scholarly journals Non-Linear Analysis of Asymmetric Structures

Author(s):  
Rahul Patil Patlolla

Abstract: The study of multi-story building behaviour always depends on strength, durability, stiffness and adequacy of the regular configuration of the structures. Understanding the seismic behaviour of asymmetric structures is a challenging task, considering the aspect of irregularity (either in the plan or elevation) is generally known as asymmetric. Various researchers had studied the behaviour of this asymmetrical building by taking into considerations of different approaches such as plan configuration, vertical irregularity, mass and stiffness, in different methods of analysis. The irregular structures are less prone to the seismic forces, hence there is a need to study and specify some improvements in codal provisions for this type of asymmetrical structures. In the present study, we have considered a plan irregular structure (which replicates the Microsoft building at Hyderabad). The overall structural behaviour of asymmetrical building is investigated under different earthquake cases, such as with El-Centro, Loma and Uttarkashi database. Analysis of structure (using software program E-TABS V-17) for various earthquake intensities and checking for multiple criteria at every level for essential practice. The non-linear methods Time History analysis is carried over to find the structural behaviour. Keywords: multi-story building, plan irregularity, Time history analysis

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Nidiasari Jati Sunaryati Eem Ikhsan

Struktur rangka baja pemikul momen merupakan jenis struktur baja tahan gempa yang populer digunakan. Daktilitas struktur yang tinggi merupakan salah satu keunggulan struktur ini, sehingga mampu menahan deformasi inelastik yang besar. Dalam desain, penggunaan metode desain elastis berupa evaluasi non-linear static (Pushover analysis) maupun evaluasi non-linear analisis (Time History Analysis) masih digunakan sebagai dasar perencanaan meskipun perilaku struktur sebenarnya saat kondisi inelastik tidak dapat digambarkan dengan baik. Metode Performance-Based Plastic Design (PBPD) berkembang untuk melihat perilaku struktur sebenarnya dengan cara menetapkan terlebih dahulu simpangan dan mekanisme leleh struktur sehingga gaya geser dasar yang digunakan adalah sama dengan usaha yang dibutuhkan untuk mendorong struktur hingga tercapai simpangan yang telah direncanakan. Studi dilakukan terhadap struktur baja 5 lantai yang diberi beban gempa berdasarkan SNI 1726, 2012 dan berdasarkan metode PBPD. Hasil analisa menunjukkan bahwa struktur yang diberi gaya gempa berdasarkan metode PBPD mencapai simpangan maksimum sesuai simpangan rencana dan kinerja struktur yang dihasilkan lebih baik .


Author(s):  
Fatemeh Jalayer ◽  
Hossein Ebrahimian ◽  
Andrea Miano

AbstractThe Italian code requires spectrum compatibility with mean spectrum for a suite of accelerograms selected for time-history analysis. Although these requirements define minimum acceptability criteria, it is likely that code-based non-linear dynamic analysis is going to be done based on limited number of records. Performance-based safety-checking provides formal basis for addressing the record-to-record variability and the epistemic uncertainties due to limited number of records and in the estimation of the seismic hazard curve. “Cloud Analysis” is a non-linear time-history analysis procedure that employs the structural response to un-scaled ground motion records and can be directly implemented in performance-based safety-checking. This paper interprets the code-based provisions in a performance-based key and applies further restrictions to spectrum-compatible record selection aiming to implement Cloud Analysis. It is shown that, by multiplying a closed-form coefficient, code-based safety ratio could be transformed into simplified performance-based safety ratio. It is shown that, as a proof of concept, if the partial safety factors in the code are set to unity, this coefficient is going to be on average slightly larger than unity. The paper provides the basis for propagating the epistemic uncertainties due to limited sample size and in the seismic hazard curve to the performance-based safety ratio both in a rigorous and simplified manner. If epistemic uncertainties are considered, the average code-based safety checking could end up being unconservative with respect to performance-based procedures when the number of records is small. However, it is shown that performance-based safety checking is possible with no extra structural analyses.


2021 ◽  
Vol 879 ◽  
pp. 232-242
Author(s):  
A.N. Refani ◽  
Yuyun Tajunnisa ◽  
K. Yudoprasetyo ◽  
F. Ghifari ◽  
D.I. Wahyudi

Indonesia is a country located in the convergence of small plates and large plates. Furthermore, this causes Indonesia to be high potentially to earthquake hazards. The newest geological research published by Geophysical Research Letter (2016) shows the existence of Fault Kendeng, a fault stretches along 300 km from South Semarang, Central Java, to East Java with a movement of 0,05 millimeter per year [1]. As a result of its research, an evaluation using a non-linear time history analysis for structural buildings is necessary. The objective of this study is to evaluate structural buildings using a non-linear time history analysis. This study applies DSHA (Deterministic Seismic Hazard Analysis) method to obtain acceleration time history on bedrocks. Since the record of ground movement in Indonesia is limited, the attenuation function equation used to scale and match other country’s time acceleration history data. SSA (Site-Specific Analysis) is used to propagate earthquake acceleration from bedrocks to the surface. The earthquake acceleration on the surface generates as the earthquake load on the buildings. The results of Kendeng fault earthquake simulation using non-linear time history analysis shows that column members capacity is more robust than beam members capacity which the beam collapse mechanism occurs initially. From the maximum total drift ratio result, when the Kendeng fault earthquake occurs, the building structure performance level is at collapse prevention level Based on ATC-40 [2]. This research result shows that 96,7% of plastic hinge has not yielded. However, some elements are already damaged. Since most damage members are column, then it may require column strengthening to enhance maximum performance level at life safety condition category.


2018 ◽  
Vol 7 (2.29) ◽  
pp. 955
Author(s):  
Mohammed Ziauddin Patowary ◽  
Abdul Kadir Marsono

Due to the urbanization multi-story building with underground story for parking space and storage are very common in practice. Now a day, seismic energy dissipating devices are being used for various types of structures and located in basements which are difficult to maintain.  The main objective is to evaluate the effectiveness of horizontal dampers in the ground floor level of the multi-story building above basement. Among different types of dampers, visco-elastic [VE] dampers are used for this numerical study. Comparing with other types of passive energy dissipating devices, visco-elastic [VE] dampers are considered most suitable. For the better understanding of the effectiveness of horizontal dampers, stiff foundation system is considered thus soil-structure interaction is omitted. In this numerical study, seismic response of different hypothetical structures analyzed having different underground stories and horizontal dampers only in the ground level. Modeling and analysis of the structures and installation of the dampers are done by using finite element modeling software [ETABS]. Time history analysis was used to simulate the response of the structures. Sabah earthquake [05/June/2015] with the PGA of 0.126g was used for the time history analysis. Different dynamics parameters such as natural time period, displacement, base shear and inter-story drift were evaluated. Changes in the results among the structures demonstrated the efficiency of horizontal dampers. Optimum locations of the horizontal dampers were also revealed in this study in the basis of the analysis results.  


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