scholarly journals Local, Story, and Global Ductility Evaluation for Complex 2D Steel Buildings: Pushover and Dynamic Analysis

2019 ◽  
Vol 9 (1) ◽  
pp. 200 ◽  
Author(s):  
Mario D. Llanes-Tizoc ◽  
Alfredo Reyes-Salazar ◽  
Eden Bojorquez ◽  
Juan Bojorquez ◽  
Arturo Lopez-Barraza ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Pushover Analysis ◽  
Strong Motion ◽  
Steel Buildings ◽  
Structural Element ◽  
Mean Values ◽  
Weak Beam ◽  
A Value ◽  
Moment Resisting ◽  
Ductility Capacity

A numerical investigation regarding ductility evaluation of steel buildings with moment resisting steel frames is conducted. Bending (µLϕ) and tension (µLδ) local ductilities as well as story (µS) and global ductilities are studied. Global ductility is calculated as the mean values of story ductilities (µGS) and as the ratio of the maximum inelastic to yielding top displacements (µGt). The ductility capacity is associated to drifts of about 5%. Ductility values significantly may vary with the strong motion, ductility definition, structural element, story number, type of analysis, and model. µLϕ is much larger for beams than for columns. Even though the demands of µLδ are considered an important issue they are less relevant than µLϕ. µS is much smaller than µLϕ for beams. µGS for dynamic analysis give reasonable values, but µGt does not. µLϕ, µS and µGS obtained from pushover are larger than those obtained from dynamic analysis and unlike the case of dynamic analysis, µLϕ tend to increase with the story number showing an opposite trend. Considering that: µGt for dynamic analysis results in unreasonable values, pushover analysis does not consider energy dissipation, the strong column–weak beam (SCWB) concept was followed in the model designs, and µLδ is not relevant in framed steel buildings, the ratio (RLG) of global to local ductility capacity is calculated as the ratio of µGS to µLϕ of beams, for dynamic analysis. A value of 1/3 is proposed. Thus, if bending local ductility capacity is stated as the basis for the design, the global ductility capacity can be easily estimated.

Ductility Reduction Factors for Steel Buildings Modeled as 2D and 3D Structures

2014 ◽  
Vol 595 ◽  
pp. 166-172
Author(s):  
Alfredo Reyes-Salazar ◽  
Eden Bojorquez ◽  
Achintya Haldar ◽  
Arturo Lopez-Barraza ◽  
J. Luz Rivera-Salas
Keyword(s):  
Lateral Force ◽  
Reduction Factor ◽  
Steel Buildings ◽  
Structural Representation ◽  
Global Response ◽  
A Value ◽  
Mdof Systems ◽  
Moment Resisting ◽  
2D And 3D ◽  
Reduction Factors

The global ductility parameter (μG), commonly used to represent the capacity of a structure to dissipate energy, and the associated ductility reduction factor (Rμ), are estimated for steel buildings with perimeter moment resisting frames (PMRF), which are modeled as 2D and 3D complex MDOF systems. Results indicate that the μG value of 4, commonly assumed for moment resisting steel frames, cannot be justified. A value of 3 is more reasonable. The values of μG and Rμ may be quite different for 2D and 3D structural representations or for local and global response parameters, showing the limitation of the commonly used Equivalent Lateral Force Procedure (ELFP). Thus, the ductility and ductility reduction factors obtained from simplified structural representation must be taken with caution.

scholarly journals Seismic Performance Evaluation of Existing RC Buildings Without Seismic Details. Comparison of Nonlinear Static Methods and IDA

2016 ◽  
Vol 10 (1) ◽  
pp. 158-179 ◽  
Author(s):  
Constantinos C. Repapis
Keyword(s):  
Seismic Performance ◽  
Nonlinear Dynamic ◽  
Pushover Analysis ◽  
Strong Motion ◽  
Rc Buildings ◽  
Mean Values ◽  
Behaviour Factor ◽  
Seismic Performance Evaluation ◽  
N2 Method ◽  
Dynamic Analyses

The inelastic response of existing reinforced concrete (RC) buildings without seismic details is investigated, presenting the results from more than 1000 nonlinear analyses. The seismic performance is investigated for two buildings, a typical building form of the 60s and a typical form of the 80s. Both structures are designed according to the old Greek codes. These building forms are typical for that period for many Southern European countries. Buildings of the 60s do not have seismic details, while buildings of the 80s have elementary seismic details. The influence of masonry infill walls is also investigated for the building of the 60s. Static pushover and incremental dynamic analyses (IDA) for a set of 15 strong motion records are carried out for the three buildings, two bare and one infilled. The IDA predictions are compared with the results of pushover analysis and the seismic demand according to Capacity Spectrum Method (CSM) and N2 Method. The results from IDA show large dispersion on the response, available ductility capacity, behaviour factor and failure displacement, depending on the strong motion record. CSM and N2 predictions are enveloped by the nonlinear dynamic predictions, but have significant differences from the mean values. The better behaviour of the building of the 80s compared to buildings of the 60s is validated with both pushover and nonlinear dynamic analyses. Finally, both types of analysis show that fully infilled frames exhibit an improved behaviour compared to bare frames.

scholarly journals Special Moment Resistant Steel Buildings

2021 ◽  
pp. 444-448
Author(s):  
Deepan Dev B ◽  
Dr V Selvan
Keyword(s):  
Pushover Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Building Structures ◽  
Braced Frames ◽  
Steel Buildings ◽  
Braced Frame ◽  
Moment Resisting ◽  
Frame Systems ◽  
Nonlinear Time History

The seismic response of special moment-resisting frames (SMRF), buckling restrained braced (BRB) frames and self-centering energy dissipating (SCED) braced frames is compared when used in building structures many stories in height. The study involves pushover analysis as well as 2D and 3D nonlinear time history analysis for two ground motion hazard levels. The SCED and BRB braced frames generally experienced similar peak interstory drifts. The SMRF system had larger interstory drifts than both braced frames, especially for the shortest structures. The SCED system exhibited a more uniform distribution of the drift demand along the building height and was less prone to the biasing of the response in one direction due to P-Delta effects. The SCED frames also had significantly smaller residual lateral deformations. The two braced frame systems experienced similar interstory drift demand when used in torsional irregular structures.

Applying Adaptive Pushover Analysis to Estimate Incremental Dynamic Analysis Curve

2020 ◽  
Vol 14 (04) ◽  
pp. 2050016
Author(s):  
Hamid Reza Ahmadi ◽  
Navideh Mahdavi ◽  
Mahmoud Bayat
Keyword(s):  
Dynamic Analysis ◽  
Limit State ◽  
Pushover Analysis ◽  
Computational Cost ◽  
Time History ◽  
Incremental Dynamic Analysis ◽  
History Analysis ◽  
Moment Resisting ◽  
Displacement Based ◽  
Adaptive Pushover

To estimate seismic demand and capacity of structures, it has been suggested by researchers that Incremental Dynamic Analysis (IDA) is one of the most accurate methods. Although this method shows the most accurate response of the structure, some problems, such as difficulty in modeling, time-consuming analysis and selection of the earthquake records, encourage researchers to find some ways to estimate the dynamic response of structures by using static nonlinear analysis. The simplicity of pushover analysis in evaluating structural nonlinear response serves well as an alternative to the time-history analysis method. In this paper, based on the concepts of the displacement-based adaptive pushover (DAP), a new approach is proposed to estimate the IDA curves. The performance of the proposed method has been investigated using 3- and 9-story moment-resisting frames. In addition, the results were compared with exact IDA curves and IDA curves developed by the modal pushover analysis (MPA) based method. For evaluation, IDA curves with 16%, 50% and 84% fractile were estimated. Using the results, [Formula: see text] capacities corresponding to Collapse Prevention (CP) limit state were calculated and assessed. Finite element modeling of the structures has been carried out by using ZEUS-NL software. Based on the achieved results, the proposed approach can estimate the capacity of the structure accurately. The significant advantage of the applied approach is the low computational cost and desirable accuracy. The proposed approach can be used to develop the approximate IDA curves.

scholarly journals Energy Dissipation and Local, Story, and Global Ductility Reduction Factors in Steel Frames under Vibrations Produced by Earthquakes

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Alfredo Reyes-Salazar ◽  
Edén Bojórquez ◽  
Juan Bojorquez ◽  
Federico Valenzuela-Beltran ◽  
Mario D. Llanes-Tizoc
Keyword(s):  
Energy Dissipation ◽  
Reduction Factor ◽  
Point Of View ◽  
Dissipated Energy ◽  
Steel Buildings ◽  
A Value ◽  
Local Point ◽  
Ductility Reduction Factor ◽  
Ductility Capacity ◽  
Reduction Factors

Ductility plays a central role in seismic analysis and design of steel buildings. A numerical investigation regarding the evaluation of energy dissipation, ductility, and ductility reduction factors for local, story, and global structural levels is conducted. Some steel buildings and strong motions, which were part of the SAC Steel Project, are used. Bending local ductility capacity (µLϕ) of beams can reach values of up to 20, as shown in experimental investigations. The values are larger for medium than for low-rise buildings, reflecting the effect of the structural complexity on µLϕ. Most of the dissipated energy occurs on beams; however, resultant stresses at columns are also significantly reduced by beam yielding. A value of 1/3 is proposed for the ratio of global to local ductility; thus, if local ductility capacity is stated as the basis for the design, global ductility capacity can be calculated by using this ratio. It is implicitly assumed in seismic codes that the magnitude of the global ductility reduction factor is about 4; according to the results found in this paper, it is not justified; a value of 3 is observed to be more reasonable. According to the well-known ratio of the ductility reduction factor to ductility, this ratio should be unity for the models under consideration; the results of this study indicate that, for global response parameters, a value of 3/4 is more appropriate and that, for local response parameters, values larger than 2 can be reached; the implication of this is that using simplified methods like the static equivalent lateral force may result in nonconservative designs from a global structural point of view, but in conservative designs from a local point of view. A value of 8 is proposed for the ratio of the global ductility reduction factor to the global normalized energy.

Normal levels of vitamin A in tissues of the Syrian hamster (Mesocricetus auratus) determined colorimetrically

1988 ◽  
Vol 22 (2) ◽  
pp. 117-121 ◽  
Author(s):  
M. E. Robinson ◽  
A. M. Verrinder Gibbins ◽  
M. H. Hardy
Keyword(s):  
Vitamin A ◽  
Syrian Hamster ◽  
Cheek Pouch ◽  
Standard Diet ◽  
Male And Female ◽  
Mean Values ◽  
A Value ◽  
Significant Difference ◽  
Wet Weight ◽  
The Mean

Vitamin A levels in tissues of 20 normal adult hamsters on a standard diet were measured colorimetrically. No significant difference between male and female animals was found for any of the tissues sampled. The mean vitamin A value for blood plasma in 20 animals was 53·4 μg/dl. Mean values for liver, kidneys, flank skin and cheek pouch were 813, 1·29, 1·84 and 1·31 mg/g wet weight, respectively. The vitamin assay was less suitable for small organs such as trachea.

Seismic capacity estimation of a reinforced concrete containment building considering bidirectional cyclic effect

2018 ◽  
Vol 22 (5) ◽  
pp. 1106-1120
Author(s):  
Zhi Zheng ◽  
Changhai Zhai ◽  
Xu Bao ◽  
Xiaolan Pan
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Geometric Mean ◽  
Pushover Analysis ◽  
Incremental Dynamic Analysis ◽  
Dissipated Energy ◽  
Seismic Capacity ◽  
Capacity Estimation ◽  
Earthquake Intensity ◽  
Static Pushover Analysis

This study serves to estimate the seismic capacity of the reinforced concrete containment building considering its bidirectional cyclic effect and variations of energy. The implementation of the capacity estimation has been performed by extending two well-known methods: nonlinear static pushover and incremental dynamic analysis. The displacement and dissipated energy demands are obtained from the static pushover analysis considering bidirectional cyclic effect. In total, 18 bidirectional earthquake intensity parameters are developed to perform the incremental dynamic analysis for the reinforced concrete containment building. Results show that the bidirectional static pushover analysis tends to decrease the capacity of the reinforced concrete containment building in comparison with unidirectional static pushover analysis. The 5% damped first-mode geometric mean spectral acceleration strongly correlates with the maximum top displacement of the containment building. The comparison of the incremental dynamic analysis and static pushover curves is employed to determine the seismic capacity of the reinforced concrete containment building. It is concluded that bidirectional static pushover and incremental dynamic analysis studies can be used in performance evaluation and capacity estimation of reinforced concrete containment buildings under bidirectional earthquake excitations.

scholarly journals Reinforced concrete bridge pier ductility analysis for different levels of detailing

2017 ◽  
Vol 10 (5) ◽  
pp. 1042-1050
Author(s):  
R. W. SOARES ◽  
S. S. LIMA ◽  
S. H. C. SANTOS
Keyword(s):  
Reinforced Concrete ◽  
Axial Loading ◽  
Structural Element ◽  
Reinforced Concrete Column ◽  
Elastoplastic Behavior ◽  
Response Modification Factor ◽  
Concrete Confinement ◽  
Plastic Displacement ◽  
Displacement Based ◽  
Ductility Capacity

Abstract The structural design under seismic loading has been for many years based on force methods to consider the effects of energy dissipation and elastoplastic behavior. Currently, displacement-based methods are being developed to take into account elastoplastic behavior. These methods use moment-curvature relationships to determine the ductility capacity of a structural element, which is the deformation capacity of the element before its collapse. The greater the plastic displacement or rotation a structural member can achieve before it collapses, the more energy it is capable of dissipating. This plastic displacement or rotation capacity of a member is known as the member ductility, which for reinforced concrete members is directly related to efficient concrete confinement. This study investigates at which extents transverse reinforcement detailing influences reinforced concrete column ductility. For this, a bridge located in Ecuador is modeled and analyzed, and its ductility evaluated considering several cases of axial loading and concrete confinement levels. After the performed displacement-based analyses, it is verified whether the response modification factor defined by AASHTO is adequate in the analyzed case.

scholarly journals Assessment of seismic responses toward multi-story buildings of steel special moment resisting frame by considering the setback irregularities

2021 ◽  
Vol 331 ◽  
pp. 05007
Author(s):  
Ridho Aidil Fitrah ◽  
Masrilayanti Masrilayanti ◽  
Gita Zakiah Putri ◽  
Zev Al Jauhari
Keyword(s):  
Response Spectrum ◽  
Nonlinear Static Analysis ◽  
Steel Buildings ◽  
Seismic Responses ◽  
Base Shear ◽  
Moment Frame ◽  
Moment Resisting ◽  
Drift Limit ◽  
Special Moment Resisting Frame ◽  
Special Moment Frame

Setback irregularities are considered where discontinuity between adjacent stories is excessive. This irregularity caused the probability of high damage at structures subjected to strong earthquake motion. For this purpose, this study was conducted by modeling the steel special moment frame (SMF) structures using a finite element calculation program with nonlinear static analysis compared to Padang city’s response spectrum. The buildings are also modeled with two types of setbacks: single and multiple setbacks. The results of this paper are discussed including the explanation of many parameters that relate to elastic and inelastic seismic responses of steel special moment frame (SMF). Based on the results, the setback irregularities, both single and multiple setbacks, the inelastic seismic responses are adequately sufficient to SNI 1726 2019 regarding drift limit. The other seismic responses are also discussed in terms of fundamental periods, inter-story drifts, story stiffness, and base shear. Referred to Indonesian Seismic Provision, SNI 1726 2019, it is found that single setback building has more adequate than multiple setbacks in terms of seismic responses. Then, the seismic assessments between these setbacks are explained to address the recommendations about future prevention toward damages and failures in steel buildings.

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