Target acceleration in multimodal pushover method for R/C frames
Author: Ivan Balić , BSc. CE University of Split :Prof. Ante Mihanović, PhD. CE University of Split:Prof. Boris Trogrlić, PhD. CE University of Split | Size: 1.8 MB | Format:PDF | Quality:Unspecified | Year: 2013 | pages: 14
The procedure of searching the target ground acceleration as a measure of the lowest seismic
resistance is presented in the paper. This objective is achieved by the multimodal pushover
analysis based on the envelope principle. The pushover method founded on the linear combination
of modes (L), and on mode combinations as a square root of the sum of the squares (SRSS), is
presented. Examples of 5-storey and 9-storey R/C frames point to a highly significant influence
of higher modes. The failure ground acceleration in multimodal pushover analysis is significantly
lower, and even several times lower, compared to the single mode acceleration.
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Pushover Analysis of 4 Storey’s Reinforced Concrete Building
Author: Kavita Golghate :Vijay Baradiya: Amit Sharma | Size: 99 KB | Format:PDF | Quality:Unspecified | Publisher: International Journal of Latest Trends in Engineering and Technology (IJLTET) | Year: 2013 | pages: 5
The earthquakes in the Indian subcontinent have led to an increase in the seismic zoning factor over many
parts of the country. Also, ductility has become an issue for all building that was designed and detailed using earlier
versions of the codes. Under such circumstances, seismic qualification of building has become extremely important.
The structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis.
Modeling for such analysis requires the determination of the nonlinear properties of each component in the structure,
quantified by strength and deformation capacities, which depend on the modeling assumptions. Pushover analysis is
carried out for either user-defined nonlinear hinge properties or default-hinge properties, available in some
programs based on the FEMA-356 and ATC-40 guidelines. This paper aims to evaluate the zone –IV selected
reinforced concrete building to conduct the non-linear static analysis (Pushover Analysis). The pushover analysis
shows the pushover curves, capacity spectrum, plastic hinges and performance level of the building. The non-linear
static analysis gives better understanding and more accurate seismic performance of buildings of the damage or
failure element.
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The aim of this research is to investigate effect of hysteresis loops in static nonlinear analysis.
One of the inefficiencies of static nonlinear analysis is that nonlinear behavior of structural elements due to
cyclic deformations is approximately considered in the analysis, and only one quarter of a full hysteretic loop
is considered. For investigating the effect of this inefficiency in analysis results, three intermediate concrete
moment frames are selected. These models are selected from regular RC structures. The notified procedures in
FEMA-356 and proposed plastic hinges in this guideline are utilized for performing static nonlinear analysis.
A coefficient for consideration of stiffness degradation and strength deterioration is proposed by FEMA-356 in
nonlinear static analysis. This coefficient for intermediate RC moment frames is equal to unity. For calculation
of this coefficient, in this paper, the nonlinear dynamic analysis is used. Clough and Takeda Hysteretic loops
and a hysteretic loop that considers effects of severe stiffness degradation, strength deterioration and pinching
are assumed in nonlinear dynamic analysis. By comparison of results the value of this coefficient is obtained
25% more than the value proposed by FEMA-356.
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This paper presents a simple method to calculate pushover curves for
asymmetric structure with displacement-dependent passive energy dissipation devices
(DDPEDDs). The method analyzes the deformation of a symmetric structure in
translation and in torsion. These results are then combined in order to calculate the
pushover curve for an asymmetric structure with DDPEDDs. The numerical results
obtained by using the simple analysis method are then compared to the results obtained
from the analysis of the models using the software SAP2000. The results show that the
simple analysis method can be an effective tool for engineering analysis.
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P ERFORMANCE OF PUSHOVER PROCEDURE IN EVALUATING THE SEISMIC ADEQUACY OF REINFORCED CONCRETE FRAMES
Author: A. Shuraim , A. Charif | Size: 245 KB | Format:PDF | Quality:Unspecified | pages: 14
The nonlinear static analytical procedure (Pushover) as introduced by ATC-40 was applied for
the evaluation of existing design of a reinforced concrete frame, in order to examine the
applicability of the pushover for evaluating design of new buildings. Potential structural
deficiencies in the frame were assessed by the code seismic-resistant design and pushover
approaches, for the sake of comparison. In the first approach, the potential deficiencies were
determined by redesigning under one selected seismic combination in order to show which
members would require additional reinforcement. In the second approach, a pushover analysis
was conducted to assess the seismic performance of the frame and detect the locations of the
plastic hinges. The paper shows that vulnerability locations revealed from the two procedures
are significantly different, where the latter procedure tends to overestimate column strength,
consequently, concealing earlier detection of column weaknesses. The paper provides rational
explanations for the apparent discrepancy that can be taken into consideration in order to make
pushover methodology applicable when designing or evaluating existing design of new
buildings.
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A DISPLACEMENT-BASED ADAPTIVE PUSHOVER ALGORITHM FOR ASSESSMENT OF VERTICALLY IRREGULAR FRAMES
Author: RUI PINHO ; STELIOS ANTONIOU | Size: 259 KB | Format:PDF | Quality:Unspecified | Publisher: 4th European Workshop on the Seismic Behaviour of Irregular and Complex Structures Thessaloniki, Greece, 26–27 August 2005 | Year: 2005 | pages: 16
Due to the unvarying nature of the applied displacement loading vector, conventional (nonadaptive) displacement-based pushover analysis can conceal important structural characteristics, such as strength irregularities and soft storeys, should the displacement pattern adopted at the start of the analysis not correspond to the structure’s post-yield failure mechanism. Consequently, when only non-adaptive static nonlinear analysis tools are available, as has been the case throughout the past, force-based pushover does constitute a preferable choice over its displacement-based counterpart. On the other hand, however, if one
is able to apply displacements, rather than forces, in an adaptive fashion, that is, with the
possibility of updating the displacement loading pattern according to the structural properties of the model at each step of the analysis, then a conceptually appealing deformation-based nonlinear static analysis tool would be obtained. The present study focuses therefore on the
verification of the accuracy of such an innovative displacement-based adaptive pushover method (DAP), to estimate the response characteristics of vertically irregular frames subjected
to earthquake excitation.
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A series of pushover analyses on two-dimensional RC frames, part of an office building, are
performed. They constitute a detailed parametric study, varying the number of stories and its height, and also
the bay width. Regarding the stated objective, several commercial packages universally used in the design of
civil engineering structures were used, namely SAP 2000, SeismoStruct and MIDAS. To represent the
influence of the masonry infill panels, the equivalent tie method is used considering several values for the tie
width. The influence of other parameters, on the structural behavior of the RC frame through a pushover
analysis, is also analyzed: the confinement of the structural elements (columns and beams) and the length and
location of the plastic hinges forming near the end of the structural elements. Finally, it is also parameterized
the behavior of the structure when submitted to different load patterns, such as: uniform and modal, as
suggested in the Eurocode8, and triangular. Major conclusions of the study elaborated are presented and
future developments are pointed-out in order to deepen the pushover analysis of two dimensional RC frames.
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Autodesk Inc., a world leader in 3D design software for entertainment, natural resources, manufacturing, engineering, construction, and civil infrastructure, announced the release of Robot Structural Analysis 2015, is a complements building information (BIM) with coordinated digital analysis and design for structural engineers.
Autodesk Robot Structural Analysis Professional software provides structural engineers with advanced structural analysis capabilities for even large and complex structures. Analyze models with powerful finite element auto-meshing, nonlinear algorithms, and a comprehensive library of country-specific design codes.
Autodesk Robot Structural Analysis Professional is faster and more flexible enabling structural analysis to be performed more quickly and easily. The software supports smoother workflow and interoperability with Autodesk Revit Structure software, the Autodesk structural engineering building information modeling (BIM) solution. The software's open API (application programming interface) enables design and analysis capabilities to be extended to other Autodesk software solutions and third party software.
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