• Steel and Composite Structures
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• 제13권3호
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• pp.295-308
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• 2012

This paper experimentally investigated the buckling capacity of built-up steel columns mainly, Cruciform Columns (CC) and Side-to-Side (SS) columns fabricated from two Universal Beam (UB) sections. A series of nine experimental tests comprised of three UB sections, three CC sections and three SS sections with different lengths were tested to failure to measure the ultimate axial capacity of each column section. The lengths used for each category of columns were 1.8, 2.0, and 2.2 m with slenderness ratios ranging from 39-105. The measured buckling loads of the tested specimens were compared with the predicted ultimate axial capacity using Eurocode 3, AISC LRFD, and BS 5959-1. It was observed that the failure modes of the specimens included flexural buckling, local buckling and flexural-torsional buckling. The results showed that the ultimate axial capacity of the tested cruciform and side-by-side columns were higher than the code predicted design values by up to 20%, with AISC LRFD design values being the least conservative and the Eurocode 3 design values being the most conservative. This study has concluded that cruciform column and side-to-side welded flange columns using universal beam sections are efficient built-up sections that have larger ultimate axial load capacity, larger stiffness with saving in the weight of steel used compared to its equivalent universal beam counterpart.

• 한국해양공학회지
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• 제3권2호
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• pp.577-577
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• 1989

In this paper, a detail evaluation of ultimate strength of offshore unstiffened tubular members with bending and local denting damage which are subjected to combined axial force and bending moment and to component load is presented through theoretical and experimental approaches. Based upon the results obtained here, the damage effect on the ultimate strength of tubular member under combined loads and component load is investigated.

• 한국해양공학회지
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• 제3권2호
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• pp.77-86
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• 1989

In this paper, a detail evaluation of ultimate strength of offshore unstiffened tubular members with bending and local denting damage which are subjected to combined axial force and bending moment and to component load is presented through theoretical and experimental approaches. Based upon the results obtained here, the damage effect on the ultimate strength of tubular member under combined loads and component load is investigated.

• 한국항해항만학회지
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• 제31권3호
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• pp.235-245
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• 2007

선체의 갑판부와 선저부 그리고 해양구조물의 기본적인 구조는 보강판이다. 보강판넬은 한쪽방향으로 위치한 보강재 혹은 종/횡 방향으로 복잡하게 위치한 구조를 이루고 있으며, 후자의 모델을 그릴리지 구조라고 부른다 선체구조설계 단계에서 선박의 종강도 평가는 가장 중요한 항목이다. 일반적으로, 극심한 해상상태에 놓인 선박의 선저부에는 호깅조건에 의해 발생되는 횡모멘트에 기인하여 압축하중이 작용하게 되며, 이와 동시에 수압하중 작용으로 인한 국부휭모멘트가 작용된다. 본 논문에서는, 구조해석 결과의 검증을 위해서 여러 가지 해석프로그램 및 현재 사용되고 있는 선급룰과의 비교를 하여 횡하중의 영향에 따른 압축최종강도에 대해 분석하고, 여러 가지 설계변수를 변화하여, 각각의 영향을 검토하고, 최종적으로 조합하중 조건에서의 횡하중의 영향에 대해서 분석하였다. 본 연구에서 얻어진 결과들은 최종한계상태설계법에 기반을 두고, 조합하중이 작용하는 선체보강판의 구조강도 거동에 대해서 하중성분에 대한 관계를 고찰하였다.

• Steel and Composite Structures
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• 제47권3호
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• pp.437-450
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• 2023

A half open cross section built-up column, namely cold-formed thin-walled steel built-up column with 12-limbsection (CTSBC-12) is put forward. To deeply reveal the mechanical behaviors of CTSBC-12 under axial compression and put forward its calculation formula of axial bearing capacity, based on the previous axial compression experimental research, the finite element analysis (FEA) is conducted on 9 CTSBC-12 specimens, and then the variable parameter analysis is carried out. The results show the FEA is in good agreement with the experimental research, the ultimate bearing capacity error is within 10%. When the slenderness ratio is more than 96.54, the ultimate bearing capacity of CTSBC-12 decreases rapidly, and the failure mode changes from local buckling to global buckling. With the local buckling failure mode unchanged, the ultimate bearing capacity decreases gradually as the ratio of web height to thickness increases. Three methods are used for calculating the ultimate bearing capacity, the direct strength method of AISI S100-2007 gives result of ultimate axial load which is closest to the test and FEA results. But for simplicity and practicality, a simplified axial bearing capacity formula is proposed, which has better calculation accuracy with the slenderness ratio changing from 30 to 100.

• Computers and Concrete
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• 제33권5호
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• pp.509-518
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• 2024

In this study, we investigated the effect of shear-key placement on the performance of grouted connections in offshore wind-turbine structures. Considering the challenges of height control during installation, we designed and analyzed three grouted connection configurations. We compared the crack patterns and strain distribution in the shear keys under axial loading. The results indicate that the misalignment of shear keys significantly influences the ultimate load capacity of grouted connections. Notably, when the shear keys were positioned facing each other, the ultimate load decreased by approximately 15%, accompanied by the propagation of irregular cracks in the upper shear keys. Furthermore, the model with 50% misalignment in the shear-key placement exhibited the highest ultimate strength, indicating a more efficient load resistance than the reference model. This indicates that tensile-load-induced cracking and the formation of compressive struts in opposite directions significantly affect the structural integrity of grouted connections. These results demonstrate the importance of considering buckling effects in the design of grouted connections, particularly given the thin and slender nature of the inner sleeves. This study provides valuable insights into the design and analysis of offshore wind-turbine structures, highlighting the need for refined design formulas that account for shifts in shear-key placement and their structural implications.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.583-591
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• 2005

The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design of ship structures, it is of crucial importance to bitter understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

• Structural Engineering and Mechanics
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• 제66권3호
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• pp.305-315
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• 2018

Interaction of lateral loading, combined with axial force needs to be determined with care in reinforced concrete (RC) one-dimensional structural members (1D SMs) such as beam-columns (BCs) and columns. RC 1D SMs under heavy axial loading are known to fail by brittle mode and small lateral displacements. In this paper, a macro element-based algorithm is proposed to analyze the RC 1D SMs under monotonic or cyclic combined loading. The 1D SMs are discretized into macro-elements (MEs) located between the critical sections and the inflection points. The critical sections are discretized into fixed rectangular finite elements (FRFE). The nonlinear behavior of confined and unconfined concretes and steel elements are considered in the proposed algorithm. The proposed algorithm has been validated by the results of experimental tests carried out on full-scale RC structural members. The evolution of ultimate strain at extreme compression fiber of a rectangular RC section for different orientations of lateral loading shows that the ultimate strain decreases with increasing the axial force. In the examined cases, this ultimate strain ranges from 0.0024 to 0.0038. Therefore, the 0.003 value given by ACI-318 code for ultimate strain, is not conservative and valid for the combined load cases with significant values of axial force (i.e. for the axial forces heavier than 70% of the ultimate axial force).

• Geomechanics and Engineering
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• 제12권6호
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• pp.899-917
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• 2017

Sixty four tests were performed in a steel tank to investigate the axial responses of piles driven into organic soil prepared at two different densities using a drop hammer. Four different pile materials were used: wood, steel, smooth concrete, and rough concrete, with different length to diameter ratios. The results of the load tests showed that the shaft load capacity of rough concrete piles continuously increased with pile settlement. In contrast, the others pile types reached the ultimate shaft resistance at a settlement equal to about 10% of the pile diameter. The ratios of base to shaft capacities of the piles were found to vary with the length to diameter ratio, surface roughness, and the density of the organic soil. The ultimate unit shaft resistance of the rough concrete pile was always greater than that of other piles irrespective of soil condition and pile length. However, the ultimate base resistance of all piles was approximately close to each other.

• Computers and Concrete
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• 제31권6호
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• pp.513-525
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• 2023

This research presents the experimental and theoretical evaluations on circular steel-fiber-reinforced-concrete (SFRC) columns reinforced by glass-fiber-reinforced-polymer (GFRP) rebar under the axial compressive loading. Test programs were designed to investigate and compare the effect of different parameters on the structural behavior of columns by performing tests. Theses variables included conventional concrete (CC), fiber concrete (FC), steel/GFRP longitudinal rebars, and transversal rebars configurations. A total of 16 specimens were constructed and categorized into four groups in terms of different rebar-concrete configurations, including GFRP-rebar-reinforced-CC columns (GRCC), GFRP-rebar-reinforced-FC columns (GRFC), steel-rebar-reinforced-CC columns (SRCC) and steel-rebar- reinforced-FC columns (SRFC). Experimental observations displayed that failure modes and cracking patterns of four groups of columns were similar, especially in pre-peak branches of load-deflection curves. Although the average ultimate axial load of columns with longitudinal GFRP rebars was obtained by 17.9% less than the average ultimate axial load of columns with longitudinal steel rebars, the average axial ductility index (DI) of them was gained by 10.2% higher than their counterpart columns. Adding steel fibers (SFs) into concrete led to the increases of 7.7% and 6.7% of the axial peak load and the DI of columns than their counterpart columns with CC. The volumetric ratio had greater efficiency on peak loads and DIs of columns than the type of transversal reinforcement. A simple analytical equation was proposed to predict the axial compressive capacity of columns by considering the axial involvement of longitudinal GFRP rebars, volumetric ratio, and steel spiral/hoop rebar. There was a good correlation between test results and predictions of the proposed equation.