• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.903-906
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• 2005

The purpose of this paper is to investigate free vibrations and critical loads of the uniform Beck's columns with a tip spring, carrying a tip mass. The ordinary differential equation governing free vibrations of such Beck's column subjected to a follower force is derived based on the Bernoulli-Euler beam theory. Both the divergence and flutter critical loads are calculated from the load-frequency curves that are obtained by solving the differential equation numerically. The critical loads are presented in the figures as functions of various non-dimensional system parameters such as the mass moment of inertia and spring parameter.

• Computers and Concrete
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• 제25권2호
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• pp.111-118
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• 2020

The construction field must always explore sustainable ways of using its raw materials. Studying the environmental impact generated by reinforced concrete raw materials during their production and transportation can contribute to reducing this impact. This paper initially presents the carbon dioxide emissions from reinforced concrete raw materials, quantified per kilo of raw material and per cubic meter of concrete with different characteristic strengths, for southern Brazil. Subsequently, reinforced concrete elements were optimized to minimize their environmental impact and cost. It was observed that lower values of carbon dioxide emissions and cost savings are generated for less resistant concrete when the structural element is a beam, and that reductions in the cross section dimensions of the beams, sized based on the use of higher strength concrete, may not compensate for the increased environmental impact and costs. For the columns, the behavior differed, presenting lower values of carbon dioxide emissions and costs for higher concrete strengths. The proposed methodology, as well as the results obtained, can be used to support structural projects that have less impact on the environment.

• 국제초고층학회논문집
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• 제10권3호
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• pp.219-227
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• 2021

This building is a forty-eight story, 170 meters high multiple dwelling house with Dual Frame System (DFS), a coupled vibration system connecting two independent structures with hydraulic dampers. Generation of large deformation between two structures during earthquakes contributes to make the hydraulic dampers effective. To improve the aseismic performance more, this building adopts DFS hybrid system that consists of DFS and base isolation system. About typical floors, columns and beams are constructed with LRV precast concrete method that shorten the construction period greatly by integrating column-beam joints in column members.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.214-215
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• 2020

The 3D scanning technology is being introduced for quality inspection of building construction. Therefore, this study tried to confirm whether it is possible to check the quality of rebar by using 3D scanning. After rebar placed on the formwork slab was scanned with a 3D scanner, the rebar spacing was confirmed by overlapping with the CAD drawing. As a result, the 3D scanner was able to check the quality of rebar work on one floor at a time. Therefore, 3D scanning could be used for quality inspection of rebar works such as columns, beam and girders, walls, and slabs in the future.

• Steel and Composite Structures
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• 제50권5호
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• pp.531-548
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• 2024

This paper presents an experimental investigation into the progressive collapse behavior of composite steel-concrete frames under various column removal scenarios. This study involves testing two two-bay, two-story composite frames featuring CFST columns and profiled steel decking composite slabs. Two removal scenarios, involving the corner column and middle column, are examined. The paper reports on the overall and local failure modes, vertical force-deformation responses, and strain development observed during testing. Findings indicate that structural failure initiates due to fracture and local buckling of the steel beam. Moreover, the collapse resistance and ductility of the middle column removal scenario surpass those of the corner column removal scenario. Subsequent numerical analysis reveals the significant contribution of the composite slab to collapse resistance and capacity. Additionally, it is found that horizontal boundary conditions notably influence the collapse resistance in the middle column removal scenario only. Finally, the paper proposes a simplified calculation method for collapse resistance, which yields satisfactory predictions.

• 콘크리트학회논문집
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• 제14권6호
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• pp.823-829
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• 2002

철근콘크리트 기둥-철골 보 합성골조는 철근콘크리트와 철골부재의 재료적인 장점을 살린 합리적인 구조물이나, 이질 재료간의 접합으로 인해 보-기둥 접합부의 설계와 해석에서는 많은 구조적인 문제점들이 생기게 된다. 이 연구에서는 철골 보의 하중이 콘크리트 기둥으로 원활히 전달되면서 현장 시공성이 우수한 새로운 형태의 합성골조 접합부의 형식을 제안하고자 한다. 이 연구에서 고안된 접합부는 H 형강을 반분한 T 형강을 시스템 내부 및 외부의 모든 응력 전달 요소를 연결하는 주요 요소로 하고, 보 플랜지의 인장력 전달을 위해 한 방향은 고강도 강봉을, 이와 직교하는 방향은 강재 연결판을 사용하였다. 스티프너보강된 ㄱ형강을 사용하여 보 플랜지의 인장력을 기둥면에 전달하도록 하였으며, T 형강에 용접된 전단 접합판을 보의 웨브와 고력볼트로 접합하여 전단력을 지지하도록 설계하였다. 이 연구에서는 보의 플랜지로부터 스티프너 보강된 ㄱ형강을 통해 강봉이나 연결판으로 전달되는 휨모멘트 전달성능을 확인하고자 구조성능 시험을 수행하였다. 시험체는 실제 보-기둥 접합부를 모델로 하여, 실물크기로 4개가 제작되었으며, 구조실험은 철골 보의 양 단부를 단순지지한 상태에서 기둥 중앙에 집중하중을 가해 보-기둥 접합부에 휨모멘트와 전단력을 작용시키는 방식으로 진행되었다. 실험결과, 이 연구에서 제안된 접합부는 현장 적용이 가능한 가공성과 운반성 및 시공성을 가지며, 철골 보-접합용 ㄱ형강 -연결용 강봉 및 연결판에 의한 응력전달이 매우 순조로운 것으로 나타났다.

• 한국공간구조학회논문집
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• 제12권3호
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• pp.63-70
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• 2012

본 연구에서는 변위기반 성능설계 개념에 의해 기존 철근콘크리트 기둥과 콘크리트에 강재를 매입한 SRC 합성기둥에 대하여 최대 설계지진 가속도에 대한 내진성능개선의 성능설계을 비교하였다. SRC 합성기둥은 구조물의 강도를 증가시킬 뿐 아니라 연성도를 증가시키는 효과가 있다. SRC 합성기둥의 단면은 H형 강재와 원형의 중공 강관을 매입한 형태로 구성되어 있다. SRC 합성기둥에 대한 P-M상관도와 단면 공칭휨모멘트를 분석하고 이를 바탕으로 SRC 합성기둥에 대한 설계 변위 추정을 위해 변위기반 내진 설계 알고리즘을 제시하였다. 성능기반설계에 의한 성능개선설계를 위하여 목표성능변위 및 설계지진가속도 조건에 대해 직접변위 기반 설계방법 및 변위계수법에 의한 내진성능개선 설계 방법을 제시하였다. SRC 합성기둥은 기존 RC 기둥과 비교하여 성능개선 설계 결과 변위 연성비 및 변위성능에서 크게 개선된 성능설계 결과를 나타내었다.

• Steel and Composite Structures
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• 제26권6호
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• pp.745-757
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• 2018

The inclusion of a ductile steel bracing as means of repairing an earthquake-damaged bridge bent is evaluated and experimentally assessed for the purposes of restoring the damaged bent's strength and stiffness and further improving the energy dissipation capacity. The study is focused on substandard reinforced concrete multi-column bridge bents constructed in the 1950 to mid-1970 in the United States. These types of bents have numerous deficiencies making them susceptible to seismic damage. Large-scale experiments were used on a two-column reinforced concrete bent to impose considerable damage of the bent through increasing amplitude cyclic deformations. The damaged bent was then repaired by installing a ductile fuse steel brace in the form of a buckling-restrained brace in a diagonal configuration between the columns and using post-tensioned rods to strengthen the cap beam. The brace was secured to the bent using steel gusset plate brackets and post-installed adhesive anchors. The repaired bent was then subjected to increasing amplitude cyclic deformations to reassess the bent performance. A subassemblage test of a nominally identical steel brace was also conducted in an effort to quantify and isolate the ductile fuse behavior. The experimental data from these large-scale experiments were analyzed in terms of the hysteretic response, observed damage, internal member loads, as well as the overall stiffness and energy dissipation characteristics. The results of this study demonstrated the effectiveness of utilizing ductile steel bracing for restoring the bent and preventing further damage to the columns and cap beams while also improving the stiffness and energy dissipation characteristics.

• Structural Engineering and Mechanics
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• 제74권3호
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• pp.395-406
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• 2020

Many prefabricated concrete frame joints have been proposed, and most of them showed good seismic performance. However, there are still some limitations in the proposed fabricated joints. For example, for prefabricated prestressed concrete joints, prefabricated beams and prefabricated columns are assembled as a whole by the pre-stressed steel bar and steel strand in the beams, which brings some troubles to the construction, and the reinforcement in the core area of the joints is complex, and the mechanical mechanism is not clear. Based on the current research results, a new type of fabricated joint of prestressed concrete beams and confined concrete columns is proposed. To study the seismic performance of the joint, the quasi-static test is carried out. The test results show that the nodes exhibit good ductility and energy dissipation. According to the experimental fitting method and the "fixed point pointing" law, the resilience model of this kind of nodes is established, and compared with the experimental results, the two agree well, which can provides a certain reference for elasto-plastic seismic response analysis of this type of structure. Besides, based on the analysis of the factors affecting the shear capacity of the node core area, the formula of shear capacity of the core area of the node is proposed, and the theoretical values of the formula are consistent with the experimental value.

• Structural Engineering and Mechanics
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• 제78권4호
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• pp.485-496
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• 2021

So far analytical methods on collapse assessment of three-dimensional (3-D) steel frames have mainly focused on a single-column-removal scenario. However, the collapse of the Federal Building in the US due to car bomb explosion indicated that the loss of multiple columns may occur in the real structures, wherein the structures are more vulnerable to collapse. Meanwhile, the General Services Administration (GSA) in the US suggested that the removal of side columns of the structure has a great possibility to cause collapse. Therefore, this paper analytically deals with the robustness of 3-D steel frames in a two-side-column-removal (TSCR) scenario. Analytical method is first proposed to determine the collapse resistance of the frame during this column-removal procedure. The reliability of the analytical method is verified by the finite element results. Moreover, a design-based methodology is proposed to quickly assess the robustness of the frame due to a TSCR scenario. It is found the analytical method can reasonably predict the resistance-displacement relationship of the frame in the TSCR scenario, with an error generally less than 10%. The parametric numerical analyses suggest that the slab thickness mainly affects the plastic bearing capacity of the frame. The rebar diameter mainly affects the capacity of the frame at large displacement. However, the steel beam section height affects both the plastic and ultimate bearing capacity of the frame. A case study on a six-storey steel frame shows that the design-based methodology provides a conservative prediction on the robustness of the frame.