• Title/Summary/Keyword: foundation slab

Search Result 86, Processing Time 0.039 seconds

Numerical Analysis for High-rise Building Foundation and Further Investigations on Piled Raft Design

  • Won, Jinoh;Lee, Jin Hyung;Cho, Chunwhan
    • International Journal of High-Rise Buildings
    • /
    • v.4 no.4
    • /
    • pp.271-281
    • /
    • 2015
  • This paper introduces detailed three-dimensional numerical analyses on a bored pile foundation for a high-rise building. A static load test was performed on a test pile and a numerical model of a single pile, which was calibrated by comparing it with the test result. The detailed numerical analysis was then conducted on the entire high-rise building foundation. Further study focused on soil pressures under the base slab of a piled raft foundation. Total seven cases with different pile numbers and raft-soil contact conditions were investigated. The design criteria of a foundation, especially settlement requirement were satisfied even for the cases with fewer piles under considerable soil pressure beneath the base slab. The bending moment for the structural design of the base slab was reduced by incorporating soil pressures beneath the base slab along with bored piles. Through the comparative studies, it was found that a more efficient design can be achieved by considering the soil pressure beneath the slab.

Dynamic response of pile foundations with flexible slabs

  • Kaynia, Amir M.
    • Earthquakes and Structures
    • /
    • v.3 no.3_4
    • /
    • pp.495-506
    • /
    • 2012
  • An elasto-dynamic model for pile-soil-pile interaction together with a simple plate model is used in this study to assess the effect of flexible foundation slabs on the dynamic response of pile groups. To this end, different pile configurations with various slab thicknessesare considered in two soil media with low and high elastic moduli. The analyses include dynamic impedances and seismic responses of pile-group foundations. The presented results indicate that the stiffness and damping of pile foundations increase with thickness of the foundation slab; however, the results approach those for rigid slab as the slab thickness approaches twice the pile diameter for the cases considered in this study. The results also reveal that pile foundations with flexible slabs may amplify the earthquake motions by as much as 10 percent in the low to intermediate frequency ranges.

Concrete Slab with Partial Supports due to its Deformation (자체변형에 의한 부분지지조건을 갖는 콘크리트 슬래브)

  • 한승환;유태석
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 1999.10a
    • /
    • pp.429-432
    • /
    • 1999
  • The concrete slab on the foundation may have curling and warping deformations due to moisture and temperature gradient of its section. These deformations may change the support conditions of concrete slabs, and cause higher level of stresses than expected. This study was performed to verify the effect of partial support condition of concrete slab on the foundation due to its deformations and to develop the useful analytic method for describing these phenomenons. The partial support condition verified by FWD test results, and it was concluded that the gap model could be useful in analysing the concrete slab with partial support conditions.

  • PDF

Study on Seismic Response of Wall-Slab Apartment Building Sturucture Considering the Stiffnesses of a Foundation-Soil System (기초지반강성을 고려한 벽식구조 아파트의 지진응답에 관한 연구)

  • 김지원
    • Proceedings of the Earthquake Engineering Society of Korea Conference
    • /
    • 2000.10a
    • /
    • pp.167-175
    • /
    • 2000
  • Seismic analyses of structures can`t be performed without considering the effect of soil-structure interaction and seismic responses of a structure taking into account the stiffnesses of a foundation-soil system show a significant difference from those with a rigid base. However, current seismic analyses of apartment building structures were carried out assuming a rigid base and ignoring the characteristics of a foundation and the properties of the underlying soil. In this study, seismic analyses of apartment buildings of a particular wall-slab structural type were carried out comparing seismic response spectra of a flexible base with those of a rigid base and UBC-97. Wall-slab type low-rise or mid-height apartment buildings built on the deep soil layer showed a rigid body motion with the reduced seismic responses due to the base isolation effect, indicating that it is too safe but uneconomical to utilize the design spectra of UBC-97 for the seismic analysis of a wall-slab type apartment buildings due to the too conservative design.

  • PDF

A Study on Prediction of Moment Developed in Bottom of Foundations between Pile and Heterogeneous Soils (말뚝기초와 이질지반 경계부 기초저판에서의 발생모멘트 예측에 관한 연구)

  • Lim, Hae-Sik;Park, Yong-Boo
    • Land and Housing Review
    • /
    • v.2 no.3
    • /
    • pp.277-285
    • /
    • 2011
  • To reinforce bearing capacity-changed section or different foundation in the same building, empirical or simple tools have been used. To solve this problem, an analytical solution which can evaluate and reinforce the stability of foundation is introduced. To suggest a clue for the problems, current foundation reinforcing method is studied through recent literature studies and the structural analyses of foundation slab are performed on the pile foundation of 49$m^2$, 59$m^2$ and 84$m^2$ I type apartments in 15 story building. The analyses are conducted with SAP 2000, a computer program for ordinary structural analysis. To predict the moments of slab by ground non-uniformity, the structural analysis results for the foundation slab of 3 types 15 story apartment buildings in 49$m^2$, 59$m^2$ and 84$m^2$ I type on non-uniformity ground are shown in the diagrams.

Numerical Analysis of Curling Behavior of Prestressed Approach Slab Subjected to Environmental Loads (환경하중에 의한 교량 프리스트레스 접속슬래프의 컬링 거동 수치 해석적 분석)

  • Park, Hee-Beom;Eum, In-Sub;Kim, Seong-Min;Rhee, Suk-Keun
    • International Journal of Highway Engineering
    • /
    • v.13 no.3
    • /
    • pp.7-14
    • /
    • 2011
  • The numerical analyses were performed to investigate the curling behavior of the post-tensioned prestressed concrete approach slab (PTAS) under environmental loads. A technique to include properly the boundary conditions of one end of PTAS that was connected to the bridge abutment using hinges was proposed for the numerical model. The applicability of a simplified model not having hunches was also investigated. By using the developed models, the curling behavior of PTAS was analyzed when the foundation settlement occurred. The analysis results showed that the maximum tensile stress obtained from the simplified model involving a simplified hinge connection was very closed to that obtained from a rigorous model. When the slab curled up, the maximum tensile stress occurred in the model including no foundation settlement, but when the slab curled down, the maximum stress occurred in the model including partial settlement of the foundation. Therefore, the design of PTAS should be performed considering those maximum tensile stresses.

Effect of Horizontal Resistance at Slab Bottom on Behavior of Concrete Slabs-on-Grade under Vertical Loads (지반위에 놓인 콘크리트 슬래브의 수직하중에 대한 슬래브 하부의 수평 저항의 영향 분석)

  • Shim, Jae-Soo;Kim, Seong-Min
    • International Journal of Highway Engineering
    • /
    • v.7 no.4 s.26
    • /
    • pp.141-150
    • /
    • 2005
  • The behavior of the concrete slabs-on-grade considering the horizontal resistance at the slab bottom, which exists due to the shear resistance of the foundation and the friction between the slab and the foundation, has been investigated when the slabs-on-grade are subjected to the vertical load. Analytical formulations have been developed to include the effect of the horizontal resistance at the slab bottom, and the solutions have been obtained in the transformed field domain using the Fourier transform. Finite element formulations have also been developed using the plate bending elements and the flat shell elements. The solutions from the analytical and numerical models have been compared and showed very good agreement. The sensitivity of the horizontal resistance to the stresses of the concrete slab has been investigated with various values of the slab thickness, elastic modulus, and vertical stiffness of the foundation. The analysis results show that the horizontal resistance at the plate bottom can significantly affect the stresses of the slab.

  • PDF

Vibration Analysis of Orthortopic Composite Plate According to Elastic Reaction Effect (탄성반력의 영향에 따른 직교 이방성 복합판의 고유 진동 해석)

  • Jung, Young-Hwa;Shim, Do-Sik;Kim, Kyoung-Jin;Lee, Se-Jin
    • Journal of Industrial Technology
    • /
    • v.17
    • /
    • pp.199-204
    • /
    • 1997
  • In this paper, the result of application of vibration method to the orthotropic plates with free edges supported on elastic foundation and with a pair of opposite edges under axial forces is presented. Such plates represent the concrete highway slab and hybrid composite pavement of bridges. The reinforced concrete slab can be assumed as a special orthotropic plate, as a close approximation. The highway slab is supported on elastic foundation, with free boundaries. Sometimes, the pair of edges perpendicular to the traffic direction may be subject to the axial forces. The plate is subject to the concentrated load/loads, in the form of traffic loads, or the test equipments. Finite difference method is used to obtain the deflection influence surfaces needed for vibration analysis. The influence of the modulus of the foundation, the aspect ratio of the plate, and the magnitudes of the axial forces and the concentrated attached mass on the plate, under the natural frequency is thoroughly studied.

  • PDF

Analysis Models of Concrete Slabs-on-Grade Considering Horizontal Resistance at Slab Bottom and Behavior under Thermal Loads (슬래브 하부 수평저항을 고려한 지반위의 콘크리트 슬래브 해석 모델 및 온도하중에 의한 거동 분석)

  • Kim Seong-Min;An Zu-Og
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.19 no.3 s.73
    • /
    • pp.271-282
    • /
    • 2006
  • The behavior of the concrete slabs on grade considering the horizontal resistance at the slab bottom, which exists due to the shear resistance of the foundation and the friction between the slab and the foundation, has been investigated when the slabs-on-grade are subjected to the thermal load. Analytical formulations have been developed to include the effect of the horizontal resistance at the slab bottom employing the thin plate on an elastic foundation that is widely used for the analysis of concrete slabs-on-grade and rigid pavement systems. Finite element formulations have then been developed using the plate bending elements and the flat shell elements. The solutions from the analytical and numerical models have been compared and showed very good agreement. The sensitivity of the horizontal resistance to the stresses of the concrete slab has been investigated with various values of the slab thickness, elastic modulus, and vortical stiffness of the foundation when subjected to the temperature gradient between the top and bottom of the slab and the uniform temperature drop throughout the slab depth. The analysis results show that the horizontal resistance at the plate bottom can significantly affect the stresses of the slab when the thermal loads are applied.

Vibration analysis of special orthortopic plate with free edges supported on elastic foundation and with a pair of opposite edges under axial forces (탄성기초에 지지되고 양단 축하중을 받는 특별직교 이방성 판의 진동해석)

  • 김덕현;원치문;정경일;박정호
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 1998.04a
    • /
    • pp.327-334
    • /
    • 1998
  • A method of calculating the natural frequency corresponding to the first mode of vibration of beams and toll.or structures, with irregular cross sections and with arbitrary boundary conditions was developed and reported by Kim, D. H. in 1974. In this paper, the result of application of this method to the special orthotropic plates with free edges supported on elastic foundation and with a pair of opposite edges under axial forces is presented. Such plates represent the concrete highway slab and hybrid composite pavement of bridges. The reinforced concrete slab can be assumed as a special orthotropic plate, as a close approximation. The highway slab is supported on elastic foundation, with free boundaries. Sometimes, the pair of edges perpendicular to the traffic direction may be subject to the axial forces. The plate is subject to the concentrated load/loads, in the form of traffic loads, or the test equipments. Any method nay be used to obtain the deflection influence surfaces needed for this vibration analysis. Finite difference method is used for this purpose, in this paper. The influence of the modulus of the foundation, the aspect ratio of the plate, and the magnitudes of the axial forces and the concentrated attached mass on the plate, on the natural frequency is thoroughly studied.

  • PDF