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| Investigation of Effect of Steps in Inelastic-Buckling Strength of I-Beams Subjected to Two Concentrated Loads Using Experimental Tests, Finite Element Analysis and Proposed Equations |
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| Investigation of Effect of Steps in Inelastic-Buckling Strength of I-Beams Subjected to Two Concentrated Loads Using Experimental Tests, Finite Element Analysis and Proposed Equations |
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Albert S. Surla, Jong Sup Park |
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| Abstract |
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This paper is focused on the analysis of results obtained in the experimental tests on singly symmetric doubly stepped I-beams. Specifically, two point load tests were conducted on the beams having non-compact flange sections. The tests were conducted to investigate the inelastic buckling behavior of the stepped beams. For every specimen, the main parameters are the unbraced length and the stepped beam parameters. Four short span specimens were tested and the monosymmetric ratio of all the beams was fixed at 0.7. The unbraced lengths were 3 meters and 4 meters. Furthermore, the buckling capacity of the stepped beams were investigated by using finite element analyses. The results were also compared to equations proposed by different researchers which determine the buckling capacity of stepped beams. Also, values recommended by various codes of practice on prismatic beams were used as a reference to determine the accuracy of the finite element models. Results showed that the values yielded by FEA had a good correlation with the values obtained from the tests. Meanwhile, the equations used to determine the strengths of the stepped beams yielded over conservative and unconservative results. The significant effect of steps in increasing the capacity of the beams was also observed. |
| Key Words:
Non-compact; Stepped beam; Inelastic buckling; Experimental test |
| 요지 |
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본 논문은 일축대칭 I형 양단스텝의 극한강도를 실험적으로 평가하는 데 목적을 두고 있다. 상부플랜지에 두 개의 집중하중이 작용하는 하중조건을 고려하였으며 상하부 플랜지에는 비조밀 단면이 적용되어 비조밀 플랜지 단면이 극한강도에 미치는 여향을 검토하였따. 3m와 4m 길이를 가지는 실험체 각각 2개씩 총 4개의 스텝보 실험체에 극한파괴실험을 실시하였으며, 비탄성구간에 존재하는 본 실험체의 설계강도를 국외 설계기준 및 유한요소해석을 통하여 추정하고 상세 비교분석하였다. 또한 기존 연구자들이 제안한 제안식과도 비교하여 기존 제안식의 적용성을 평가하였다. 실험을 통해 얻어진 극한강도는 유한요소해석 결과와는 잘 일치하는 것을 비교분석을 통하여 알 수 있었고, 기존 제안식과는 매우 안전측 또는 과소한 결과를 나타낸 것으로 나타났다. 또한 비탄성구간에서도 스텝보보강이 극한강도를 증가시키는 것을 확인할 수 있었다. |
| 핵심용어:
비조밑단면; 스텝보; 비탄성 좌굴; 파괴실험 |
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