• 한국농공학회지
• /
• 제44권3호
• /
• pp.73-84
• /
• 2002

Nominal shear strength of concrete beam is the combined strength of concrete shear strength and steel shear strength in current design code. But Torsional moment strength of concrete is neglected in calculation of the nominal torsional moment strength of reinforced concrete beam in current revised code. Tensile stress of concrete strut between cracks is still in effect due to tension stiffening effect. But the tensile stresses of concrete after cracking are neglected in bending and torsion in design. The torsional behavior is similar to the shear behavior in mechanics. Therefore the torsional moment strength of concrete should be concluded to the nominal torsional moment strength of reinforced concrete beam. To verify the validity of the proposed model, the nominal torsional moment strengths according to CEB, two ACI codes(89, 99) and proposed model are compared to experimental torsional strengths of 55 test specimens found in literature. The nominal torsional moment strengths by the proposed model show the best results.

• 대한토목학회논문집
• /
• 제26권1A호
• /
• pp.117-132
• /
• 2006

3변 고정 1변 자유 직사각형 얇은 판에 대한 기존 해석해를 무차원식으로 유도하고 특성을 분석하였다. Timoshenko와 Woinowsky-Krieger의 방법(1959)은 변장비가 1보다 작은 경우에만 제한적으로 해가 존재하여 처짐 특성에 대한 실용적인 해가 되지 않음을 밝혔다. 굴정(堀井)와 본(本)의 방법(1968)에 수치안정을 위한 항을 추가하여 최대 150개 항까지 구성된 급수해를 구하였고 이로부터 계산한 휨 모멘트의 수렴을 분석하였다. 수정 굴정(堀井)와 본(本)의 방법은 모든 변장비에 대한 처짐 특성을 구할 수 있으나 고정단과 자유단이 접하는 교차점에서의 모멘트 계산은 자유단 경계조건을 만족하지 않으며 그 원인을 분석하였다.

• Steel and Composite Structures
• /
• 제20권1호
• /
• pp.57-70
• /
• 2016

The predominant type of buckling that I-steel concrete composite beams experience in the negative moment area is distortional buckling. The key factors that affect distortional buckling are the torsional and lateral restraints by the bottom flange. This study thoroughly investigates the equivalent lateral and torsional restraint stiffnesses of the bottom flange of an I-steel concrete composite beam under negative moments. The results show a coupling effect between the applied forces and the lateral and torsional restraint stiffnesses of the bottom flange. A formula is proposed to calculate the critical buckling stress of the I-steel concrete composite beams under negative moments by considering the lateral and torsional restraint stiffnesses of the bottom flange. The proposed method is shown to better predict the critical bending moment of the I-steel composite beams. This article introduces an improved method to calculate the elastic foundation beams, which takes into account the lateral and torsional restraint stiffnesses of the bottom flange and considers the coupling effect between them. The results show a close match in results from the calculation method proposed in this paper and the ANSYS finite element method, which validates the proposed calculation method. The proposed calculation method provides a theoretical basis for further research on distortional buckling and the ultimate resistance of I-steel concrete composite beams under a variable axial force.

• Steel and Composite Structures
• /
• 제36권3호
• /
• pp.261-272
• /
• 2020

A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제3권1호
• /
• pp.95-104
• /
• 2011

As sea state harsher in the ocean space, more large motion and wave loads occurs on ships hull by non-linear phenomena. To consider nonlinear effect on ships hull in the structural design verification, the direct calculation method with numerical approach is used rather than rule values for the reliable accuracy. In this paper, the non-linear wave loads analysis in time domain is performed by using a Rankine Panel Method together with numerical schemes. Linear calculations have been carried out based on DNV CSA-2 notation to generate the motion responses and wave loads of large ships. By short and long term analysis, the design wave amplitudes are selected for the nonlinear analysis. The maximum wave induced bending moment in hogging and sagging conditions are calculated in the nonlinear analysis. Also, the green water effect on the wave induced vertical bending moment was investigated. The results show the vertical bending moments are more influenced by green water in sagging condition than in hogging condition due to green water loading.

• Steel and Composite Structures
• /
• 제45권5호
• /
• pp.749-766
• /
• 2022

This paper investigates the seismic performance of exposed RCFST column-base joints, in which the high-strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens with different axial force ratios (n = 0, 0.25, and 0.5) were tested under cyclic loadings. Finite element analysis (FEA) models were validated in the basic indexes and failure mode. The hysteresis behavior of the exposed RCFST column-base joints was studied by the parametrical analysis including six parameters: width of column (D), width-thickness ratio (D/t), axial force ratio (n), shear-span ratio (L/D), steel tube strength (f_y) and concrete strength (f_c). The bending moment of the exposed RCFST column-base joint increased with D, f_y and f_c. But the D/t and L/D play a little effect on the bending capacity of the new column-base joint. Finally, the calculation formula is proposed to assess the bending moment capacities, and the accuracy and stability of the formula are verified.

• 대한조선학회논문집
• /
• 제43권4호
• /
• pp.484-493
• /
• 2006

Recently, direct load analysis using ship motion program is required to confirm structural safety for the Post-Panamax class large container carrier. However, there is no exact comparative study data for structural response between 20 and 30 wave load. So, in this paper, to compare the hull girder stress response between 20 versus 3D wave load calculation method, direct load analysis and global F.E analysis have been performed for three kinds of large container vessels using each 20 and 30 wave load calculation program. The results of 2D wave load RAO(Response Amplitude Operator) of each dominant load parameter(vertical, torsional and horizontal moment) are generally bigger than that of 30 results, especially in vertical wave bending moment. And the results of structural analysis based on the equivalent design wave method shows that there is a big difference in view of stress, but the stress distribution is very similar for each wave load case.

• Steel and Composite Structures
• /
• 제21권3호
• /
• pp.537-551
• /
• 2016

A new type of composite beam which consists of a wide flange steel shape beam and an innovative type of composite slab was introduced. The composite slab is composed of concrete slab and normal flat steel plates, which are connected by perfobond shear connectors (PBL shear connectors). This paper describes experiments of two large-scale specimens of that composite beam. Both specimens were loaded at two symmetric points for 4-point loading status, and mechanical behaviors under hogging and sagging bending moments were investigated respectively. During the experiments, the crack patterns, failure modes, failure mechanism and ultimate bending capacity of composite beam specimens were investigated, and the strains of concrete and flat steel plate as well as steel shapes were measured and recorded. As shown from the experimental results, composite actions were fully developed between the steel shape and the composite slab, this new type of composite beams was found to have good mechanical performance both under hogging and sagging bending moment with high bending capacity, substantial flexure rigidity and good ductility. It was further shown that the plane-section assumption was verified. Moreover, a design procedure including calculation methods of bending capacity of this new type of composite beam was studied and proposed based on the experimental results, and the calculation methods based on the plane-section assumption and plastic theories were also verified by comparisons of the calculated results and experimental results, which were agreed with each other.

• 대한기계학회논문집A
• /
• 제30권2호
• /
• pp.120-127
• /
• 2006

The fatigue behavior of LIPCA was so sensitive to the manufacturing condition, the environmental factors and the change of the test apparatus. Therefore, we could be considering not only the relationship between the stroke range $({\Delta}h)$ and actuating frequency but also the relationship between the stroke range $({\Delta}h)$ and the total effective moment $(M^E)$. Thus, this study proposed the calculation method of the applying $M^E$ when the $({\Delta}h)$ of LIPCA was increased from 1.mm to 20mm. To estimate the relationship between the total effective moment $(M^E)$ and the Bernoulli-Euler bending moment (M) was reviewed. And the residual stress distribution of LIPCA and THUNDER using the CLT was evaluated. In conclusions, converting the $({\Delta}h)$ of LIPCA to the radius of curvature (p) and calculating the $(M^E)$, it was found that the p by the $M^E$ changed similarly as the $({\Delta}h)$. It was found that the $M^E$ was 2.2 times as the M. While CFRP and PZT of LIPCA, which had the superior compressive characteristic, had the compressive residual stress, GFRP was subject to the tensile residual stress. Since this reversed configuration between the compressive residuals stress and the tensile one was made, the requirement of the stroke range $({\Delta}h)$ increase was satisfied.

• 대한조선학회지
• /
• 제17권2호
• /
• pp.17-20
• /
• 1980

The shearing forces and bending moments acting on the tanker model[1] of $C_B$ 0.82 in regular oblique waves of shallow water are investigated by numerical calculations. The new strip method was adopted. It is concluded that in the shallow water shearing forces and the bending moments acting on the tanker model are higher than those of deep water waves by the present numerical investigations. The wave bending moment at the midship section is roughly twice of deep water value in the shallow of H/T less than 2. in this calculation.