowel blocks and a reinforced concrete slab generating a composite action. Some special crested shear connectors are suggested as combining elements. The top part works as flexible shear connectors in a reinforced concrete slab. The bottom part works as dowels with steel joints and timbers structures. The investigation of the stress-strain state of the structure has been completed within “compound beam” theory.Results. The application of the cast-in-place reinforced concrete slab allows to protect supporting timber structures against atmospheric influences, dirt, cracking from the sun rays, radiation and provides at least 50-year durability. The timber preservation provides a specified service life. The application of suggested connection with composite action between a reinforced concrete slab and supporting timber structures increases effectiveness of the composite timber concrete structure compared to steel and reinforced concrete structures. Trans-Baikal territory, Irkutsk and Arkhangelsk Regions, Khabarovsk Territory, the Republics of Sakha (Yakutia), Buriatia, Karelia are in the greatest need of the timber concrete composite spans, because they have a lot of forest resources and old timber bridges that are still in service.

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