scholarly journals Numerical and Experimental Study on Deficient Short Steel Tubes Strengthened with CFRP Under Compression

2019 ◽  
Author(s):  
Mohammad Reza Ghaemdoust ◽  
Omid Yousefi ◽  
Kambiz Narmashiri ◽  
Masoumeh Karimian
Keyword(s):  
Bearing Capacity ◽  
Numerical Study ◽  
Three Dimensional ◽  
Local Buckling ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Steel Columns ◽  
Repair Costs ◽  
The Impact

In view of development and repair costs, support of structures is imperative. Several factors, for example, design and calculation errors, absence of appropriate installation, change of structures application, exhaustion, seismic tremor, fire and natural conditions diminish their strength. In such cases, structures have need of rehabilitation and restoration to achieve their original performance. One of the most up to date materials for retrofitting is carbon fiber reinforced polymer (CFRP) that can provide an amount of restriction to postpone buckling of thin steel walls. This paper provides a numerical and experimental investigation on CFRP strengthened short steel tubes with initial horizontal and vertical deficiency under compression. Ten square and circular specimens were tested to study effects of the following parameters: (1) position of deficiency, horizontal or vertical; (2) tube shape, square or circular; (3) CFRP strengthening. In the experiments, axial static loading was gradually applied and for the numerical study three-dimensional (3D) static nonlinear analysis method using ABAQUS software was performed. The results show that deficiency reduces load-bearing capacity of steel columns and the impact of horizontal deficiency is higher than the impact of vertical deficiency, in both square and circular tubes. Use of CFRP materials for strengthening of short steel columns with initial deficiency indicates that fibers play a considerable role on increasing load bearing capacity, reducing stress at the damage location, preventing deformation caused by deficiency and delaying local buckling. Both numerical and experimental outcomes are in good agreement, which underlines the accuracy of the models adopted.

scholarly journals BUCKLING OF SLENDER COMPOSITE CONCRETE‐FILLED STEEL COLUMNS

2010 ◽  
Vol 16 (2) ◽  
pp. 230-236 ◽  
Author(s):  
C. Douglas Goode ◽  
Artiomas Kuranovas ◽  
Audronis Kazimieras Kvedaras
Keyword(s):  
Bearing Capacity ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Hollow Section ◽  
Steel Columns ◽  
Tubular Columns ◽  
Cylinder Strength ◽  
Experimental Values ◽  
Concrete Filled Steel Tubes

The paper presents the analysis of the experimental data of 1817 on concrete‐filled steel tubes ‐ CFSTs. These results are compared with the predicted results of the load‐bearing capacity of calculations of slender elements according to the methods suggested by Eurocode 4. The following types of tested CFSTs were analysed: circular and rectangular hollow section stub and long columns fully filled with concrete, which were with or without applied moments at the ends of specimen. During the results obtained in the result of the tests on the load bearing capacity for circular concrete‐filled steel tubular columns correspond with the calculated values based on methods presented by Eurocode 4. The experimental values of load bearing capacity for members of concrete‐filled rectangular hollow sections agree very well with the theoretical values where the concrete cylinder strength is below 75 N/mm2. The analysis demonstrated that preloading of concrete‐filled hollow section members does not influence the load bearing capacity. This paper also presents the examination of stress state distribution for concrete‐filled hollow section members, influence of concrete preloading and of longitudinal stress strain curves. Santrauka Straipsnyje aptariami 1817 betonšerdžiu plieniniu vamzdiniu strypu eksperimentiniai duomenys. Šie duomenys lyginami su rezultatais, gautais remiantis Eurocode 4 pateiktais kompozitiniu elementu laikomosios galios nustatymo metodais. Analizuojami tokie betonšerdžiu plieniniu strypu bandiniu tipai: pilnavidures trumpos arba liaunos apskritojo ir stačiakampio skerspjūvio vamzdines betonšerdes plienines kolonos su ju galuose veikiančiu lenkiamuoju momentu arba be jo. Apskritojo skerspjūvio betonšerdžiu kolonu bandymu metu gautieji laikomosios galios rezultatai atitinka remiantis Eurocode 4 pateiktais metodais apskaičiuotasias ju reikšmes. Stačiakampio skerspjūvio betonšerdžiu elementu laikomosios galios bandymais rastosios reikšmes labai gerai atitinka teorines reikšmes, kai šerdies betono ritininis stipris nesiekia 75 N/mm2. Analizuojant nustatyta, kad išankstinis betonšerdžiu elementu apkrovimas neturi beveik jokio poveikio elementu laikomajai galiai. Šiame straipsnyje taip pat nagrinejamas betonšerdžiu elementu itempiu būviu pasiskirstymas, betono apspaudimo poveikis bei išilginiu deformaciju ir itempiu kreives.

scholarly journals Fire Performance of Columns Made of Normal and High Strength Concrete: A Comparative Analysis

2016 ◽  
Vol 711 ◽  
pp. 564-571 ◽  
Author(s):  
Thomas Gernay
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Strength Loss ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Strength Concrete ◽  
The Impact

The use of high strength concrete (HSC) in multi-story buildings has become increasingly popular. Selection of HSC over normal strength concrete (NSC) allows for reducing the dimensions of the columns sections. However, this reduction has consequences on the structural performance in case of fire, as smaller cross sections lead to faster temperature increase in the section core. Besides, HSC experiences higher rates of strength loss with temperature and a higher susceptibility to spalling than NSC. The fire performance of a column can thus be affected by selecting HSC over NSC. This research performs a comparison of the fire performance of HSC and NSC columns, based on numerical simulations by finite element method. The thermal and structural analyses of the columns are conducted with the software SAFIR®. The variation of concrete strength with temperature for the different concrete classes is adopted from Eurocode. Different configurations are compared, including columns with the same load bearing capacity and columns with the same cross section. The relative loss of load bearing capacity during the fire is found to be more pronounced for HSC columns than for NSC columns. The impact on fire resistance rating is discussed. These results suggest that consideration of fire loading limits the opportunities for use of HSC, especially when the objective is to reduce the dimensions of the columns sections.

An Evaluation of Prestressed Stayed Steel Columns Load Bearing Capacity with Bayesian Neural Networks

2010 ◽  
Author(s):  
Araujo R. R. ◽  
Vellasco P. C. G. S. ◽  
Vellasco M. M. B. R. ◽  
Andrade S. A. L. ◽  
Lima L. R. O. ◽  
...  
Keyword(s):  
Neural Networks ◽  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Bayesian Neural Networks ◽  
Steel Columns

scholarly journals An Analytical Investigation of Modular Concrete-filled Square Steel Tubes based on the Strain Compatibility

2015 ◽  
pp. 424-431
Author(s):  
Seon-Chee Park ◽  
Won-Kee Hong ◽  
Hyo-Jin Ko
Keyword(s):  
Bearing Capacity ◽  
Analytical Methods ◽  
Design Method ◽  
Analytical Investigation ◽  
Design Codes ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Composite Tubes ◽  
Load Bearing ◽  
Strain Compatibility

Concrete-filled square steel tubes demonstrating good structural resistance against vertical and lateral loads can be used for modular constructions. To promote the applications of the composite tubes to modular construction, it is important to provide simple but accurate analytical methods that can elucidate the structural behaviour of the composite tubes. A number of international design codes are known to calculate the flexural load bearing capacity of the concrete-filled square steel tubes. Some, however, are not predicting the behaviour of the composite tubes accurately. An analytical investigation of concrete-filled square steel tubes was presented in this paper. A strain compatibility based design method considering confinement effect of concrete in tubes was proposed to estimate the flexural strength of composite steel tube filled with concrete. Nominal moment capacities estimated in accordance with the standards of AIJ(Japan), AISC(USA), Eurocode4(Europe) and KSSC(Korea) were compared with the analytical value obtained using the strain compatibility based design method. Since the design method with strain compatibility proposed in the study reflects the concrete confinement with accurate estimation of the neutral axis of composite tube section, the flexural moment capacity of composite tube section can be accurately obtained. The test results of other researchers including Lu and Kennedy were used to verify the reliability of the proposed design method. These experimental results were shown to be the best correlated with the analytical results provided by the proposed method in this paper than any other analytical methods proposed by the international codes that were used to calculate flexural load bearing capacity. The 6% of errors were demonstrated by the proposed approach while bigger errors were observed in the analytical calculations of other design codes as large as 17%.

scholarly journals Finite Element Analysis of Load Bearing Capacity of a Reinforced Concrete Frame Subjected to Cyclic Loading

2016 ◽  
Vol 2 (5) ◽  
pp. 221-225 ◽  
Author(s):  
Mahdi Bamdad ◽  
Abdolreza Sarvghad Moghadam ◽  
Mohammad Javad Mehrani
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Impact Behavior ◽  
Reinforced Concrete Frame ◽  
Load Bearing Capacity ◽  
Element Analysis ◽  
Load Bearing ◽  
Concrete Frame ◽  
The Impact ◽  
Abaqus Software

Many methods have been developed in order to study the impact behavior of solids and structures. Two common methods are finite element and experimental method. The nonlinear finite element method is one the most effective methods of predicting the behavior of RC beams from zero-load to failure and its fracture, yield and ultimate strengths. The advantage of this method is its ability to make this prediction for all sections of the assessed RC beam and all stages of loading. This paper compares the experimental results obtained for a RC frame with the numerical results calculated by ABAQUS software, and plots both sets of results as hysteresis–displacement diagrams. This comparison shows that the numerical FEM implemented via ABAQUS software produce valid and reliable results for load bearing capacity of RC frames subjected to cyclic loads, and therefore has significant cost and time efficiency advantages over the alternative approach

scholarly journals Impact of the fire on the bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi. History and architecture

Vestnik MGSU ◽  
2021 ◽  
pp. 1567-1572
Author(s):  
Emmanuel Mikerego ◽  
Donatien Nduwimana
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Negative Impact ◽  
Heating Temperature ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Ordinary Concrete ◽  
The Impact

Introduction. This paper presents the results of an assessment of the impact of fire on the bearing capacity of the ordinary concrete, to be taken into account in the rehabilitation of fire-damaged reinforced concrete structures in Burundi. Materials and methods. Experimental samples of the ordinary concrete made respectively of coarse river aggregates and crushed coarse quarry aggregates were prepared and subjected to different heating temperatures (250, 350, 450, 600 and 900 °C) simulating the fire. After natural cooling, experimental samples were subjected to compression test; and diagrams showing the loss of the load-bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi were drawn. Results. Negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concrete made of crushed coarse quarry aggregates loses 50 and 78 % of its bearing capacity at around 525 and 900 °C of heating temperature, respectively. Similarly, concrete made of coarse river aggregates loses 50 and 70 % of its load-bearing capacity respectively at 600 and 900 °C of heating temperature. An evaluation curve of the after-fire bea­ring capacity of the concrete used in reinforced concrete structures in Burundi is established. Conclusions. The negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concretes made of crushed coarse quarry aggregates and concrete made of coarse river aggregates lose 50 % of its bearing capacity at around 525 and 600 °C of heating temperature respectively. Knowing the heating temperature that the fire-damaged reinforced concrete structure has undergone is indispensable in deciding on its demolition or rehabilitation.

scholarly journals Failure Assessment of Embankment Dam Elements: Case Study of the Pirot Reservoir System

2022 ◽  
Vol 12 (2) ◽  
pp. 558
Author(s):  
Dragan Rakić ◽  
Milan Stojković ◽  
Damjan Ivetić ◽  
Miroslav Živković ◽  
Nikola Milivojević
Keyword(s):  
Bearing Capacity ◽  
Grout Curtain ◽  
Strength Analysis ◽  
Embankment Dam ◽  
Load Bearing Capacity ◽  
Element Analysis ◽  
Load Bearing ◽  
Reservoir System ◽  
The Impact

The paper presents a functionality investigation of the key dam elements based on finite element analysis. A detailed analysis of filtration processes, dam strength, and the surrounding rock mass was conducted. Dam elements whose potential damage could jeopardize the normal functioning of the embankment dam have been identified. A particular emphasis was placed on the analysis of dam elements that have been identified as weak points. A numerical analysis of the impact of individual grout curtain zone failure on leakage under the dam body, a strength analysis of the overflow section, as well as the analysis of the slope stability that can compromise the functioning of the spillway have been performed. To analyze the partial stability of individual structural elements, a new measure of local stability was introduced as the remaining load-bearing capacity. As a case study, the Zavoj dam, which is a part of the Pirot reservoir system in the Republic of Serbia, was used. Investigation revealed that local damage to the grout curtain will not significantly increase leakage under the dam body, the overflow section is one of the most robust elements of the dam, but the slope above the spillway can compromise the functioning of the overflow and thus the safety of the entire dam. Based on the analysis of the results of the remaining load-bearing capacity, the dependence of the spillway capacity on earthquake intensity has been defined. The established relationship represents a surrogate model for further assessment of dynamic resilience of the complex multipurpose reservoir system, within the scope of the advanced reservoir system management.

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