scholarly journals Heating Temperature Prediction of Concrete Structure Damaged by Fire Using a Bayesian Approach

2020 ◽  
Vol 12 (10) ◽  
pp. 4225
Author(s):  
Hae-Chang Cho ◽  
Sun-Jin Han ◽  
Inwook Heo ◽  
Hyun Kang ◽  
Won-Hee Kang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Elevated Temperatures ◽  
Heating Temperature ◽  
Model Development ◽  
Estimation Model ◽  
Temperature Estimation ◽  
Rc Structures ◽  
Material Development ◽  
Rc Structure ◽  
Eurocode 2

A fire that occurs in a reinforced concrete (RC) structure accompanies a heating temperature, and this negatively affects the concrete material properties, such as the compressive strength, the bond between cement paste and aggregate, and the cracking and spalling of concrete. To appropriately measure the reduced structural performance and durability of fire-damaged RC structures, it is important to accurately estimate the heating temperature of the structure. However, studies in the literature on RC structures damaged by fire have focused mostly on structural member tests at elevated temperatures to ensure the fire resistance or fire protection material development; studies on estimating the heating temperature are very limited except for the very few existing models. Therefore, in this study, a heating temperature estimation model for a reinforced concrete (RC) structure damaged by fire was developed using a statistical Bayesian parameter estimation approach. For the model development, a total of 77 concrete test specimens were utilized; based on them, a statistically highly accurate model has been developed. The usage of the proposed method in the framework of the 500 °C isotherm method in Eurocode 2 has been illustrated through an RC column resistance estimation application.

scholarly journals Effects of Tension Reinforcement Ratio on Ductility of Mid-Rise Reinforced Concrete Structures

2018 ◽  
Vol 1 (1) ◽  
pp. 702-708
Author(s):  
Onur Onat ◽  
Burak Yön
Keyword(s):  
Reinforced Concrete ◽  
Failure Mode ◽  
Concrete Structures ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Beam Elements ◽  
First Case ◽  
Rc Structure ◽  
Determine Effect

Failure mode of reinforced concrete (RC) structures are classified according to tension reinforcement ratio of beam elements. To determine effect of tension reinforcement ratio on performance of RC structure, two planar RC structure were selected. One of them is 5 stories other of them is 7 stories. Two different concrete class, C20 and C25, were considered for analysis. Three tension reinforcement combinations were considered, three different tension reinforcement ratios were used. First case is the ratio of the tension reinforcement is lower than that of the compression reinforcement, second case is the ratio of the tension reinforcement is equal to the ratio of the compression reinforcement and third case is the ratio of the tensile reinforcement is higher than the compression reinforcement.

Corrosion effects on seismic capacity of reinforced concrete structures

2019 ◽  
Vol 37 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Antonio Bossio ◽  
Francesco Fabbrocino ◽  
Tullio Monetta ◽  
Gian Piero Lignola ◽  
Andrea Prota ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Seismic Behavior ◽  
Concrete Cover ◽  
Residual Service Life ◽  
Seismic Capacity ◽  
Rc Structures ◽  
Behavior Simulation ◽  
Cover Cracking ◽  
Rc Structure

AbstractRecently, corrosion prevention and monitoring of reinforced concrete (RC) structures became an important issue for seismic assessment of such kind of structures. Therefore, it is important to develop adequate models to represent material degradation into seismic behavior simulation of RC structures. Because of its effects, corrosion represents the most important form of degradation for materials and structures, both for wide diffusion and the amount of danger it presents. To understand the corrosion process is critical in order to design RC structures that are able to guarantee the required service life and in order to understand the residual service life and strength of an existing structure. The seismic behavior of a corroded framed RC structure is analyzed by means of push-over analyses, which allow understanding the development of the global behavior of the structure. Three different degrees of corrosion penetration were simulated, by means of the reduction of bars and stirrups’ diameters and concrete cover cracking and spalling, and three different configurations of corrosion, depending on the number of corroded frames and sides of the structural elements.

Experimental study on condition assessment of reinforced concrete structure using a dynamics response approach

2014 ◽  
Vol 32 (2) ◽  
pp. 89-101
Author(s):  
Chun Pong Sing ◽  
P.E.D. Love ◽  
P.R. Davis
Keyword(s):  
Reinforced Concrete ◽  
Natural Frequency ◽  
Time Domain ◽  
Damping Ratio ◽  
Content Type ◽  
Rc Structures ◽  
Random Decrement ◽  
Rc Structure ◽  
Non Linear ◽  
Linear Damping

Purpose – Condition assessment on reinforced concrete (RC) structures is one of the critical issues as a result of structure degradation due to aging in many developed countries. The purpose of this paper is to examine the sensitivity and reliability of the conventional dynamic response approaches, which are currently applied in the RC structures. The key indicators include: natural frequency and damping ratio. To deal with the non-linear characteristics of RC, the concept of random decrement is applied to analyze time domain data and a non-linear damping curve could be constructed to reflect the condition of RC structure. Design/methodology/approach – A full-scale RC structure was tested under ambient vibration and the impact from a rubber hammer. Time history data were collected to analyze dynamics parameters such as natural frequency and damping ratio. Findings – The research demonstrated that the measured natural frequency is not a good indicator for integrity assessment. Similarly, it was revealed that the traditional theory of viscous damping performed poorly for the RC with non-linear characteristics. To address this problem, a non-linear curve is constructed using random decrement and it can be used to retrieve the condition of the RC structure in a scientific manner. Originality/value – The time domain analysis using random decrement can be used to construct a non-linear damping curve. The results from this study revealed that the damage of structure can be reflected from the changes in the damping curves. The non-linear damping curve is a powerful tool for assessing the health condition of RC structures in terms of sensitivity and reliability.

FACTORS AFFECTING SEISMIC BEHAVIOUR OF REINFORCED CONCRETE STRUCTURES AFTER FIRE EXPOSURE

2019 ◽  
Vol 1 (Special Issue on First SACEE'19) ◽  
pp. 31-41 ◽  
Author(s):  
Alper Ilki ◽  
Ugur Demir
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Elevated Temperatures ◽  
Load Capacity ◽  
Lateral Load ◽  
Earthquake Risk ◽  
Fire Damage ◽  
Seismic Behaviour ◽  
Rc Structures ◽  
The Impact

In the areas under high earthquake risk, the impact of fire damage on the seismic performance of the reinforced concrete (RC) structures ought to be realistically taken into account while assessing the fire damage to develop reuse/repair/replace strategies through the remaining service life. In the scope of this study, a literature review is conducted on the changes of mechanical characteristics of concrete and reinforcement caused by a fire with a particular emphasis on the post-cooling stage. Post-cooling behaviour of RC members is different than the behaviour under elevated temperatures and hence it is of vital importance on structural seismic performance assessment after a fire. Apart from material-wise assessment methodologies, post-fire seismic performance of RC structural members is also discussed through post-fire simulated seismic loading tests conducted on full-scale cast-in-place and precast columns. The test results pointed out to a reduction in lateral load bearing capacity of the cast-in-place columns subjected to fire whereas fire-exposed precast columns demonstrated better performance in terms of residual lateral load capacity due to the lower axial load and larger heights. All columns exhibited satisfactory performance in terms of ductility.

scholarly journals Forensic to the Reinforced Concrete (RC) Structures at Library

2020 ◽  
Vol 19 (1) ◽  
pp. 6-14
Author(s):  
Tang Hing Kwong ◽  
Rudy Tawie ◽  
Siti Rozana Romali
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Concrete Strength ◽  
Reinforced Concrete Beam ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structure ◽  
Rebound Hammer ◽  
Rc Structures ◽  
Three Samples ◽  
Eurocode 2

This Forensic project has been proposed to investigate the reinforced concrete structure defect at library. There were found 65 points cracks and 20 points spalling in library such as only at reinforced concrete beam and slab part in first floor. The total of cracks which crack width less than 0.25 mm is 63 points and the crack width between 0.25 mm to 5.00 mm is 2 points only. These cracks had categorized as fine cracks because the crack width not more than 5 mm. There was 21 samples Rebound Hammer test was random measured the existing concrete compressive strength of critical structures which six samples at beams, six samples at slabs, six samples at columns and three samples at staircase in library. The Rebound Hammer test shown that average mid-point strength at beam is 33 N/mm2, slab is 25 N/mm², column is 38 N/mm2 and staircase is 37 N/mm2 . Based on the Eurocode 2, the minimum grade concrete required is 25N/mm2 to do the design for reinforced concrete structures, which all the existing concrete strength were achieved the minimum concrete strength. Finally, the Orion software are used to analysis and determine the size of steel reinforcement, the design found the required bar size of steel reinforcement at the middle span or continuous support is 2T16 & 2T25 or 2T20 & 2T25 but the existing steel reinforcement is 2T12 and 2T20 which the existing steel reinforcement could not be sustained the big loading that applied on the library.

scholarly journals New design model of reinforced concrete beams in bending considering the ductility factor

2020 ◽  
Vol 13 (1) ◽  
pp. 120-141
Author(s):  
C. G. NOGUEIRA ◽  
I. D. RODRIGUES
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Input Parameter ◽  
Reinforced Concrete Beams ◽  
Design Model ◽  
Design Codes ◽  
Rc Structures ◽  
Ductility Factor ◽  
Eurocode 2 ◽  
Definition Of

Abstract Ductility is a recommended characteristic by different RC structures design codes around the world, such as ABNT NBR 6118 [2], ACI 318 [1] and EUROCODE 2 [4]. Despite the recommendation of ductility, the codes only define this criterion in a qualitative way, without quantification about how ductile the structure is, and not being able to stablish a ductility level in the design phase. In this context, this paper proposes a new design model of reinforced concrete beams in bending considering the explicit definition of the input parameter named ductility factor, which quantifies the structure’s ability to withstand displacement before it breaks.

scholarly journals Probabilistic Evaluation of Service Life for Reinforced Concrete Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sanjeev Kumar Verma ◽  
Sudhir Singh Bhadauria ◽  
Saleem Akhtar
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Probabilistic Models ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Rc Structures ◽  
Rc Structure ◽  
Probabilistic Evaluation

Degradation of performance and deterioration of different components of reinforced concrete (RC) structures increase with the age of structure. This deterioration of reinforced component depends on several parameters. However, modeling service life of RC structure by considering all the parameters is a difficult job, as most of the parameters are uncertain in nature. Probabilistic models account well for the uncertainties in the parameters responsible for deterioration of RC structures. This paper presents a review of several recent service life models developed using probability based concepts.

Optimum Design of Reinforced Concrete Beams

2020 ◽  
pp. 71-91
Keyword(s):  
Reinforced Concrete ◽  
Optimum Design ◽  
Nonlinear Behavior ◽  
Optimization Method ◽  
Reinforced Concrete Beams ◽  
Metaheuristic Algorithms ◽  
Rc Beam ◽  
Rc Structures ◽  
Eurocode 2 ◽  
The Cost

The design of reinforced concrete (RC) beams need special conditions to provide a ductile design. In this design, the maximum amount of tensile reinforcement must be limited to singly reinforced design. After the singly reinforced limit, the cost of doubly reinforced RC beam rapidly increases, and it may not be an optimum design. To consider this nonlinear behavior and other rules used in RC structures according to regulations such as ACI 318: Building code requirements for structural concrete and Eurocode 2: Design of concrete structures, an algorithmic and iteration optimization method is needed. In this chapter, two examples are presented, and optimum results are shared for methodologies employing several metaheuristic algorithms. The importance of using metaheuristic algorithms can be seen in this chapter.

Numerical investigation on damage performance of a reinforced concrete structure subjected to machine loads

2020 ◽  
Vol 6 (3) ◽  
pp. 132
Author(s):  
Memduh Karalar ◽  
Murat Çavuşli
Keyword(s):  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Structural Engineering ◽  
3D Model ◽  
Three Dimensional ◽  
Reinforced Concrete Structure ◽  
Rc Structures ◽  
Machine Element ◽  
Rc Structure ◽  
Capacity Performance

Investigation of carrying capacity performance of reinforced concrete (RC) structures is very important for structural engineering. In this study, it is aimed to examine the nonlinear carrying capacity performance of an RC laboratory structure by using three dimensional (3D) modelling approach. For this purpose, Zonguldak Bulent Ecevit University Laboratory Structure is selected and it is modeled as three dimensional by utilizing IDECAD static software. After modelling all beams, columns and floors according to 2018 Turkish earthquake code, concrete classes are determined for all bearing elements and specified concrete classes are defined for all elements of 3D model. Then, structure is analyzed for empty situation (Case 1) and structural performance of building is analyzed to this situation. In the past, a flat of this RC structure has been exposed to strong machine loads. For this reason, a machine which is fixed on the floor is placed in the 3D model and RC structure is analyzed considering nonstructural machine element loads (Case 2). According to analysis results, Case 1 is compared with Case 2 and it is clearly seen that nonstructural machine loads effect nonlinear carrying capacity performance of RC buildings.

scholarly journals Durable Steel-Reinforced Concrete Structures for Marine Environments

2021 ◽  
Vol 13 (24) ◽  
pp. 13695
Author(s):  
Robert E. Melchers ◽  
Igor A. Chaves
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Localized Corrosion ◽  
Marine Environments ◽  
Reinforcement Corrosion ◽  
Rc Structures ◽  
Air Voids ◽  
Rc Structure ◽  
Alkali Aggregate Reactivity

Even in harsh marine environments, concrete structures reinforced with steel can show excellent long-term durability, with little or no reinforcement corrosion. Very few actual reinforced concrete (RC) structures have been closely scrutinized over many years and subject to interpretation using recent state-of-the-art understanding gained from detailed laboratory observations. Such a case is described for an 80-year-old RC structure observed annually over about 30 years in what is essentially an extraordinary long experiment. Despite very high chloride concentrations, field excavation evidence showed that reinforcement corrosion overall remains minimal, except where insufficient concrete compaction permitted air-voids to initiate quite severe, very localized corrosion even with still high concrete pH. It is possible that the use of blast furnace slag as aggregate may have assisted the observed durability. The case study supports other studies that show that it is possible to achieve long-term durable and therefore sustainable RC structures without additives and using only conventional reinforcement steels and conventional cements and aggregates. However, the potential dangers of deep narrow cracking extending to the reinforcement and the potentially deleterious effects of alkali–aggregate reactivity of some aggregates needs to be considered.

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