The Experts below are selected from a list of 354 Experts worldwide ranked by ideXlab platform

Hamdy Abouelfath - One of the best experts on this subject based on the ideXlab platform.

  • upgrading the seismic capacity of existing rc buildings using buckling restrained braces
    alexandria engineering journal, 2017
    Co-Authors: Hamdy Abouelfath, Mostafa Ramadan, Fozeya Omar Alkanai
    Abstract:

    Abstract Many existing RC buildings do not meet the lateral strength requirements of current seismic codes and are vulnerable to significant damage or collapse in the event of future earthquakes. In the past few decades, buckling-restrained braces have become increasingly popular as a lateral force resisting system because of their capability of improving the strength, the stiffness and the energy absorbing capacity of structures. This study evaluates the seismic upgrading of a 6-story RC-building using single diagonal buckling restrained braces. Seismic evaluation in this study has been carried out by Static Pushover Analysis and time history earthquake Analysis. Ten ground motions with different PGA levels are used in the Analysis. The mean plus one standard deviation values of the roof-drift ratio, the maximum story drift ratio, the brace ductility factors and the member strain responses are used as the basis for the seismic performance evaluations. The results obtained in this study indicate that strengthening of RC buildings with buckling restrained braces is an efficient technique as it significantly increases the PGA capacity of the RC buildings. The results also indicate the increase in the PGA capacity of the RC building with the increase in the amount of the braces.

  • response based damage assessment of structures
    Earthquake Engineering & Structural Dynamics, 1999
    Co-Authors: Ahmed Ghobarah, Hamdy Abouelfath, Ashraf Biddah
    Abstract:

    The structure's ability to survive an earthquake may be measured in terms of the expected state of damage of the structure after the earthquake. Damage may be quantified by using any of several damage indices defined as functions whose values can be related to particular structural damage states. A number of available response-based damage indices are discussed and critically evaluated for their applicability in seismic damage evaluation. A new rational approach for damage assessment is presented which provides a measure of the physical response characteristics of the structure and is better suited for non-linear structural Analysis. A practical method based on the Static Pushover Analysis is proposed to estimate the expected damage to structures when subjected to earthquakes of different intensities. Results of the Analysis of ductile and non-ductile reinforced concrete buildings show that the proposed procedure for damage assessment gives a simple, consistent and rational damage indicator for structures.

Fozeya Omar Alkanai - One of the best experts on this subject based on the ideXlab platform.

  • upgrading the seismic capacity of existing rc buildings using buckling restrained braces
    alexandria engineering journal, 2017
    Co-Authors: Hamdy Abouelfath, Mostafa Ramadan, Fozeya Omar Alkanai
    Abstract:

    Abstract Many existing RC buildings do not meet the lateral strength requirements of current seismic codes and are vulnerable to significant damage or collapse in the event of future earthquakes. In the past few decades, buckling-restrained braces have become increasingly popular as a lateral force resisting system because of their capability of improving the strength, the stiffness and the energy absorbing capacity of structures. This study evaluates the seismic upgrading of a 6-story RC-building using single diagonal buckling restrained braces. Seismic evaluation in this study has been carried out by Static Pushover Analysis and time history earthquake Analysis. Ten ground motions with different PGA levels are used in the Analysis. The mean plus one standard deviation values of the roof-drift ratio, the maximum story drift ratio, the brace ductility factors and the member strain responses are used as the basis for the seismic performance evaluations. The results obtained in this study indicate that strengthening of RC buildings with buckling restrained braces is an efficient technique as it significantly increases the PGA capacity of the RC buildings. The results also indicate the increase in the PGA capacity of the RC building with the increase in the amount of the braces.

Ahmed Abed - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of the seismic behavior factor of reinforced concrete frame structures based on comparative Analysis between non linear Static Pushover and incremental dynamic analyses
    Bulletin of Earthquake Engineering, 2015
    Co-Authors: Amar Louzai, Ahmed Abed
    Abstract:

    The seismic behavior factor R (noted q in the european seismic design code, the Eurocode 8) of reinforced concrete frame structures is evaluated based on comparative Analysis between non-linear Static Pushover and non-linear incremental dynamic analyses. For this purpose, three-, six-, and nine-storey reinforced concrete frame structures, considered as low-, medium-, and high-rise frame, respectively, were designed according to reinforced concrete code BAEL 91 and Algerian seismic code RPA 99/Version 2003. Non-linear Static Pushover Analysis using inverted triangular loading pattern and incremental dynamic Analysis using a set of seven time-history earthquake records were carried out to compute the R factor components, such as ductility and overstrength factors, with the consideration of failure criteria at both member and structural levels. The results obtained by non-linear Static Pushover and incremental dynamic analyses are compared. According to the Analysis results, it is observed that in the case of non-linear Static Pushover Analysis, the value of the seismic behavior factor decreases as the number of stories increases, whereas in the case of non-linear incremental dynamic Analysis, the trend observed is not the same: the value of the seismic behavior factor increases as the number of stories increases. This result shows that the value of the seismic behavior factor depends, among others parameters, on the height of a structure, which parameter is not taken into account by the seismic design codes. In the light of the information obtained from incremental dynamic analyses, it is observed that the value of the seismic behavior factor adopted by the seismic design code RPA 99/Version 2003 is overestimated, especially for low-rise frame structure. This paper also provides conclusions and the limitations of this study.

Allin C Cornell - One of the best experts on this subject based on the ideXlab platform.

  • an empirical ground motion attenuation relation for inelastic spectral displacement
    Bulletin of the Seismological Society of America, 2006
    Co-Authors: Polsak Tothong, Allin C Cornell
    Abstract:

    This article presents an empirical ground-motion prediction model (attenuation relation) for inelastic (as opposed to elastic) spectral displacement ( Sdi ) for ground motions without forward directivity effects. It is a function of two earthquake parameters, moment magnitude ( M w) and the closest distance to rupture ( R rup), and two bilinear oscillator parameters, an undamped elastic period ( T ) and a yield displacement ( dy ). The dy is introduced via the predicted median strength-reduction factor (![Graphic][1] ), a proxy for the ratio of elastic spectral displacement ( Sde ) to dy , which is identical with the familiar strength-reduction factor ( R ). The proxy ![Graphic][2] recognizes that R can only be estimated indirectly because it implicitly contains the random variable, Sde , which cannot be known a priori ; therefore, the median estimate or predicted median ( Ŝde ) from a conventional (elastic) ground-motion prediction model is used instead to calculate ![Graphic][3] = Ŝde / dy . For enhanced generality, the inelastic spectral displacement prediction model here is based on a ratio concept, that is, the total model is a (any) conventional elastic prediction model coupled with a new inelastic displacement ratio prediction model, with proper statistical correlation between the two. We empirically consider the dependence of this ratio on source and path effects (i.e., M w and R rup), and find that M w is significant, but R rup is not. The resulting prediction model can easily be added to existing probabilistic seismic-hazard Analysis (psha) software packages with only one extra structure-specific parameter, dy of the oscillator. In practical engineering applications, this will likely have been estimated from the conventional Static Pushover Analysis of the multi-degree-of-freedom (mdof) structure under consideration. The resulting psha product is a hazard curve for Sdi , the inelastic spectral displacement of a nonlinear oscillator. Such a curve can provide a more direct hazard- based target displacement for nonlinear Static procedures (Federal Emergency Management Agency [fema] 356, 2000) and/or a basic input function for new probabilistic seismic-demand analyses that is based on Sdi (as opposed to Sde ) as an efficient and sufficient intensity measure. This new attenuation relationship will be particularly useful in evaluating the performance of existing structures and specified designs with known lateral strength. In particular, unlike most past studies, it does not pre-fix the ductility level. [1]: /embed/inline-graphic-1.gif [2]: /embed/inline-graphic-2.gif [3]: /embed/inline-graphic-3.gif

  • incremental dynamic Analysis
    Earthquake Engineering & Structural Dynamics, 2002
    Co-Authors: Dimitrios Vamvatsikos, Allin C Cornell
    Abstract:

    Incremental dynamic Analysis (IDA) is a parametric Analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. It involves subjecting a structural model to one (or more) ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level. To establish a common frame of reference, the fundamental concepts are analysed, a unified terminology is proposed, suitable algorithms are presented, and properties of the IDA curve are looked into for both single-degree-of-freedom and multi-degree-of-freedom structures. In addition, summarization techniques for multi-record IDA studies and the association of the IDA study with the conventional Static Pushover Analysis and the yield reduction R-factor are discussed. Finally, in the framework of performance-based earthquake engineering, the assessment of demand and capacity is viewed through the lens of an IDA study. Copyright © 2001 John Wiley & Sons, Ltd.

Amjad J Aref - One of the best experts on this subject based on the ideXlab platform.

  • seismic collapse capacity based evaluation and design of frame buildings with viscous dampers using Pushover Analysis
    Journal of Structural Engineering-asce, 2015
    Co-Authors: Mohammadjavad Hamidia, Andre Filiatrault, Amjad J Aref
    Abstract:

    AbstractA simplified procedure is developed for estimating the seismic sidesway collapse capacity of frame building structures incorporating linear and nonlinear viscous dampers. The proposed procedure is based on a robust database of seismic peak displacement responses of viscously damped nonlinear single-degree-of-freedom systems for various seismic intensities and uses nonlinear Static (Pushover) Analysis without the need for nonlinear time history dynamic Analysis. The proposed procedure is assessed by comparing its collapse capacity predictions on 1,190 different building models with those obtained from incremental nonlinear dynamic analyses. A straightforward collapse capacity-based design procedure aimed at achieving a predetermined probability of collapse under maximum considered earthquake event is also introduced for viscously damped structures without extreme soft story irregularities.

  • simplified seismic sidesway collapse capacity based evaluation and design of frame buildings with linear viscous dampers
    Journal of Earthquake Engineering, 2014
    Co-Authors: Mohammadjavad Hamidia, Andre Filiatrault, Amjad J Aref
    Abstract:

    This article describes a simplified procedure for estimating the seismic sidesway collapse capacity of frame building structures incorporating linear viscous dampers. The proposed procedure is based on a robust database of seismic peak displacement responses of viscously damped nonlinear single-degree-of-freedom systems for various seismic intensities and uses nonlinear Static (Pushover) Analysis without the need for nonlinear time history dynamic Analysis. The proposed procedure is assessed by comparing its collapse capacity predictions on 272 different building models with those obtained from incremental dynamic analyses. A straightforward collapse capacity-based design procedure is also introduced for structures without extreme soft story irregularities.