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1

Nonlinear finite element analysis of double skin composite columns subjected to axial loading

Ipek Süleyman, Güneyis Esra Mete

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

109--133

EN

The study aimed to simulate the behavior of the concrete-filled double skin steel tubular (CFDST) composite columns having a circular hollow section using the finite element method (FEM). To indicate the accuracy and the reliability of the model, the proposed FEM model was verified by the experimental test results available in the literature. Moreover, the code-based formulas (ACI, AISC, and Eurocode 4) and some empirical models suggested by the previous researchers for predicting the axial capacity of CFDST columns were used in this study to compare their results with the proposed FEM model. Furthermore, to visualize the effectiveness of sectional properties and infilled concrete compressive strength on the ultimate axial strength of double skin composite columns, a parametric study was conducted. For this, 72 test specimens were modeled considering two outer and inner steel tube diameters, three outer and inner steel tube thicknesses, and two different concrete cylinder strengths. All results were statistically evaluated. It was observed that the proposed FEM model had a good prediction performance. As well, the FEM model results indicated that the sectional properties, in particular, the diameter of the outer steel tube and concrete compressive strength, had remarkable effects on the load-carrying capacity of CFDST columns.

2

Comparison of optimal costs of axially loaded RC tension members using Indian and Euro standards

Karthiga Shenbagam N., Arunachalam N.

Archives of Civil Engineering

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2017

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Vol. 63, nr 1

99--113

EN

The aim of this study is to find the cost design of RC tension with varying conditions using the Artificial Neural Network. Design constraints were used to cover all reliable design parameters, such as limiting cross sectional dimensions and; their reinforcement ratio and even the beahviour of optimally designed sections. The design of the RC tension members were made using Indian and European standard specifications which were discussed. The designed tension members according to both codes satisfy the strength and serviceability criteria. While no literature is available on the optimal design of RC tension members, the cross-sectional dimensions of the tension membersfor different grades of concrete and steel, and area of formwork are considered as the variables in the present optimum design model. A design example is explained and the results are presented. It is concluded that the proposed optimum design model yields rational, reliable, and practical designs.

PL

Niniejsza praca została poświęcona optymalnemu projektowi zbrojonych cięgien. Zaprojektowano blisko pięćset zbrojonych cięgien zgodnie ze standardem indyjskim IS 456:2000 i standardem europejskim EN1992, ręcznie przy użyciu arkuszy kalkulacyjnych Microsoft Excel. Uwzględnione zmienne stanowią charakterystyczną wytrzymałość betonu, wahającą się od 25 do 50N/mm2 dla obu specyfikacji kodału? (codal?). Wytrzymałość plastyczna stali waha się pomiędzy 250, 415, 500 i 550 N/mm2 w przypadku IS 456:2000 i pomiędzy 235, 275, 355, 420 i 460 N/mm2 w przypadku standardu europejskiego. Obciążenie osiowe wahało się od 500kN do 3000 kN. Teoretyczne wyniki uzyskane na podstawie ręcznego projektu zostały wyjaśnione poniżej.

3

An experimentally validated model for the ilizarov fixator considering the loss of wire’s pretension

Kourkoulis S. K., Mitousoudis A.

Engineering Transactions

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2016

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Vol. 64, iss. 4

621--627

EN

The purpose of this study is to assess the biomechanical performance of the Ilizarov fixator and to attempt optimization of its configuration. Attention is focused to the quantification of the wires’ pretension loss. The study is implemented according to a combined experimental and numerical scheme: The data of a long series of experiments are used to calibrate and validate a numerical model. The model is then used for parametric analysis of the factors which, according to clinical experience, influence the efficiency of the device. It was concluded that the most critical factors are the pretension of the wires, the angle between them and the rings’ diameter; the role of the remaining factors is of rather minor importance.

4

Soft methods in the prediction and identification analysis of axially compressed R/C columns

Ziaja D., Waszczyszyn Z.

Computer Assisted Methods in Engineering and Science

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2014

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Vol. 21, no. 1

59--66

EN

Two problems are presented in the paper concerning axial loading of R/C columns: I) prediction of critical loads, II) identification of concrete strength. The problems were analyzed by two methods: A) Gaussian Processes Method, B) Advanced Back-Propagation Neural Network. The results of the numerical analysis are discussed with respect to numerical efficiency of the applied methods.

5

Poślizg niskociśnieniowych pali iniekcyjnych w gruncie w warunkach obciążenia osiowego

Pachla H.

Geoinżynieria : drogi, mosty, tunele

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2013

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nr 2

58-61

EN

Low-pressure injection piles are increasingly used both while reinforcing old foundations and designing new engineering solutions. In the course of design works, piles are often linked functionally with foundations. The research presented in this study does not confirm the guidelines according to which the coefficients reducing the bearing capacity of piles used as part of a set of piles should be applied. The area around a pile, which is affected by significant ground deformation, is very limited. According to the performed experiments, piles bear different in fluence on cohesive and non-cohesive soils. In both cases, a noticeable difference of pile and ground dislocation within their contact zone has occurred. It therefore seems necessary to verify the operating model of a pile in the ground, considering the slipping of both means in relation to each other.

6

Niskociśnieniowe pale iniekcyjne wyciągane z gruntu

Pachla H.

Geoinżynieria : drogi, mosty, tunele

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2013

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nr 3

30-33

PL

Niskociśnieniowe pale iniekcyjne znajdują szerokie zastosowanie w wielu konstrukcjach inżynierskich, w przypadkach gdy decydujące o stabilności konstrukcji jest jej zakotwienie w gruncie. Podczas projektowania istotne znaczenie ma poprawność modelu współpracy pala z otaczającym go gruntem w warunkach obciążenia, powodującego podnoszenie (wyciąganie) pala. W niniejszym tekście podjęto próbę doświadczalnej weryfikacji przemieszczeń niskociśnieniowych pali iniekcyjnych w warunkach podnoszącego pal obciążenia osiowego ze swobodną powierzchnią gruntu.

EN

Low-pressure injection piles are widely used in many engineering structures, where ground anchoring is of decisive importance. In the course of design it is important to ensure the correctness of the pile cooperation model with the surrounding ground in the situation of lifting pressure (pile pushing). In this text, it was attempted to experimentally verify the movement of low-pressure injection piles in the conditions of lifting axial forces and loose ground surface.

7

Przemieszczenia pali iniekcyjnych w warunkach obciążenia osiowego

Pachla H.

Geoinżynieria : drogi, mosty, tunele

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2012

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nr 3

30-32

EN

The results of relocation measurements carried out for injection piles under axial load in wide range of loads, considerably exceeding their normative carrying capacity, indicate that employed computational models do not represent actual deformation process in an appropriate way. Taking into account slide at the contact between pile side surface and soil makes it possible to approximate theoretical model behaviour to actual soil reaction. Moreover, the proposed model gives an opportunity to characterise many effects resulting from susceptible combination of two different materials - cement grout and soil. In particular when we abandon the assumption made in this work of the interaction between soil and pile deformation.

8

Pale iniekcyjne w warunkach obciążenia osiowego : weryfikacja doświadczeń

Pachla H.

Geoinżynieria : drogi, mosty, tunele

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2012

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nr 1

26-30

EN

Injection piles, widely used in strengthening of existing foundations, have little experimental basis to verify their design assumptions. Relationships assumed on the basis of research on concrete piles are connected with substantial understatement in describing phenomena accompanying injection piles' loading. From a designing point of view, such understatement means designing with considerable margin. This paper attempts to enrich the experimental knowledge describing phenomena that accompany deep foundation works with the use of small-dimension pile elements, made of cement paste.

9

Eksperymentalna trwałość zmęczeniowa pachwinowych złączy spawanych poddanych obciążeniom cyklicznym

Blacha Ł.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2011

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z. 98

9-10

EN

The paper presents results of fatigue tests of welded joints. Experimental data have been derived from tests carried on as-welded specimens of a transverse stiffener type, submitted to constant amplitude fully reversed axial loading. For the results, statistical evaluation have been undertaken by the means of regression analysis.

10

Rozkłady naprężeń uplastyczniających w czwórnikach rozpęczanych hydromechanicznie z miedzi oraz badanie siły w procesie

Chałupczak J., Miłek T.

Rudy i Metale Nieżelazne

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2004

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R. 49, nr 10-11

529-534

PL

Przedstawiono numeryczne rozkłady naprężeń uplastyczniających, uzyskane przy założonych zmianach ciśnienia, w czwórnikach równo- i różnoprzelotowych z miedzi. Obliczeń dokonano metodą MES wykorzystując oprogramowanie MSC Marc. Zmiana ciśnienia przy rozpęczaniu nie powoduje istotnej zmiany naprężeń uplastyczniających w podobnych strefach czwórników, gdyż sigma p przyjmuje w nich te same zakresy wartości. Natomiast zmniejszenie stosunku d/D wpływa na zmniejszenie naprężeń uplastyczniających w środkowej strefie czwórnika oraz ich zwiększenie w części rurowej. Porównano symulacyjne przebiegi sił spęczających z doświadczalnymi dla różnych stosunków d/D, so/D oraz różnych stosowanych ciśnień. Obliczenia numeryczne wykazały dużą zgodność z wynikami eksperymentalnymi dla założonego mi = 0,15.

EN

The process of hydromechanical bulge forming is a variety of liquid pressure forming. The characteristic feature is that it makes use of the external upsetting force, which considerably simplifies the material flow in the radial direction and prevents the wall from thinning in the bulging area. Hydromechanical bulging is applied mainly to the series production of hydraulic installation and sanitary facilities including tubes with a changeable diameter, T-pipes and cross-joints. The method of hydromechanical bulging used for cross-joint making was patented in 1973. It was used by the patent author for the research on steel T-pipes and cross-joints. It consists in placing a tube segment in a die-cavity, pouring some liquid over it and sealing the faces. As a result the liquid pressure rises and the pipe is upset. The basic parameters of the hydromechanical process of bulge forming are: liquid pressure and axial loading. In the paper numerical distributions of flow stress in hydromechanically bulged copper cross joints are presented. The simulations of hydromechanical bulge forming were performed using MSC Marc software based on the finite element method. The calculation results were compared with the experimental data especially to study axial loading for different ratios d/D, s0/D and for different variations of internal pressure. The results of numerical simulations of axial loading are in good agreement with the experimental data for established mu = 0.15.