• Title, Summary, Keyword: Displacement Limit

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An application of large displacement limit analysis to frame structures

  • Challamel, Noel
    • Structural Engineering and Mechanics
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    • v.33 no.2
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    • pp.159-177
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    • 2009
  • The aim of this paper is to give a rigorous framework for the interpretation of limit analysis results including large displacements. The presentation is oriented towards unidimensional media (beams) but two-dimensional (plates) or three-dimensional media are also concerned. A single-degree-of-freedom system is first considered: it shows the basic phenomena of large displacement limit analysis or second-order limit analysis. The results are compared to those of a continuous system and the differences between both systems are discussed. Theoretical results are obtained using the kinematical approach of limit analysis. An admissible load-displacement plane is then defined, according to the yield design theory. The methodology used is applied to frame structures. The presented results are nevertheless different from those already published in the literature, as the virtual displacement field can be distinguished from the displacement field at collapse. The simplicity of large displacement limit analysis makes it attractive for practical engineering applications. The load-displacement upper bound can be used for instance in the optimal design of steel frames in seismic areas.

Design charts for yield acceleration and seismic displacement of retaining walls with surcharge through limit analysis

  • Aminpoor, Mohamad Mahdi;Ghanbari, Ali
    • Structural Engineering and Mechanics
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    • v.52 no.6
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    • pp.1225-1256
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    • 2014
  • Calculating the seismic displacement of retaining walls has an important role in the optimum design of these structures. Also, studying the effect of surcharge is important for the calculation of active pressure as well as permanent displacements of the wall. In this regard, some researchers have investigated active pressure; but, unfortunately, there are few investigations on the seismic displacement of retaining walls with surcharge. In this research, using limit analysis and upper bound theorem, permanent seismic displacement of retaining walls with surcharge was analyzed for sliding and overturning failure mechanisms. Thus, a new formulation was presented for calculating yield acceleration, critical angle of failure wedge, and permanent displacement of retaining walls with surcharge. Also, effects of surcharge, its location and other factors such as height of the wall and internal friction angle of soil on the amount of seismic displacements were investigated. Finally, designing charts were presented for calculating yield acceleration coefficient and angle of failure wedge.

Development of design method using Limit Equilibrium Method applying to vertical excavation reinforcing by soil-nailing (쏘일네일 보강 연직굴착면의 한계 평형법을 이용한 설계기법 개발)

  • Lee, Seom-Beom;Lee, In;Yun, Bae-Sik;Kim, Hong-Taek
    • Journal of the Korea Construction Safety Engineering Association
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    • pp.56-62
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    • 2008
  • In order to apply the Limit Equilibrium Method generally used for the slope stability analysis to the vertical excavation walls reinforced by soil-nailing, in this study, the Limit Equilibrium Method for the temporary shoring facilities reinforced by soil-nailing was proposed, which is based on the stability for the horizontal displacement. In this study, the relation of the internal friction angles of the ground and the vertical excavation depths was arranged, which is satisfying the stability on the horizontal displacement by using the verification of the Limit Equilibrium Method. And then, the rational reinforcing length of soil-nailing was proposed for the critical areas. In addition, the modified safety ratio satisfying the stability on the horizontal displacement was proposed, when the Limit Equilibrium Method was applied to the vertical excavation walls reinforced by soil-nailing.

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A CLINICAL STUDY OF TEMPOROMANDIBULAR JOINT DISORDERS BY USING ARTHROGRAPHY (측두하악관절조영술을 이용한 측두하악관절장애의 임상적 연구)

  • Lee Seung-Hyun;Hwang Eui-Hwan;Lee Sang-Rae
    • Journal of Korean Academy of Oral and Maxillofacial Radiology
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    • v.28 no.1
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    • pp.155-169
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    • 1998
  • The purpose of this study was to prove the relationship between arthrographic and clinical features in temporomandibular joint disorders. In order to carry out this study, ninety-eight arthrographic examinations of temporomandibular joints were performed on eighty-two patients who had the temporomandibular joint disorders. As the arthrographic examination, the cases were classified in three groups, disk displacement with reduction, disk displacement without reduction, within normal limit. After this, the cases were clinically examined, and the results were compared and analyzed in each other group. The obtained results were as follows; 1. As the classification by arthrographic examination, three groups (disc displacement with reduction, disc displacement without reduction, within normal limit) were 41 %, 54%, 5% of total cases in this study, respectively. 2. The third decade(65%) was most frequent in this study. The average age of each group (disc displacement with reduction, disc displacement without reduction, within normal limit) was 24, 28, 21, and disc displacement without reduction group was higher than any other group. 3. In the chief complaint, pain was the most frequent in all three groups. Joint sound was also frequent in disc displacement with reduction group, but in disc displacement without reduction group, limitation of mouth opening was more frequent. 4. Of the various pain, the movement pain was most frequent ( 61 %) in this study. In joint sound, click(63%) was the most frequent in disc displacement with reduction group, but sound history(42%) and no sound (31 %) were more frequent in disc displacement without reduction group. 5. The average maximum opening of each group (disc displacement with reduction, disc displacement without reduction, within normal limit) was 44mm, 32.9mm, 44mm, and disc displacement without reduction group was less than any other group. 6. The masticatory disturbance of each group (disc displacement with reduction, disc displacement without reduction, within normal limit) was 53%, 79%, 40%, and the trauma history of each group was 50%, 40%,60%.

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An Analytical Study on the Relationship between Factor of Safety and Horizontal Displacement of Soil Nailed Walls (쏘일네일 보강벽체의 수평변위와 안전율과의 관계 분석연구)

  • Kim, Hongtaek;Lee, In
    • Journal of the Korean GEO-environmental Society
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    • v.12 no.2
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    • pp.45-53
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    • 2011
  • Soil nailing method was often designed by the slope stability analysis based on limit equilibrium. However, in the case of shorten length of nails, although the calculated factor of safety is within the design factor of safety, the horizontal displacement of soil nailed walls occurred above the allowable limit. In this study, relationship between the load and factor of safety, and relationship between the load and displacement ratio based on the test results were analysed. From the analysed results, the relationship between factor of safety and displacement ratio was estimated. For the mobilized horizontal displacement of the walls within the serviceability limit corresponding to the displacement of less than 0.3% displacement ratio, the calculated factor of safety by limit equilibrium analysis had to satisfy above 1.35. Also, although the minimum factor of safety is estimated above 1.35, the maximum horizontal displacement is often mobilized above 0.3% of excavation height. Therefore, it is necessary to perform the numerical analysis of soil nailed walls in the case of low shear strength or high excavation.

Changes in Selected Electrolyte Concentrations in Dairy Cowe with Abomasal Displacement (제사위전위증유우에 있어서 몇가지 혈청전해질 농도에 관한 조사연구)

  • Lee Sa-Kyun;Cheong Chang-Kook
    • Journal of Veterinary Clinics
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    • v.2 no.1
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    • pp.143-150
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    • 1985
  • The concentrations of serum calcium, inorganic phosphorus, sodium and potassium from 24 cows with left displacement of abomasum and 21 cows with right displacement of abomasum on pre and postoperation were determined. 1. The preoperative levels of serum calcium in left and right displacement of abomasum were below normal and returned to normal levels postoperatively. 2. The preoperative levels of serum inorganic phosphorus in left and right displacement of abomasum showed slight increase preoperatively and consistent slight rise postoperatively. 3. The preoperative levels of serum sodium in left and right displacement of abomasum were slightly below normal and maintained low levels postoperatively. 4. The preoperative levels of serum patassium in left and right displacement of abomasum were low normal limit and increased to upper normal limit postoperatively.

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Characterization and uncertainty of uplift load-displacement behaviour of belled piers

  • Lu, Xian-long;Qian, Zeng-zhen;Zheng, Wei-feng;Yang, Wen-zhi
    • Geomechanics and Engineering
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    • v.11 no.2
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    • pp.211-234
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    • 2016
  • A total of 99 full-scale field load tests at 22 sites were compiled for this study to elucidate several issues related to the load-displacement behaviour of belled piers under axial uplift loading, including (1) interpretation criteria to define various elastic, inelastic, and "failure" states for each load test from the load-displacement curve; (2) generalized correlations among these states and determinations to the predicted ultimate uplift resistances; (3) uncertainty in the resistance model factor statistics required for reliability-based ultimate limit state (ULS) design; (4) uncertainty associated with the normalized load-displacement curves and the resulting model factor statistics required for reliability-based serviceability limit state (SLS) design; and (5) variations of the combined ULS and SLS model factor statistics for reliability-based limit state designs. The approaches discussed in this study are practical and grounded realistically on the load tests of belled piers with minimal assumptions. The results on the characterization and uncertainty of uplift load-displacement behaviour of belled piers could be served as to extend the early contributions for reliability-based ULS and SLS designs.

A Study on Development of Structural Health Monitoring System for Steel Beams Using Strain Gauges (변형률계를 이용한 강재보의 건전도 평가 시스템 개발에 관한 연구)

  • Hahn, Hyun Gyu;Ahn, Hyung Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.1
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    • pp.99-109
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    • 2012
  • This study aimed to develop a Structural Health Monitoring System for steel beams in the manner of suggesting and verifying a theoretical formula for displacement estimation using strain gauges, and estimating the loading points and magnitude. According to the results of this study, it was found that when a load of 160kN (56% of the yield load) was applied, the error rate of the deflection obtained with a strain gauge at the point of maximum deflection compared to the deflection measured with a displacement meter was within 2%, and that the estimates of the magnitude and points of load application also showed the error rate of not more than 1%. This suggests that the displacement and load of steel beams can be measured with strain gauges and further, it will enable more cost-effective sensor designing without displacement meter or load cell. The Structural Health Monitoring System program implemented in Lab VIEW gave graded warnings whenever the measured data exceeds the specified range (strength limit state, serviceability limit state, yield strain), and both the serviceability limit state and strength limit state could be simultaneously monitored with strain gauge alone.

The MIN-N family of pure-displacement, triangular, Mindlin plate elements

  • Liu, Y. Jane;Riggs, H.R.
    • Structural Engineering and Mechanics
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    • v.19 no.3
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    • pp.297-320
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    • 2005
  • In recent years the pure displacement formulation for plate elements has not been as popular as other formulations. We revisit the pure displacement formulation for shear-deformable plate elements and propose a family of N-node, displacement-compatible, fully-integrated, pure-displacement, triangular, Mindlin plate elements, MIN-N. The development has been motivated by the relative simplicity of the pure displacement formulation and by the success of the existing 3-node plate element, MIN3. The formulation of MIN3 is generalized to obtain the MIN-N family, which possesses complete, fully compatible kinematic fields, in which the interpolation functions for transverse displacement are one degree higher than those for rotations. General element-level formulas for the thin-limit Kirchhoff constraints are developed. The 6-node, 18 degree-of-freedom element MIN6, with cubic displacement and quadratic rotations, is implemented and tested extensively. Numerical results show that MIN6 exhibits good performance for both static and dynamic analyses in the linear, elastic regime. The results illustrate that the fully-integrated MIN6 element has excellent performance in the thin limit, even for coarse meshes, and that it does not require shear relaxation.

The Displacement Limit at the End of an Approach Slab for a Railway Bridge with Ballastless Track (콘크리트궤도 부설 교량의 접속슬래브 단부 처짐한도에 관한 연구)

  • Choi, Jin-Yu;Yang, Shin-Chu
    • Journal of the Korean Society for Railway
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    • v.11 no.2
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    • pp.195-202
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    • 2008
  • The transition area between a bridge and an earthwork is one of the weakest area of track because of the track geometry deterioration caused unequal settlement of backfill of abutment. In case of a ballastless track, the approach slab could be installed to prevent such a phenomenon. But, if there is occurred the inclined displacement on the approach slab by a settlement of the foundation or formation, the track is also under the inclined displacement. And this defect causes reducing the running stability of a vehicle, the riding comfort of passengers, and increasing the track deteriorations by excessive impact force acting on the track. In this study, parametric studies were performed to investigate the displacement limit on the approach slab to avoid such problems. The length and the amount of unequal settlement of approach slab were adopted as parameter for numerical analysis considering vehicle-track interaction. Car body accelerations, variations of wheel force, stresses in rail, and uplift forces induced on fastener clip were investigated. From the result, resonable settlement limit on the end of an approach slab according to slab length was suggested.