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If utilized, the energy dissipative capability of seismically loaded shallow foundations due to inelastic behavior can result in more economic design, provided the consequences, such as excessive deformations are accounted for. In this article, a Beam‐on‐Nonlinear‐Winkler‐Foundation (BNWF) model is used to assess the performance of shearwall‐foundation systems with different attributes, when subjected to ground motions of varied hazard levels. The numerical study indicates that the force and drift demands to the shearwall reduce significantly, when nonlinear foundation behavior is realized, while permanent settlement is well below the permissible limit. These results support the concept of shallow foundation capacity mobilization in future design. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Focusing on low-rise steel buildings supported by shallow isolated foundations on dense silty sand, this study demonstrates the effect of uncertainty in soil parameters on seismic response of structures. Considering a set of 20 ground motions representing 10% in 50 years hazard level and concentrating on peak base moment, base shear and interstory drift as the demand variables of interest, it is found that uncertainty in soil parameters may result in significant response variability of the structures, especially when vertical factor of safety is low and the structure is relatively stiff. Uncertainty in friction angle results in significant variability of the peak base moment and base shear, while peak interstory drift ratio is found to be virtually unaffected by uncertainty in soil parameters. It is also found that a linear soil–structure-interaction (SSI) model will not be able to predict such response variability under these set of ground motions. 相似文献
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The nonlinear behavior of a soil-foundation system may alter the seismic response of a structure by providing additional flexibility to the system and dissipating hysteretic energy at the soil-foundation interface. However, the current design practice is still reluctant to consider the nonlinearity of the soil-foundation system, primarily due to lack of reliable modeling techniques. This study is motivated towards evaluating the effect of nonlinear soil-structure interaction (SSI) on the seismic responses of low-rise steel moment resisting frame (SMRF) structures. In order to achieve this, a Winkler-based approach is adopted, where the soil beneath the foundation is assumed to be a system of closely-spaced, independent, nonlinear spring elements. Static pushover analysis and nonlinear dynamic analyses are performed on a 3-story SMRF building and the performance of the structure is evaluated through a variety of force and displacement demand parameters. It is observed that incorporation of nonlinear SSI leads to an increase in story displacement demand and a significant reduction in base moment, base shear and inter-story drift demands, indicating the importance of its consideration towards achieving an economic, yet safe seismic design. 相似文献
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Probabilistic and spatial liquefaction analysis using CPT data: a case study for Alameda County site
Soil liquefaction is one of the major concerns causing damage to the structures in saturated sand deposits during earthquakes. Simplified methods for the assessment of liquefaction potential rely on the limit states that are generally established with built-in conservatism and a great deal of subjectivity. Well-known SPT- and CPT-based methods are widely used in the design practice for this purpose due to their simplicity and reasonable predictive capability. However, these methods do not account for various sources of uncertainties explicitly. Moreover, evaluations are made only at the locations of test results and are generalized for the whole region, which may not give accurate results where spatial variation of soil properties is significant. The present study focuses on the probabilistic evaluation of liquefaction potential of Alameda County site, California, considering spatial variation of soil indices related to CPT soundings. A stochastic soil model is adopted for this purpose using random field theory and principles of geostatistics by developing 2D exponential correlation functions. It has been observed that the probability of liquefaction is significantly underestimated as much as 34 %, if the spatial dependence of soil indices is not considered. Further, the effect of spatial variation is more prominent in low-level earthquakes compared to the high-level earthquakes, showing a 41.5 % deviation for magnitude 8.1 and a 60.5 % deviation for magnitude 5.0 earthquake at a depth of 10 m. 相似文献
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