• Title/Summary/Keyword: B.Arch

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Assessment of a concrete arch bridge using static and dynamic load tests

  • Caglayan, B. Ozden;Ozakgul, Kadir;Tezer, Ovunc
    • Structural Engineering and Mechanics
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    • v.41 no.1
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    • pp.83-94
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    • 2012
  • Assessment of a monumental concrete arch bridge with a total length of 210 meters having three major spans of 30 meters and a height of 65 meters, which is located in an earthquake-prone region in southern part of the country is presented in this study. Three-dimensional finite element model of the bridge was generated using a commercially available general finite element analysis software and based on the outcomes of a series of in-depth acceleration measurements that were conducted on-site, the model was refined. By using the structural parameters obtained from the dynamic and the static tests, calibrated model of the bridge structure was obtained and this model was used for necessary calculations regarding structural assessment and evaluation.

Damage inspection and performance evaluation of Jilin highway double-curved arch concrete bridge in China

  • Naser, Ali Fadhil;Zonglin, Wang
    • Structural Engineering and Mechanics
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    • v.39 no.4
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    • pp.521-539
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    • 2011
  • Jilin highway concrete bridge is located in the center of Jilin City, which is positioned in the middle part in Jilin Province in the east north of China. This bridge crosses the Songhua River and connects the north and the south of Jilin City. The main purpose of damages inspection of the bridge components is to ensure the safety of a bridge and to identify any maintenance, repair, or strengthening which that need to be carried out. The damages that occur in reinforced concrete bridges include different types of cracks, scalling and spalling of concrete, corrosion of steel reinforcement, deformation, excessive deflection, and stain. The main objectives of this study are to inspect the appearance of Jilin highway concrete bridge and describe all the damages in the bridge structural members, and to evaluate the structural performance of the bridge structure under dead and live loads. The tests adopted in this study are: (a) the depth of concrete carbonation test, (b) compressive strength of concrete test, (c) corrosion of steel test, (d) static load test, and (e) dynamic load test. According to the damages inspection of the bridge structure appearance, most components of the bridge are in good conditions with the exception arch waves, spandrel arch, deck pavement of new arch bridge, and corbel of simply supported bridge which suffer from serious damages. Load tests results show that the deflection, strain, and cracks development satisfy the requirements of the standards.

Experimental study on creep behavior of fly ash concrete filled steel tube circular arches

  • Yan, Wu T.;Han, Bing;Zhang, Jin Q.;Xie, Hui B.;Zhu, Li;Xue, Zhong J.
    • Steel and Composite Structures
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    • v.27 no.2
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    • pp.185-192
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    • 2018
  • Fly ash can significantly improve concrete workability and performance, and recycling fly ash in concrete can contribute to a cleaner environment. Since fly ash influences pozzolanic reactions in concrete, mechanical behaviors of concrete containing fly ash differ from traditional concrete. Creep behaviors of fly ash concrete filled steel tube arch were experimentally investigated for 10% and 30% fly ash replacement. The axes of two arches are designed as circular arc with 2.1 m computed span, 0.24 m arch rise, and their cross-sections are all in circular section. Time dependent deflection and strain of loading and mid-span steel tube were measured, and long term deflection of the model arch with 10% fly ash replacement was significantly larger than with 30% replacement. Considering the steel tube strain, compressive zone height, cross section curvature, and internal force borne by the steel tube, the compressive zone height and structural internal forces increased gradually over time due to concrete creep. Increased fly ash content resulted in more significant neutral axis shift. Mechanisms for internal force effects on neutral axis height were analyzed and verified experimentally.

A STUDY ON THE ACCURACY OF DENTAL CAST AND DIE MATERIALS USING PHOTO-SCANNING (사진 주사(走査)를 이용한 치과용 모형재의 정확도에 관한 연구)

  • Yang, Seong-Wook;Lim, Ju-Hwan;Cho, In-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.34 no.2
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    • pp.320-334
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    • 1996
  • Dental cast and die materials are essential material using in almost dental prsthodontic procedure and it's most important requirement is accuracy for reqorducing the oral anatomical structures. In this study, 5 abutments A, B, C, D, E were fabricated on the metal master model to simulate the arch form and specimens were poured with 4 cast materials. Inter-abutment distances, A-B, A-C, A-D, A-E, B-C, B-D were calculated using the photo-scanning and the deviations from the metal master model were also evaluated. The results were as follows; 1. The distance between A-B, A-C, A-D, A-E, B-C, B-D of the abutments A, B, C, D, E of each cast material was calculated. And after comparing the deviations between the metal master model. $Fujirock^{(R)}$ showed the lowest value with $0.20{\pm}0.22mm$, and the deviation increased in the order of $Suprastone^{(R)}$, Epoxy $Die^{(R)}$, Die $Keen^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and Epoxy $Die^{(R)}$, Die $Keen^{(R)}$. 2. In each calculation area, the difference in measurements between cast material and metal master model showed singificant difference between A-B and Cross arch measure-ments of A-D, B-D, A-E(p<0.05). 3. The difference in measurements between cast material and metal master model in the A-B area showed $Fujirock^{(R)}$ to be the lowest with $0.05{\pm}0.04$mm and increased in the order of Die $Keen^{(R)}$, $Suprastone^{(R)}$, Epoxy $Dies^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and $Suprastone^{(R)}$, Epoxy $Die^{(R)}$ (p<0.05). 4. The difference in measurements between cast material and metal master model in the B-C area showed $Fujirock^{(R)}$ to bo the lowest with $0.17{\pm}0.11$mm and increased in the order of $Suprastone^{(R)}$, Die $Keen^{(R)}$, Epoxy $Dies^{(R)}$. There was significant difference between $Fujirock^{(R)}$ and Die $Keen^{(R)}$, Epoxy $Die^{(R)}$(p<0.05). 5. The difference in measurements between cast material and metal master model in the B-D area showed $Fujirock^{(R)}$ to bo the lowest with $0.13{\pm}0.07$mm, Epoxy $Dies^{(R)}$and increased in the order of $Suprastone^{(R)}$, Die $Keen^{(R)}$. There was significant difference between $Fuji-rock^{(R)}$ and Die Keen(p<0.05). 6. In this experiment, Epoxy $Dies^{(R)}$ showed mean contraction in every calculation area. And when reconstruction cross arch restorations it is thought that distortion should be considered in every cast material.

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Pullout Test of Headed Reinforcement 2: Deep Embedment

  • Choi, Dong Uk;Shin, InYong
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.1091-1096
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    • 2003
  • Pullout tests of single headed bars using plain concrete blocks indicate that the embedment depth of $10d_b$ is in general required for the headed bars to develop pullout strength equivalent to 125% of bar yield strength. In this experimental study, test results of multiple headed bars installed in reinforced concrete column sections are presented. Test variables included embedment depth, column main reinforcement ratio, and spacing of column ties. 2D29 bars were pulled out at one time from normal strength concrete. Test results indicated that the embedment depths, column tie spacings, and column main reinforcement ratios all influenced the pullout strengths of the headed bars. When the embedment depth was not sufficient, narrow tie spacings especially resulted in increased pullout strengths of the headed bars. Test results also indicated that the embedment depth of 15㏈ was sufficient for the closely spaced two headed bars (head-to-head spacing =$6d_b$) to develop pullout strength equivalent to 125% of the bar yield strength.

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Seismic Behavior of Precast Frames with Hybrid Beam-Column Connections

  • Moon, Jeong-Ho;Lee, Yong-Ju
    • KCI Concrete Journal
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    • v.11 no.3
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    • pp.191-199
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    • 1999
  • A Precast frame system with hybrid beam-column connections was proposed in this study. An analytical study evaluated the system under seismic loadings. Four buildings with different heights were modeled in which each building had three types of joint details (A. B, C). Thus, twelve buildings were examined with variables such as building height and joint detail. Four earthquake records were applied to the buildings as input ground motions. All the records were normalized to the intensity of 0.25g to assess behavior under the same intensity of seismic excitation. All the joint types showed almost identical results except for the Mexico earthquake which was scaled up from 0. 1g to 0.25g. Buildings with the type C joint exhibited the largest deflection for the Mexico earthquake. It was concluded that type B joint could be used in a high seismic zone and the type C joint could possibly be used in the regions of low to medium seismic activity.

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One-stage Repair of Interrupted Aortic Arch with Ventricular Septal Defect and Valvular Aortic Stenosis - A case report- (심실 중격 결손과 대동맥 판 협착을 가진 대동맥 궁 단절의 일차 완전 교정술 -1예 보고-)

  • Cho, Joon-Yong;Jeong, Young-Kyun;Lee, Jong-Tae;Kim, Kyu-Tae;Chang, Bong-Hyun
    • Journal of Chest Surgery
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    • v.38 no.12 s.257
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    • pp.856-859
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    • 2005
  • A male neonate was referred to our hospital with facial cyanosis and tachypnea at 19 days of age. Two-dimensional echocardiography showed type B interrupted aortic arch, posterior malalignment ventricular septal defect and valvular aortic stenosis. A new surgical repair was done with biventricular repair and neo-aortic arch reconstruction. Left ventricular outflow track (LVOT) was consisted of aortic valve and pulmonic valve. Right ventricular outflow (RVOT) track was reconstructed with extracardiac conduit. Postoperative two-dimensional echocardiography showed no stenosis and turbulency flow on LVOT and RVOT.

A Study on the Evaluation of the Daylighting Performance in the Sound Barrier Tunnel (축소모형을 이용한 방음터널의 자연채광 성능평가에 관한 연구)

  • Kim, Oim-Gon;Choi, Jeong-Min;Park, Chang-Seob;Lee, Kyung-Hee
    • Journal of the Korean Solar Energy Society
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    • v.25 no.2
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    • pp.35-43
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    • 2005
  • This study aims to evaluate the natural lighting performance in the sound barrier tunnel. Therefore, to evaluate the daylighting performance, the combinations of 3 tunnel roof types which are flat-roof-type(type A), slope-roof-type(type B), arch-roof-type(type C) and 3 window types which are side-window-type(type 1), one-window-roof type(type 2), two-window-roof type(type 3) are evaluated by experimenting small scaled models. In this 9 cases of experiment, illuminance levels of each case are analyzed and evaluated. The conclusion of this study is that slope-roof-type(B) and arch-roof-type(C) is preferable to flat-roof-type(A) and one-window-roof-type(B) and two-window-roof-type(C) is preferable to side-window-type(A) for daylighting in the sound barrier tunnel.

Hull Form Optimization by Modification Function of Bell-shaped Distribution (종모양 분포 변환함수를 이용한 선형최적화 기법에 관한 연구)

  • Choi, Hee-Jong;Kim, Hee-Jung;Chun, Ho-Hwan;Jung, Kwang-Hyo
    • Journal of the Society of Naval Architects of Korea
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    • v.43 no.5 s.149
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    • pp.550-559
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    • 2006
  • A design procedure for a ship with minimum total resistance was developed using a numerical optimization method called SQP(Sequential Quadratic Programming) and a CFD technique based on the Rankine source panel method with the nonlinear free surface boundary conditions. During the whole optimization process the geometry of the hull shape was represented based on the NURBS(Non-uniform rational B-spline) technique and the modification of the hull shape was controlled using the Bell-shaped distribution function to keep the fairness of the hull shape before and after the hull modification. The numerical analysis was carried out using 4000TEU container ship in the towing tank facility installed in the Pusan national university to know the validity of the developed algorithm for this study. As the results of the numerical analysis it proved that the resistance of the optimized hull is conspicuously reduced in comparison with the original hull in a wave-making resistance point of view.