• Title/Summary/Keyword: Axial skeleton

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An analytical model for PVC-FRP confined reinforced concrete columns under low cyclic loading

  • Fang, Yuan;Yu, Feng;Chen, Anchun;Wang, Shilong;Xu, Guoshi
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.179-196
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    • 2021
  • Experimental investigations on the seismic behaviors of the PVC-FRP Confined Reinforced Concrete (PFCRC) columns under low cyclic loading are carried out and two variable parameters including CFRP strips spacing and axial compression ratio are considered. The PFCRC column finally fails by bending and is characterized by the crushing of concrete and yielding of the longitudinal reinforcement, and the column with a high axial compression ratio is also accompanied by the cracking of the PVC tube and the fracture of CFRP strips. The hysteretic curves and skeleton curves of the columns are obtained from the experimental data. With the increase of axial compression ratio, the stiffness degradation rate accelerates and the ductility decreases. With the decrease of CFRP strips spacing, the unloading sections of the skeleton curves become steep and the ductility reduces significantly. On the basis of fiber model method, a numerical analysis approach for predicting the skeleton curves of the PFCRC columns is developed. Additionally, a simplified skeleton curve including the elastic stage, strengthening stage and unloading stage is suggested depending on the geometric drawing method. Moreover, the loading and unloading rules of the PFCRC columns are revealed by analyzing the features of the skeleton curves. The quantitative expressions that are used to predict the unloading stiffness of the specimens in each stage are proposed. Eventually, an analytical model for the PFCRC columns under low cyclic loading is established and it agrees well with test data.

A Study on the Behavior Properties of Residential-Commercial Building by Pushover Analysis (정적탄소성해석에 의한 복합구조물의 거동특성에 관한 연구)

  • 강병두;전대한;김재웅
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.10a
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    • pp.209-216
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    • 2000
  • The purpose of this study is to investigate elasto-plastic behaviour and estimate ultimate resistance capacity of the residential-commercial building subjected to lateral force along the height of structure. Four types of residential-commercial building are chosen as analytical models and investigated by pushover analysis. Pushover analysis estimates initial elastic stiffness, post-yielding stiffness, and plastic hinges on each story of structures through three-dimensional nonlinear analysis program CANNY-99. Skeleton curve of bending stiffness model is bilinear, shear stiffness model is trilinear, and axial stiffness model is elastic. Skeleton curve of axial stiffness model has the axial compression and tension stiffness of reinforced concrete members. This study presents the change of inter story drift, story stiffness and hinge of story and member.

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Seismic performances of steel reinforced concrete bridge piers

  • Deng, Jiangdong;Liu, Airong;Yu, Qicai;Peng, Guoxing
    • Steel and Composite Structures
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    • v.21 no.3
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    • pp.661-677
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    • 2016
  • The quasi static test of the steel reinforced concrete (SRC) bridge piers and rigid frame arch bridge structure with SRC piers was conducted in the laboratory, and the seismic performance of SRC piers was compared with that of reinforced concrete (RC) bridge piers. In the test, the failure process, the failure mechanism, hysteretic curves, skeleton curves, ductility coefficient, stiffness degradation curves and the energy dissipation curves were analyzed. According to the $M-{\Phi}$ relationship of fiber section, the three-wire type theoretical skeleton curve of the lateral force and the pier top displacement was proposed, and the theoretical skeleton curves are well consistent with the experimental curves. Based on the theoretical model, the effects of the concrete strength, axial compression ratio, slenderness ratio, reinforcement ratio, and the stiffness ratio of arch to pier on the skeleton curve were analyzed.

Metastatic Clear Cell Sarcoma of the Kidney in a Child's Hand Bone - A Case Report - (소아의 수부골에 전이된 신장의 투명세포육종 -1례 보고-)

  • Shim, Jong-Sup;Kim, Jee-Hyoung;Suh, Yeon-Lim
    • The Journal of the Korean bone and joint tumor society
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    • v.4 no.2
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    • pp.94-98
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    • 1998
  • Clear cell sarcoma of the kidney (CCSK) is a rare malignant tumor of the renal origin in childhood, distinguished from Wilms tumor by its pathologic and clinical features. Bone metastasis is one of the characteristic clinical features. The common site of metastasis of the clear cell Sarcoma of the kidney is axial skeleton including skull, spines, ribs and femur. A cases of clear cell Sarcoma of the kidney presented to us, which solely metastasized to the hand bones without metastasizing to any other tissues including axial skeleton. We report this case with review of literatures.

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Experimental and numerical analysis of seismic behaviour for recycled aggregate concrete filled circular steel tube frames

  • Xianggang Zhang;Gaoqiang Zhou;Xuyan Liu;Yuhui Fan;Ercong Meng;Junna Yang;Yajun Huang
    • Computers and Concrete
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    • v.31 no.6
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    • pp.537-543
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    • 2023
  • To study the seismic behavior of recycled aggregate concrete filled circular steel tube (RACFCST) frames, the seismic behavior experiment of RACFCST frame was carried out to measure the hysteresis curve, skeleton curve and other seismic behavior indexes. Moreover, based on the experimental study, a feasible numerical analysis model was established to analyze the finite element parameters of 8 RACFCST frame specimens, and the influence of different variation parameters on the seismic behavior index for RACFCST frame was revealed. The results showed that the skeleton curve of specimens under different axial compression ratios were divided into three stages: elastic stage, elastic-plastic stage and descending stage, and the descending stage was relatively stable, indicating that the specimen had stronger deformation capacity in the descending stage. With the increase of axial compression ratio, the peak bearing capacity of all specimens reduced gradually, and the reduction was less than 5%. With the decrease of beam-column linear stiffness ratio, the peak bearing capacity decreased gradually. With the decrease of yield bending moment ratio of beam-column, the peak bearing capacity decreased gradually, and the decreasing rate of peak bearing capacity gradually accelerated. In addition, compared with the axial compression ratio, the beam-column linear stiffness ratio and the yield bending moment ratio of beam-column had a more significant influence on the peak bearing capacity of RACFCST frame.

Investigating the load-displacement restorative force model for steel slag self-stressing concrete-filled circular steel tubular columns

  • Feng Yu;Bo Xu;Chi Yao;Alei Dong;Yuan Fang
    • Steel and Composite Structures
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    • v.49 no.6
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    • pp.615-631
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    • 2023
  • To investigate the seismic behavior of steel slag self-stressing concrete-filled circular steel tubular (SSSCFCST) columns, 14 specimens were designed, namely, 10 SSSCFCST columns and four ordinary steel slag (SS) concrete (SSC)-filled circular steel tubular (SSCFCST) columns. Comparative tests were conducted under low reversed cyclic loading considering various parameters, such as the axial compression ratio, diameter-thickness ratio, shear-span ratio, and expansion ratio of SSC. The failure process of the specimens was observed, and hysteretic and skeleton curves were obtained. Next, the influence of these parameters on the hysteretic behavior of the SSSCFCST columns was analyzed. The self stress of SS considerably increased the bearing capacity and ductility of the specimens. Results indicated that specimens with a shear-span ratio of 1.83 exhibited compression bending failure, whereas those with shear-span ratios of 0.91 or 1.37 exhibited drum-shaped cracking failure. However, shear-bond failure occurred in the nonloading direction. The stiffness of the falling section of the specimens decreased with increasing shear-span ratio. The hysteretic curves exhibited a weak pinch phenomenon, and their shapes evolved from a full shuttle shape to a bow shape during loading. The skeleton curves of the specimens were nearly complete, progressing through elastic, elastoplastic, and plastic stages. Based on the experimental study and considering the effects of the SSC expansion rate, shear-span ratio, diameter-thickness ratio, and axial compression ratio on the seismic behavior, a peak displacement coefficient of 0.91 was introduced through regression analysis. A simplified method for calculating load-displacement skeleton curves was proposed and loading and unloading rules for SSSCFCST columns were provided. The load-displacement restorative force model of the specimens was established. These findings can serve as a guide for further research and practical application of SSSCFCST columns.

[ $45^{\circ}$ ] OBLIQUE CEPHALOMETRIC ANALYSIS OF MESIODISTAL AXIAL INCLINATION IN NORMAL OCCLUSION (정상교합자의 치축경사도에 관한 $45^{\circ}$ 측모두부방사선 계측학적 연구)

  • Kim, Kyung-Ho;Park, Young-Chel
    • The korean journal of orthodontics
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    • v.18 no.1 s.25
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    • pp.65-78
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    • 1988
  • The development of good arch form, the orientation of the dentition with relation to the craniofacial skeleton and the establishment of correct relationship of axial inclination of upper and lower teeth are required in normal occlusion, but different teeth present different degrees of axial inclination. The purpose of this study was to investigate the axial inclination of upper and lower teeth by analyzing $45^{\circ}$ oblique and $90^{\circ}$ cephalometric roentgenograms of 35 Korean males and 34 females with normal occlusion. The obtained results were as follows: 1. Mean and standard deviation of mesiodistal axial inclination of upper and lower teeth related to palatal plane and occlusal plane were obtained. 2. Mesiodistal axial inclination of upper first premolar was nearly perpendicular to palatal plane, and the axis of lower first premolar was nearly perpendicular to occlusal plane. 3. There was no difference in the mesiodistal axial inclination of anteriorly positioned teeth between the three groups: third molar eruption into good alignment (Group 1), third molar impaction or partial eruption (Group 2), third molar agenesis (Group 3). 4. There were low correlationships only between the axial inclination of central incisor and the mesiodistal axial inclination of canine and first premolar, but no correlationships between central incisor and posterior teeth behind first premolar.

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IMMEDIATE RECONSTRUCTION USING VERTICAL RAMUS OSTEOTOMY AND BONE SLIDNG AFTER CONDYLECTOMY DUE TO OSTEOCHONDROMA: A CASE REPORT (골연골종으로 인한 과두절제 후 하악지 수직 골절단술 및 bone sliding을 통한 즉시 재건: 증례보고)

  • Jang, Ji-Young;Oh, Jae-Kyung;Cha, Du-Won;Baek, Sang-Heum
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.29 no.3
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    • pp.233-240
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    • 2007
  • Osteochondroma is a common benign tumor of the axial skeleton, especially the distal metaphysis of the femur and proximal metaphysis of the tibia. However, it occurred rarely on the facial skeleton. The coronoid and condylar processes have been considered to be the most common sites of occurrence for osteochondroma of the facial skeleton. The first treatment of osteochondroma is condylectomy, whereas extirpation was done by excision with condyle salvage. Condylectomy presents decrease of vertical dimension, jaw deviation, malocclusion. So, reconstruction is need. Methods of reconstruction are as follows: no reconstruction, condyloplasty, discectomy, costochondral graft, discplication or coronoidectomy, eminoplasty, alloplastic spacer placement, Le Fort I level maxillary osteotomy, extraoral and intraoral vertical ramus osteotomy. This is a case report of a 28-year old woman who had facial asymmetry, malocclusion and temporomandibular joint pain. We obtained moderate functional and cosmetic results with surgical removal of the osteochondroma by condylectomy and concomitant reconstruction of condyle by vertical ramus osteotomy with sliding technique.

An Effects of $CO_2$ Addition on Flame Structure in a Non-premixed Counterflow Flame (비예혼합 대향류 화염에서 $CO_2$ 첨가가 화염 구조에 미치는 영향 연구)

  • Lee, Kee-Man
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.166-173
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    • 2007
  • A numerical study was conducted to have the effect of $CO_2$ addition to fuel on the chemical reaction mechanism with the change of the initial concentration of $CO_2$ and the axial velocity gradient. From this study, it was found that there were two serious effects of $CO_2$ addition on a non-premixed flame ; a diluent effect by the reactive species reduction and chemical effect of the breakdown of $CO_2$ by the third-body collision and thermal dissociation. Especially, the chemical effect was serious at the lower velocity gradient of the axial flow. It was certain that the mole fraction profile of $CO_2$ was deflected and CO was increased with the initial concentration of $CO_2$. It was also ascertained that the breakdown of $CO_2$ would cause the increasing of CO mole fraction at the reaction region. It was also found that the addition of $CO_2$ did not alter the basic skeleton of $H_2-O_2$ reaction mechanism, but contributed to the formation and destruction of hydrocarbon products such as HCO. The conversion of CO was also suppressed and $CO_2$ played a role of a dilution in the reaction zone at the higher axial velocity gradient.

Seismic behavior of Q690 circular HCFTST columns under constant axial loading and reversed cyclic lateral loading

  • Wang, Jiantao;Sun, Qing
    • Steel and Composite Structures
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    • v.32 no.2
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    • pp.199-212
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    • 2019
  • This paper presents an investigation on seismic behavior of out-of-code Q690 circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns made up of high-strength (HS) steel tubes (yield strength $f_y{\geq}690MPa$). Eight Q690 circular HCFTST columns with various diameter-to-thickness (D/t) ratios, concrete cylinder compressive strengths ($f_c$) and axial compression ratios (n) were tested under the constant axial loading and reversed cyclic lateral loading. The obtained lateral load-displacement hysteretic curves, energy dissipation, skeleton curves and ductility, and stiffness degradation were analyzed in detail to reflect the influences of tested parameters. Subsequently, a simplified shear strength model was derived and validated by the test results. Finally, a finite element analysis (FEA) model incorporating a stress triaxiality dependent fracture criterion was established to simulate the seismic behavior. The systematic investigation indicates the following: compared to the D/t ratio and axial compression ratio, improving the concrete compressive strength (e.g., the HS thin-walled steel tube filled with HS concrete) had a slight influence on the ductility but an obvious enhancement of energy dissipation and peak load; the simplified shear strength model based on truss mechanism accurately predicted the shear-resisting capacity; and the established FEA model incorporating steel fracture criterion simulated well the seismic behavior (e.g., hysteretic curve, local buckling and fracture), which can be applied to the seismic analysis and design of Q690 circular HCFTST columns.