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1
Content available Strength analysis of eccentrically loaded thin-walled steel lipped C-profile columns
Czechowski Leszek, Kotełko Maria, Jankowski Jacek, Ungureanu Viorel, Sanduly Annabella
Archives of Civil Engineering
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2023
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Vol. 69, nr 3
301--316
EN
The work includes the results of numerical, analytical-numerical and experimental study into the influence of load eccentricities with regard to major axis on post-buckling behaviour and load-carrying capacity of thin-walled cold-formed steel lipped channel section columns. The study was solved by using the finite element method (code Ansys) with taking into consideration a full material characteristics in logarithmic strain system and geometric nonlinearities. The analytical-numerical solution was based on Koiter’s theory with an application of finite difference method (FDM). Some chosen results of numerical simulations have been compared to experimental results. The deformations of columns were registered by means of Digital Image Correlation Aramis System (DICAS) to observe the maps and the magnitude of displacements for adequate point of a load. The analyses showed that the decrease in maximum load in a dependency on the eccentricity value can be even 3 times minor in a comparison to the load-carrying capacity of axially loaded column.
PL
Praca dotyczy analiz numerycznych, numeryczno-analitycznych i eksperymentalnych wpływu obciążeń mimośrodowych względem osi centralnej Imax na pokrytyczne zachowanie i nośność cienkościennych zimno formowanych stalowych słupów o przekroju otwartym z żebrami końcowymi w pasach. Problem został rozwiązany stosując metodę elementów skończonych (program Ansys) z uwzględnieniem pełnych charakterystyk materiałowych w układnie logarytmicznym oraz nieliniowości geometrycznych. Rozwiązanie analityczno-numeryczne zostało oparte o teorię Koitera z zastosowaniem metody różnic skończonych. Wybrane wyniki symulacji zostały porównane z wynikami empirycznymi. Deformacje słupów podczas wykonywania badań doświadczalnych były rejestrowane optyczną metodą cyfrowej korelacji obrazów za pomocą systemu Aramis w celu określenia map deformacji i wielkości przemieszczeń punktów dla określonego obciążenia. Wyniki analizy pokazały, iż spadek w maksymalnych siłach w zależności od przesunięcia siły ściskającej względem osi centralnej słupa, może być nawet trzykrotny w odniesieniu do nośności ceowników ściskanych osiowo.
2
Content available Bearing capacity of eccentrically loaded strip footing on spatially variable cohesive soil
Dobrzański Jędrzej, Kawa Marek
Studia Geotechnica et Mechanica
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2021
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Vol. 43, nr 4
425--437
EN
The study considers the bearing capacity of eccentrically loaded strip footing on spatially variable, purely cohesive soil. The problem is solved using the random finite element method. The anisotropic random field of cohesion is generated using the Fourier series method, and individual problems within performed Monte Carlo simulations (MCSs) are solved using the Abaqus finite element code. The analysis includes eight different variants of the fluctuation scales and six values of load eccentricity. For each of these 48 cases, 1000 MCSs are performed and the probabilistic characteristics of the obtained values are calculated. The results of the analysis indicate that the mean value of the bearing capacity decreases linearly with eccentricity, which is consistent with Meyerhof's theory. However, the decrease in standard deviation and increase in the coefficient of variation of the bearing capacity observed are non-linear, which is particularly evident for small eccentricities. For one chosen variant of fluctuation scales, a reliability analysis investigating the influence of eccentricity on reliability index is performed. The results of the analysis conducted show that the value of the reliability index can be significantly influenced even by small eccentricities. This indicates the need to consider at least random eccentricities in future studies regarding probabilistic modelling of foundation bearing capacity.
3
Content available Strengthening of bi-axially loaded RC slab-column connection using steel plates and stiffeners
Neamah Zainab A., Al-Ramahee Munaf A.
Przegląd Naukowy Inżynieria i Kształtowanie Środowiska
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2021
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Vol. 30, No. 1
29--37
EN
This paper presented a strengthening technique for enhancement reinforced concrete (RC) slab-column connection behavior using steel plates and steel stiffeners. A bi-axial load was applied with an eccentricity of 150 mm in both x and z directions. Four specimens with dimensions of 1,600 × 1,600 × 100 mm were tested in this research. The steel plate dimensions were chosen to be 600 × 600 and 800 × 800 mm with 6 mm thickness. The steel stiffeners are used to support and enhance the steel plate that it is extended from column to the slab-column connection with different dimension. The results showed an improvement in the stiffness of slab and increasing in the ultimate capacity. Also, when the steel plates dimensions increased, the ultimate capacity and stiffness increased.
4
Content available remote Performance of circular bimetallic tube confined concrete slender columns under eccentric compression
Gao Shan, Guo Lanhui
Archives of Civil and Mechanical Engineering
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2021
|
Vol. 21, no. 2
13--39
EN
This paper aims to investigate the performance of thin-walled circular stainless steel-carbon steel bimetallic tube confined concrete slender columns under eccentric compression. 14 slender columns including bimetallic tube confined concrete (BTCC) with and without rebar, and concrete-filled bimetallic tube (CFBT) were tested. A parametric analysis is conducted based on the validated finite-element model. The results show that the two steel tube layers worked well together and the thin-walled BTCC specimens behaved in a ductile manner. Under the same parameters, the decrease of the diameter–thickness ratio of bimetallic tube improves the bearing capacity and rigidity of the BTCC slender column, but reduces its ductility in the descending stage. The confinement effect of bimetallic tube on the concrete in BTCC columns is stronger than that in CFBT columns. When the yield strength of stainless steel and carbon steel is similar, the stainless steel–total steel ratio has little effect on the capacity of the column. Provided meeting the requirements of corrosion resistance, relatively thinner stainless steel tube is preferred to reduce the cost. The comparison between the simulation and the calculation results shows that the current design method can predict the bearing capacity of the BTCC slender column with large diameter–thickness ratio.
5
Content available Experimental bearing capacity of eccentrically loaded foundation near a slope
Mansouri Tarek, Abbeche Khelifa
Studia Geotechnica et Mechanica
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2019
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Vol. 41, nr 1
33-41
EN
Based on the response of small-scale model square footing, the present paper shows the results of an experimental bearing capacity of eccentrically loaded square footing, near a slope sand bed. To reach this aim, a steel model square footing of (150 mm × 150 mm) and a varied sand relative density of 30%, 50% and 70% are used. The bearing capacity-settlement relationship of footing located at the edge of a slope and the effect of various parameters such as eccentricity (e) and dimensions report (b/B) were studied. Test results indicate that ultimate bearing capacity decreases with increasing load eccentricity to the core boundary of footing and that as far as the footing is distant from the crest, the bearing capacity increases. Furthermore, the results also prove that there is a clear proportional relation between relative densities –bearing capacity. The model test provides qualitative information on parameters influencing the bearing capacity of square footing. These tests can be used to check the bearing capacity estimated by the conventional methods.
6
Content available remote Numerical and experimental analysis of stability of thin-walled composite structures subjected to eccentric load
Debski Hubert
Archives of Civil and Mechanical Engineering
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2019
|
Vol. 19, no. 3
792--802
EN
The study investigates the effect of eccentric load on the stability and post-critical states of thin-walled composite top-hat cross-section columns made of CFRP under compression. The specimens were subjected to compressive load on the universal testing machine Zwick Z100 with regard to both axial and eccentric compressive loads. On the basis of the experimental studies, numerical models of thin-walled composite profiles were designed and verified by numerical analysis based on the FEM. The first stage of the conducted studies was performing a linear buckling analysis of stability of composite structures. The second stage of the analysis involved performing a nonlinear analysis of the thin-walled structures with geometric imperfections reflecting the lowest buckling modes. The obtained test results showed various effects of non-axial compressive load on the critical load values and stiffness of the con- struction in the post-critical state. In the case of eccentric loading in the direction parallel to the web of the top-hat profiles, the critical load values practically did not change – a drop in the force did not exceed 1.5%, as well as there was no change in the stiffness of the structure in the post-critical state. The realization of the eccentricity in the direction perpendicular to the profile web caused a drop in the critical force equal 43% and a significant decrease in the stiffness of the structure. On the other hand, implementation of the eccentricity load toward the web caused an increase in the critical force by more than 20%, despite very small eccentricity values of only 4 mm were applied. This proved high sensitivity of the tested structures to the non-axial load in the direction perpendicular to the web of the profile. The FEM results and the experimental findings showed satisfactory agreement.
7
Content available remote Novel shearhead reinforcement for slab-column connections subject to eccentric load and fire
Al-Hamd Rwayda Kh. S., Gillie Martin, Cunningham Lee S., Warren Holly, Albostami Asad S.
Archives of Civil and Mechanical Engineering
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2019
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Vol. 19, no. 2
503--524
EN
Traditional means of reinforcing concrete flat slab-column connections against punching shear, such as increasing slab thickness, or provision of shear links, all have drawbacks. This paper proposes a novel type of punching shear reinforcement in the form of a shearhead to enhance connection strength and ductility. The structural behaviour of the connection is explored experimentally by testing nine specimens under various loading conditions including eccentric loads that produce combined axial and bending effects. Specimens with and without shearheads are compared. This is followed by a detailed numerical investigation using finite element analysis to obtain more in-depth insights into the connection behaviour when shearheads are present. The performance of the proposed system is also investigated under fire conditions for the first time. It is found that the proposed shearheads improve the performance of slab-column connections in all conditions and particularly under concentric loading and in fire conditions.
8
Content available remote Przybliżona metoda wymiarowania mimośrodowo ściskanych przekrojów kołowych
Pędziwiatr J.
Materiały Budowlane
|
2016
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nr 9
52--53
PL
Artykuł opisuje dokładny oraz przybliżony sposób wyznaczania sił wewnętrznych w mimośrodowo ściskanym kołowym przekroju żelbetowym. Przybliżony sposób rozwiązania polega na zastosowaniu linearyzacji do zależności pomiędzy wartością odkształcenia w betonie a wartościami sił wewnętrznych. Metoda przybliżona pozwala łatwo wyznaczać zbrojenie takiego przekroju. Dokładność metody w przypadku praktycznego zastosowania jest dobra. Umożliwia to wykorzystanie jej przez projektantów.
EN
The article describes both strict and approximate methods for dimensioning of circular cross-section under eccentric full compression. The approximate way is based on linearizing of dependence between concrete strain and internal forces. The approximate method allows quite easy to establish reinforcement. For the practice, the accuracy is good enough. It allows to use the presented method by common designers.
9
Content available remote Behavior of eccentrically loaded rcc columns confined with frp sheets
Chakrabarti A., Bhargava P.
International Journal of Applied Mechanics and Engineering
|
2011
|
Vol. 16, no 4
943-958
EN
A nonlinear finite element model is developed for the analysis of an RCC (reinforced concrete column) confined by FRP (fiber - reinforced polymers) sheets and subjected to eccentric loading. A practical design of FRP confined concrete columns requires an accurate estimate of the performance enhancement due to the confinement mechanism under eccentric loading. Therefore, a confinement model is developed which relates the confined concrete strength with the unconfined concrete strength. In the present study, a 3-D finite element model is developed using the finite element software, ANSYS for the analysis of an FRP confined reinforced concrete circular column under axial and eccentric loading. The effects of four important parameters are studied in the present work: namely, the unconfined concrete strength, FRP thickness with different layer orientation, orthotropic properties of FRP and orientation of FRP fibers. The study focused on some interesting effects of these parameters on the confinement effectiveness of eccentrically loaded reinforced concrete columns. Many new results are generated which should be useful for future references.
10
Badania eksperymentalne mimośrodowo obciążonych złącz płyta-słup zbrojonych poprzecznie
Sitnicki M.
Budownictwo Ogólne i Konstrukcje Drewniane : zeszyt naukowy
|
2007
|
Nr 8
59--68
PL
Artykuł przedstawia wyniki badań mimośrodowo obciążonych złączy płyty i słupa, zbrojonych na ścianie trzpieniami dwugłówkowymi. Opisana zaobserwowaną podczas badań interakcję zbrojenia poprzecznego i betonu złącza w przenoszeniu siły ścinającej oraz zmianę odkształceń dolnej powierzchni betonu sygnalizującą moment utraty nośności. Rezultaty badań będą służyły opracowaniu modelu obliczeniowego, określającego nośność na przebicie mimośrodowo obciążonych, poprzecznie zbrojonych złączy płyta-słup.
EN
The paper describes experimental study of eccentric loaded slab column connections strengthened with double headed studs shear reinforcement. The interaction of shear reinforcement and concrete was observed. Near ultimate limit state shear reinforcement carried about 45% of failure load. Failure process was preceded by extreme of radial strains measured on the slab surface, near the column. Results of experiments are going to make calculation model of slab-column connections punching capacity.
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