A parametric study on the evaluation of ductility demand distribution in multi-degree-of-freedom systems considering soil–structure interaction effects

Ganjavi, Behnoud; Hao, Hong

doi:10.1016/j.engstruct.2012.05.006

Cited by 42 publications

(17 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The other parameters, having less importance, may be set to some typical values for conventional buildings [19,27,30]. The third one controls the inelastic behavior of the structure.…”

Section: Key Parametersmentioning

confidence: 99%

“…A recent study by Ganjavi and Hao [27] indicates that using codespecified load pattern for soil-structure systems with severe SSI effect and high inelastic response does not lead to uniform (optimal) ductility demand distribution over the height of structures. A recent study by Ganjavi and Hao [27] indicates that using codespecified load pattern for soil-structure systems with severe SSI effect and high inelastic response does not lead to uniform (optimal) ductility demand distribution over the height of structures.…”

Section: Optimization Proceduresmentioning

confidence: 99%

See 1 more Smart Citation

Optimum lateral load pattern for seismic design of elastic shear‐buildings incorporating soil–structure interaction effects

Ganjavi

Hao

2012

Earthq Engng Struct Dyn

Self Cite

View full text Add to dashboard Cite

SUMMARY Recently, several new optimum loading patterns have been proposed by researchers for fixed‐base systems while their adequacy for soil–structure systems has not been evaluated yet. Through intensive dynamic analyses of multistory shear‐building models with soil–structure interaction subjected to a group of 21 artificial earthquakes adjusted to soft soil design spectrum, the adequacy of these optimum patterns is investigated. It is concluded that using these patterns the structures generally achieve near optimum performance in some range of periods. However, their efficiency reduces as soil flexibility increases especially when soil–structure interaction effects are significant. In the present paper, using the uniform distribution of damage over the height of structures, as the criterion, an optimization algorithm for seismic design of elastic soil–structure systems is developed. The effects of fundamental period, number of stories, earthquake excitation, soil flexibility, building aspect ratio, damping ratio and damping model on optimum distribution pattern are investigated. On the basis of 30,240 optimum load patterns derived from numerical simulations and nonlinear statistical regression analyses, a new lateral load pattern for elastic soil–structure systems is proposed. It is a function of the fundamental period of the structure, soil flexibility and structural slenderness ratio. It is shown that the seismic performance of such a structure is superior to those designed by code‐compliant or recently proposed patterns by researchers for fixed‐base structures. Using the proposed load pattern in this study, the designed structures experience up to 40% less structural weight as compared with the code‐compliant or optimum patterns developed based on fixed‐base structures. Copyright © 2012 John Wiley & Sons, Ltd.

show abstract

“…The other parameters, having less importance, may be set to some typical values for conventional buildings [19,27,30]. The third one controls the inelastic behavior of the structure.…”

Section: Key Parametersmentioning

confidence: 99%

Section: Optimization Proceduresmentioning

confidence: 99%

Optimum lateral load pattern for seismic design of elastic shear‐buildings incorporating soil–structure interaction effects

Ganjavi

Hao

2012

Earthq Engng Struct Dyn

Self Cite

View full text Add to dashboard Cite

show abstract

“…The kinematic interaction effect is not included assuming that the rigid foundation lies on the surface of the soil with no embedment. To model the frequency-dependent rotational spring and dashpot coefficients, an additional internal rotational degree of freedom, θ, is assigned to a polar mass moment of inertia, m  , and connected to the foundation mass with a zero-length element using a rotational dashpot [27][28][29]. Moreover, to modify the effect of soil incompressibility, an additional mass moment of inertia M   is added to the foundation when  is greater than 1/3 [34].…”

Section: Soil Modelmentioning

confidence: 99%

“…Compared to fixed-base systems, soil-structure systems possess longer periods and generally higher damping ratios due to the energy dissipation provided by hysteretic behaviour and wave radiation in the soil medium. Ganjavi and Hao [28] investigated the adequacy of IBC-2009 lateral loading patterns for seismic design of elastic and inelastic soil-structure systems through analyses of 7200 shear-buildings with SSI effects subjected to a group of 30 earthquakes recorded on alluvium and soft soils. They concluded that using the code-specified design load patterns leads to nearly uniform ductility demand distributions for structures having short periods and within the elastic range of response.…”

Section: Introductionmentioning

confidence: 99%

Optimum lateral load distribution for seismic design of nonlinear shear-buildings considering soil-structure interaction

Ganjavi

Hajirasouliha

Bolourchi

2016

Soil Dynamics and Earthquake Engineering

Self Cite

View full text Add to dashboard Cite

The lateral load distributions specified by seismic design provisions are primarily based on elastic behaviour of fixed-base structures without considering the effects of soil-structure-interaction (SSI).Consequently, such load patterns may not be suitable for seismic design of non-linear flexible-base structures. In this paper, a practical optimization technique is introduced to obtain optimum seismic design loads for non-linear shear-buildings on soft soils based on the concept of uniform damage distribution. SSI effects are taken into account by using the cone model. Over 30,000 optimum load patterns are obtained for 21 earthquake excitations recorded on soft soils to investigate the effects of fundamental period of the structure, number of stories, ductility demand, earthquake excitation, damping ratio, damping model, structural post yield behaviour, soil flexibility and structural aspect ratio on the optimum load patterns.The results indicate that the proposed optimum load patterns can significantly improve the seismic performance of flexible-base buildings on soft soils.

show abstract

“…In many codes (such as Mexico's Federal District Code MFDC-04 [1] and ASCE/SEI 7-05 [2]), the lateral load patterns along the height of building depend on the fundamental period and their masses (Ganjavi and Hao [3]). In these codes, the load pattern is obtained by elastic analysis under a fixed-base condition, neglecting the possible effects of soil-foundation flexibility.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Soil-Structure Interaction of Ductile Steel Frames in Soft Soils

2017

View full text Add to dashboard Cite

ABSTRACT:Results of static and dynamic nonlinear analysis of ductile steel frames of 8-and 12-stories buildings are discussed in this paper. The influence of dynamic soil-structure interaction in deformation demands, failure mechanism, ductility and overstrength capacities and maximum demands in columns were analyzed. For this purpose, buildings were designed and studied under three boundary conditions: (i) fixed-base (no Soil-Structure Interaction), (ii) pile foundation and (iii) mat foundation condition. The influence of the lateral stiffness was studied through the response of moment resisting frames (unbraced frames), 1-braced bay frames and 2-braced bays frames. Soil foundation dynamic stiffness (impedance function) is introduced by a set of springs in horizontal and rocking direction, which were computed from the dynamic behavior and properties of the soil-foundation system. It was found that fixed base model might not be a conservative representation of the response of buildings with flexible foundations, especially when a pile foundation system is considered.

show abstract

A parametric study on the evaluation of ductility demand distribution in multi-degree-of-freedom systems considering soil–structure interaction effects

Cited by 42 publications

References 32 publications

Optimum lateral load pattern for seismic design of elastic shear‐buildings incorporating soil–structure interaction effects

Optimum lateral load pattern for seismic design of elastic shear‐buildings incorporating soil–structure interaction effects

Optimum lateral load distribution for seismic design of nonlinear shear-buildings considering soil-structure interaction

Dynamic Soil-Structure Interaction of Ductile Steel Frames in Soft Soils

Contact Info

Product

Resources

About