Numerical Modeling of Time-Dependent Deformations of Concrete at 3D Analysis of Structures

2020 ◽  
Author(s):  
◽  
Ante Džolan

Concrete is a material with highly nonlinear behavior. In parallel, there are numerous secondary effects in concrete, such as aging, shrinkage, and creep, which further complicate the realistic simulation of reinforced concrete and prestressed concrete structures. In modern times, due to bolder construction, increasing spans and high rising construction, the need for realistic simulation of the behavior of concrete structures under conditions of various types of loads is becoming more pronounced. On the other hand, models with a small number of real-life parameters that can describe the actual behavior of concrete as accurately as possible are necessary. One such model, the previously developed model Precon 3D, which is based on a small number of parameters and can very well describe the behavior of concrete, reinforced concrete and prestressed structures for short-term static loads was taken as the basis for this work. Through this work, the numerical model Precon 3D has been upgraded with a model for following the behavior of concrete during time, i.e. the model has been upgraded with a model of creep and shrinkage of concrete, which is necessary for following the behavior of prestressed structures. The developed software has been tested against several experimental examples from the literature, with a very good match between numerical and experimental results.

Author(s):  
K. E. Williamson

This paper is reproduced from the proceedings of a seminar on "Seismic Problems in Structural Engineering" arranged by the Departments of Civil Engineering and Extension Studies of the University of Canterbury, and held in Christchurch from May 13 
to 16, 1968. Another paper from that seminar, also published 
in this issue of the Bulletin, discusses requirements for ductility in reinforced concrete structures. The present 
paper makes a comparison of prestressed concrete with reinforced concrete, and discusses the factors to be considered 
in the design of prestressed structures for earthquake resistance.


2020 ◽  
Vol 309 ◽  
pp. 272-280
Author(s):  
Jiří Kolísko ◽  
Vítězslav Vacek ◽  
Petr Pokorný ◽  
Michaela Kostelecká

Steel reinforcement made of refined maraging steel in the form of wires and tendons has been for a long time used commonly for reinforcement of prestressed concrete structures. Defects on some of them and unfortunately even accidents of some cases of bridge objects, mainly recently published by media, related to corrosion of prestressed reinforcement awoke interest of both professional and wide non-professional public related to its durability. This issue also opens up a question of durability and liability of prestressed structures. In majority of existing prestressed structures the anticorrosion protection of reinforcement was traditionally secured mainly by alkalinity of the environment, i.e. concreting and/or grouting of prestressed elements in ducts. The abstract presents information related mainly to mechanical characteristics of corrosion-affected prestressed elements.


2020 ◽  
Vol 868 ◽  
pp. 57-64
Author(s):  
Vítězslav Vacek ◽  
Jiří Kolisko ◽  
Petr Pokorný ◽  
Michaela Kostelecká

Steel reinforcement made of refined maraging steel in the form of wires and strands has been for a long time used commonly for reinforcement of prestressed concrete structures. Defects on some of them and unfortunately even accidents of some cases of bridge objects, mainly recently published by media, related to corrosion of prestressed reinforcement awoke interest of both professional and wide non-professional public related to its durability. This issue also opens up a question of durability and liability of prestressed structures. In majority of existing prestressed structures the anticorrosion protection of reinforcement was traditionally secured mainly by alkalinity of the environment, i.e. concreting and/or grouting of prestressed elements in ducts. The abstract presents information related mainly to mechanical characteristics of corrosion-affected prestressed elements.


2021 ◽  
Vol 6 (12) ◽  
pp. 171
Author(s):  
Marco Andrea Pisani ◽  
Maria Pina Limongelli ◽  
Pier Francesco Giordano ◽  
Mattia Palermo

In this paper, the effectiveness of vibration-based tests for the detection of damages for prestressed concrete beams is investigated. Despite large research efforts, discrepant and sometimes contradicting conclusions have been drawn regarding the efficacy and reliability of vibration-based monitoring for prestressed structures. Herein, a contribution to this discussion is provided by tackling the problem from a different perspective. Specifically, the question that this paper intends to answer is: “Do vibration-based tests support decision-makers in integrity management operations for prestressed elements?” The discussion is carried out by comparing the performance of prestressed and ordinary reinforced concrete beams with similar capacities. Both analytical and numerical case studies are considered. Results show that, for prestressed beams, in contrast to reinforced concrete beams, modal parameters can provide information regarding damage only when the structure is close to its ultimate conditions. This makes this information hardly useful for integrity management purposes and the effectiveness of vibration-based tests questionable for this type of structural element.


Author(s):  
Sergey B. Krylov ◽  
Ravil S. Sharipov ◽  
Sergey A. Zenin ◽  
Yury S. Volkov

Design standards on building structures should contain, first of all, the performance and assessment requirements of structures. At the same time, design standards should provide the possibility for design and construction of concrete and reinforced concrete parts of buildings and structures that meet the requirements of the Technical regulations "On the safety of buildings and structures". Taking into account the importance of ensuring the reliability and safety of buildings and structures erected with the use of structural concrete, the technical Committee of the international organization for standardization ISO TC 71 "Concrete, reinforced concrete and prestressed concrete", certifies national standards for compliance with the requirements of the international standard ISO 19338 "Performance and Assessment Requirements for Design Standards on Structural Concrete", developed by the same Committee. The standard describes the issues that should be included in the standards for the design of concrete and reinforced concrete structures (terms and definitions, basic requirements, performance requirements,loads and impacts, design estimates, requirements for manufacturing and construction, as well as quality control). These requirements are common to all standards in the design of concrete and reinforced concrete structures. In this regard, it is relevant and important to establish the possibility of presenting the National Code of rules SP 63.13330.2012 "SNiP 52.01-2003 Plain and Reinforced Concrete Structures. General Provisions" for certification for compliance with the requirements of ISO 19338. To achieve this goal, the relevant work has been done, based on the results of which were made the proposals for the submission of SP 63.13330.2012 for certification for compliance with ISO 19338:2014. These proposals are set out in the text of the article.


2021 ◽  
Author(s):  
Reza Sadjadi

In reinforced concrete structures, failure of beam-column joint was observed as one of the major causes of damage of those structures during earthquakes. Non-ductile detailing of reinforcement in the joint in terms of inadequate shear reinforcement in the joint panel or insufficient anchorage of the beam bars within the joint region are the main causes of deficiency in the performance of joints during an earthquake. The objectives of this study are to compare different aspects of modeling the nonlinear behavior of exterior beam-column joints and also to propose a new model for the shear behavior of exterior joints. Two well-known computer programs for nonlinear dynamic analysis of the structures DRAIN-2DX (element type 15) and IDARC2D are used. The advantages of using each one for the beam-column joints in the reinforced concrete structures, and the effect of modeling features on the response of beam-column joints are discussed.


2021 ◽  
Author(s):  
Sorin Aslau

Corrosion is less frequent in prestressed concrete than in ordinary reinforced concrete, but when it does occur, the results can be more dangerous and more costly. In prestressed concrete structures the reinforcing steel elements are subjected to high mechanical stresses, therefore corrosion of the tendons can lead to catastrophic consequences, by the failure of the steel and consequently of structure, or part of it, with a great potential for life losses, life disruption, and a huge economical impact. One of the most dangerous aspects is that the corrosion related fracture of the steel might lead to a sudden collapse of the structure with little or no warning. The intention of this project report is to collect and synthesize information on the corrosion of the prestressing tendons as a mechanism of deterioration in prestressed concrete.


Sign in / Sign up

Export Citation Format

Share Document