scholarly journals Structural Damping Effects on Dynamic Instability of Subtangentially Loaded and Shear Deformable Beck’s Columns

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Dong-Ju Min ◽  
Jaegyun Park ◽  
Sang-Ho Yeon ◽  
Moon-Young Kim
Keyword(s):  
Dynamic Instability ◽  
Time History ◽  
Linear Instability ◽  
Frequency Equation ◽  
Structural Damping ◽  
Damping Coefficients ◽  
Instability Theory ◽  
History Analysis ◽  
Stability Maps ◽  
Parametric Studies

A frequency equation of externally and internally damped and shear-flexible cantilever columns subjected to a subtangentially follower force is analytically derived in a dimensionless form with relation to the linear instability theory of Beck’s columns. Some parametric studies are then performed with variation of two damping coefficients under the assumption of Rayleigh damping. Based on the analysis results, it is demonstrated that three damping cases in association with flutter loads of Beck’s columns can be selected including one case representative of structural damping. Finally, stability maps of shear-flexible and damped Beck’s columns are constructed for the three damping cases and discussed in the practical range of damping coefficients and shear parameters. In addition, flutter loads and time history analysis results are presented using dimensionless FE analysis and compared with exact solutions.

A Quasi-Vehicle/Bridge Interaction Model for High Speed Railways

2015 ◽  
Vol 31 (2) ◽  
pp. 217-225 ◽  
Author(s):  
J.-D. Yau ◽  
L. Frýba
Keyword(s):  
High Speed ◽  
Equations Of Motion ◽  
Interaction Model ◽  
Time History ◽  
Time Step ◽  
Moving Vehicle ◽  
Coupled Equations ◽  
History Analysis ◽  
High Speed Trains ◽  
Parametric Studies

ABSTRACTVehicle response is served as a reference to evaluate riding comfort of passengers and running safety of moving carriages for high speed trains. In analyzing the vehicle-bridge interaction (VBI) problems, two sets of coupled equations of motion for running vehicles and bridge need to be solved and the VBI system matrices must be updated and factorized at each time step in a time-history analysis. This paper proposed a quasi-VBI model to abridge the complicated computational process, in which the bridge is subjected to only moving static forces of the train loadings, and the moving vehicle over it is excited by the corresponding feedback bridge response. To examine the interacting degree of the vehicle with the bridge, a coupling evaluation index (CEI) is defined as a quantitative assessment of the VBI system. The numerical parametric studies reveal that (1) the mass ratio of vehicle to bridge is the most sensitive parameter affecting the bridge response; (2) increasing bridge damping can reduce the coupling degree of the VBI system at high speeds; (3) the present quasi-VBI model is an efficient and simple tool to predict the vehicle's response with enough accuracy based on engineering approximation.

scholarly journals Parametric Study of P-Delta Effect on Irregular RC Structure with Structural Systems Having Different Density of Shear Walls

2021 ◽  
pp. 492-503
Author(s):  
Yash Patel ◽  
Mr Jigar Zala ◽  
Prof. Deepak R. Tarachandani
Keyword(s):  
Parametric Study ◽  
Dynamic Instability ◽  
Response Spectrum ◽  
Drift Time ◽  
Time History ◽  
Bending Moment ◽  
Shear Walls ◽  
Structural Systems ◽  
Base Shear ◽  
History Analysis

P-Delta analysis affect the seismic responses of structures. When the structure responds elastically, its importance can be insignificant, but it is relevant when the structure responds to an inelastic set. The P-∆ effect normally raises the structural displacement response. Dynamic instability can also occur when the system is exposed to extreme earthquake motions. Plan irregularities can lead to substantial eccentricity between the centre of mass and the centre of rigidity in the RC framed structure, which can lead to a negative lateral and torsional response. Irregular structures require more careful structural evaluation to reach a suitable behaviour during an earthquake. In this research, a parametric study will be conducted on G+29 RC framed buildings having plan irregularity with consideration of the P-delta effect. Time history analysis, response spectrum analysis and static co-efficient method will be conducted to evaluate results of different structural systems and study the parameters like Displacement, Storey drift, Time period, Axial force, Base Shear, Bending Moment, etc with the help of structural analysis software ETABs.

scholarly journals Taking into Account Material Damping in Seismic Analysis of Structures

2020 ◽  
Vol 14 (1) ◽  
pp. 55-59
Author(s):  
Maria S. Barabash ◽  
Bogdan Y. Pysarevskyi ◽  
Yaroslav Bashynskyi
Keyword(s):  
Seismic Analysis ◽  
Time History ◽  
Physical And Mechanical Properties ◽  
Time History Analysis ◽  
Material Damping ◽  
Damping Coefficients ◽  
Modal Damping ◽  
History Analysis ◽  
Earthquake Load ◽  
Displacement Speed

The purpose of this paper is to justify that it is necessary to take into account physical and mechanical properties of soil and different materials of erected structures for damping vibrations in dynamic loads, and to suggest tools for modelling the damping effect (natural or engineering induced) between foundation and soil. A technique is suggested for modelling the behavior of structure in time history analysis taking into account material damping. When solving this problem, the following results were obtained: the physical meaning of material damping was described; Rayleigh damping coefficients were computed through modal damping coefficients. Numerical analysis was carried out for the structure together with soil in earthquake load. Time history analysis was carried out for the problem. Peak values of displacement, speed and acceleration at the roof levels were compared. Analysis results were compared (with and without taking into account material damping). Significant influence of damping on the stress-strain state of the structure has been confirmed.

Numerical Analysis of Seismic Responses of a Concrete Culvert

2014 ◽  
Vol 501-504 ◽  
pp. 1542-1546
Author(s):  
Li Qiang Niu ◽  
De Pi Luo
Keyword(s):  
Seismic Wave ◽  
Time History ◽  
Seismic Loads ◽  
Ground Acceleration ◽  
Differential Model ◽  
Propagation Angle ◽  
History Analysis ◽  
Wide Range ◽  
Parametric Studies ◽  
Internal Forces

A two-dimensional finite differential model is established to find the variation of displacements and stresses of culvert components. The time-history analysis is performed and a wide range of parametric studies are carried out to investigate the influences of height of embankment, ground acceleration and the propagation angle of seismic wave on the responses of the junctions between the culvert components under seismic loads. The results show that the horizontal displacements, the peak values of internal forces under seismic loads increase considerably and nonlinearly with the increases of the height of embankment. The peak values of stresses are sensitive to minor variations of acceleration. And the stresses in the culvert structure are reduced, when the propagation angle of seismic wave increases.

scholarly journals Dynamic Stability of Euler Beams under Axial Unsteady Wind Force

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
You-Qin Huang ◽  
Han-Wen Lu ◽  
Ji-Yang Fu ◽  
Ai-Rong Liu ◽  
Ming Gu
Keyword(s):  
Dynamic Stability ◽  
Dynamic Instability ◽  
Time History ◽  
Wind Load ◽  
Frequency Equation ◽  
Unstable State ◽  
Wind Force ◽  
Eigenvalue Method ◽  
Load Component ◽  
Instability Regions

Dynamic instability of beams in complex structures caused by unsteady wind load has occurred more frequently. However, studies on the parametric resonance of beams are generally limited to harmonic loads, while arbitrary dynamic load is rarely involved. The critical frequency equation for simply supported Euler beams with uniform section under arbitrary axial dynamic forces is firstly derived in this paper based on the Mathieu-Hill equation. Dynamic instability regions with high precision are then calculated by a presented eigenvalue method. Further, the dynamically unstable state of beams under the wind force with any mean or fluctuating component is determined by load normalization, and the wind-induced parametric resonant response is computed by the Runge-Kutta approach. Finally, a measured wind load time-history is input into the dynamic system to indicate that the proposed methods are effective. This study presents a new method to determine the wind-induced dynamic stability of Euler beams. The beam would become dynamically unstable provided that the parametric point, denoting the relation between load properties and structural frequency, is located in the instability region, no matter whether the wind load component is large or not.

scholarly journals Material Damping in Dynamic Analysis of Structures (With LIRA-SAPR Program)

2020 ◽  
Vol 16 (1) ◽  
pp. 63-70
Author(s):  
Mariia Barabash ◽  
Bogdan Pisarevskyi ◽  
Yaroslav Bashynskyi
Keyword(s):  
Numerical Analysis ◽  
Time History ◽  
Time History Analysis ◽  
Viscous Damping ◽  
Material Damping ◽  
Seismic Safety ◽  
Damping Coefficients ◽  
Damping Effect ◽  
Rayleigh Damping ◽  
History Analysis

AbstractThe purpose of this paper is to justify that it is necessary to take account of physical and mechanical properties of soil and different materials of erected structure for damping vibrations in dynamic loads; to suggest tools for modelling the damping effect (natural or engineering induced) between foundation and soil. Certain technique is suggested for modelling behaviour of structure in time history analysis with account of material damping. In the software, the damping effect is modelled in two variants: Rayleigh damping (for structure) and finite element of viscous damping. When solving this problem, the following results were obtained: physical meaning of material damping is described; Rayleigh damping coefficients were computed through modal damping coefficients. Numerical analysis is carried out for the structure together with soil in earthquake load using developed FE of viscous damping. Time history analysis was carried out for the problem. Peak values of displacement, speed and acceleration at the floor levels were compared. Analysis results are compared (with and without account of material damping). Significant influence of damping on the stress-strain state of the structure is confirmed. Scientific novelty of the paper is in the following: the damping effect is proved to happen regardless of the presence of installed structural damping equipment; technique for account of damping with Rayleigh damping coefficients is developed; new damping element is developed – FE of viscous damping (FE 62), its behaviour is described as linear mathematical model. Practical implications of the paper: developed technique and new FE enables the user to carry out numerical analysis properly and work out a set of measures on seismic safety for buildings and structures.

PERILAKU STRUKTUR BAJA TIPE MRF DENGAN BEBAN LATERAL BERDASARKAN SNI 1726-2012 DAN METODE PERFORMANCE BASED PLASTIC DESIGN (PBPD)

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Nidiasari Jati Sunaryati Eem Ikhsan
Keyword(s):  
Pushover Analysis ◽  
Time History ◽  
Time History Analysis ◽  
Plastic Design ◽  
History Analysis ◽  
Non Linear ◽  
Static Pushover Analysis

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 .

Response Law and Influencing Factors of the Soil under Action of Pile Driving Vibration Based on Midas/GTS

2013 ◽  
Vol 353-356 ◽  
pp. 979-983
Author(s):  
Dong Zhang ◽  
Jing Bo Su ◽  
Hui De Zhao ◽  
Hai Yan Wang
Keyword(s):  
Damping Ratio ◽  
Large Diameter ◽  
Time History ◽  
Pile Driving ◽  
Analysis Model ◽  
Vibration Load ◽  
History Analysis ◽  
Study Results ◽  
Propagation Law ◽  
Dynamic Time

Due to the upgrade and reconstruct of a high-piled wharf, the piling construction may cause the damage of the large diameter underground pipe of a power plant nearby. For this problem, a dynamic time-history analysis model was established using MIDAS/GTS program. Based on the analysis of the pile driving vibration and its propagation law, some parameters, such as the modulus of the soil, the Poissons ratio of soil, the action time of vibration load and the damping ratio of the soil that may have an effect on the response law of the soil, were studied. The study results not only serve as an important inference to the construction of this case, but also accumulate experience and data for other similar engineering practices.

scholarly journals Record-to-record variability and code-compatible seismic safety-checking with limited number of records

2021 ◽  
Author(s):  
Fatemeh Jalayer ◽  
Hossein Ebrahimian ◽  
Andrea Miano
Keyword(s):  
Seismic Hazard ◽  
Linear Time ◽  
Time History ◽  
Time History Analysis ◽  
Seismic Safety ◽  
Hazard Curve ◽  
History Analysis ◽  
Non Linear ◽  
Seismic Hazard Curve ◽  
Cloud Analysis

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.

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