Masonry Spires: 3D Models to Understand their Seismic Vulnerability

2019 ◽  
Vol 817 ◽  
pp. 317-324
Author(s):  
Elena Zanazzi ◽  
Eva Coïsson ◽  
Daniele Ferretti ◽  
Alessio Lorenzelli
Keyword(s):  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Linear Time ◽  
Numerical Models ◽  
Nonlinear Dynamic Analysis ◽  
Nonlinear Static Analysis ◽  
Time Step ◽  
Epicentral Area ◽  
Finite Element Software ◽  
Bell Tower

The May 2012 Emilia earthquake has highlighted the important vulnerability of masonry spires at the top of bell towers of churches. Indeed, almost half of those in the epicentral area have shown a typical damage mechanism consisting in the shear sliding and overturning of the top of the spire. Given the recurrence of this phenomenon, the present paper tries to provide a contribution to the comprehension of the seismic behaviour of the spires through the numerical analysis of three case studies. In particular, the work analyses the spires of the churches of San Nicola di Bari in Cortile, near Carpi (MO); Sant'Egidio in Cavezzo (MO), and Sant'Agostino in Sant'Agostino (FE). The numerical models of these masonry structures were made using Abaqus Finite Element software. After the creation of the three-dimensional geometric models, a first nonlinear static analysis of the entire bell tower was performed adopting for masonry the Abaqus “concrete damage plasticity model”. Once the stability of the bell tower was verified for dead loads, the non-linear time-step dynamic analysis was faced. This required the definition of the seismic input at the base of the tower, through the accelerograms recorded by the closest stations. The nonlinear dynamic analysis of the global model of the bell tower provided the floor response spectra at the base and at the top of the spire. Indeed the comparison between spectra at the ground and at the top highlights the filter effect of the stem of the bell tower with a significant increase in accelerations at the top. This effect may explain the widespread damage observed at the top of the spires. Eventually, three different non-invasive intervention techniques were proposed in compliance with the principles of restoration and were modelled to compare their behaviour.

scholarly journals Evaluation of p-delta effect in structural seismic response

2018 ◽  
Vol 162 ◽  
pp. 04019 ◽  
Author(s):  
Sardasht Sardar ◽  
Ako Hama
Keyword(s):  
Seismic Response ◽  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Time History ◽  
Steel Structure ◽  
Nonlinear Static Analysis ◽  
Structural Behavior ◽  
Finite Element Software ◽  
History Analysis ◽  
Nonlinear Static

Numerous recent studies have assessed the effect of P-Delta on the structures. This paper investigates the effect of P-Delta in seismic response of structures with different heights. For indicating the effect of P-Delta, nonlinear static analysis (pushover analysis) and nonlinear dynamic analysis (Time history analysis) were conducted by using finite element software. The results showing that the P-Delta has a significant impact on the structural behavior mainly on the peak amplitude of building when the height of the structures increased. In addition, comparison has been made between concrete and steel structure.

scholarly journals Wavelet-based Decomposition of Ground Acceleration for Efficient Calculation of Seismic Response in Elastoplastic Structures

2020 ◽  
Author(s):  
Reza Kamgar ◽  
Noorollah Majidi ◽  
Ali Heidari
Keyword(s):  
Wavelet Transform ◽  
Dynamic Analysis ◽  
Continuous Wavelet Transform ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Continuous Wavelet ◽  
Frequency Content ◽  
Time Step ◽  
Integration Schemes ◽  
The Waves

The nonlinear dynamic analysis provides a more accurate simulation of the structural behavior against earthquakes. On the other hand, this analysis method is time-consuming since the time-step integration schemes are used to calculate the responses of the structure. Wavelet transform is also considered as one of the strong computing tools in studying the properties of the waves. The continuous wavelet transform is a time-frequency study and examines the frequency content of the waves while, the discrete wavelet transform is used to reduce sampling data and also to eliminate the noise of the waves. In this paper, the discrete and continuous wavelet transforms are used to reduce the wave sampling and therefore to reduce the required time for analysis. In this regard, eight near- and far- field earthquakes are studied. The frequency content of the earthquake is investigated by the Fourier spectrum and the continuous wavelet transform. The results show that the first five frequencies for the main earthquakes are similar to those values of earthquakes obtained by wavelet transform. Besides, it is shown that using wavelet transform for the main and decomposed earthquakes indicates that the duration of strong ground motion and the time of dominant frequency occur approximately in the same domain. Finally, it is concluded that the required calculation time reduces to about 80 % with an error less than 6 % when the main earthquake is decomposed by wavelet transform and the approximation waves are used in the nonlinear dynamic analysis.

Geometric Nonlinear Dynamic Analysis of Tapered Steel Members

2020 ◽  
Author(s):  
Yasir F. Al-Lebban
Keyword(s):  
Dynamic Analysis ◽  
Mass Matrix ◽  
Nonlinear Dynamic Analysis ◽  
Axial Deformation ◽  
Step Size ◽  
Time Step ◽  
Time Step Size ◽  
Geometric Nonlinear ◽  
Steel Members ◽  
Mass Matrices

In this study, a theoretical analysis is presented for estimating the in-plane geometric nonlinear elastic stability behavior of steel members with tapered elements under dynamic loads. Beam-column approach is adopted for modeling the structural members as beam-column elements. The formulation is based on the Eulerian description taking into consideration the influence of axial force on bending stiffness. The changes in member chord length due to axial deformation and flexural bowing are also considered. In the dynamic analysis, the system mass properties have been represented using both lumped and consistent mass matrices. The consistent mass matrix is derived in three components: translational, rotational, and axial inertia. The formulation of the mass matrices in local and global coordinate systems of tapered members, which incorporates geometric nonlinearity, has been presented. A parametric study is conducted to examine the effects of number of tapered elements, tapering the prismatic members, time step size, and tapering ratio.

DYNAMIC ANALYSIS OF FRAMES WITH MATERIAL AND GEOMETRIC NONLINEARITIES BASED ON THE SEMIRIGID TECHNIQUE

2008 ◽  
Vol 08 (03) ◽  
pp. 415-438 ◽  
Author(s):  
F. T. K. AU ◽  
Z. H. YAN
Keyword(s):  
Dynamic Analysis ◽  
Stiffness Matrix ◽  
Plastic Hinge ◽  
Nonlinear Dynamic Analysis ◽  
Yield Condition ◽  
Computationally Efficient ◽  
Time Step ◽  
Geometric Nonlinearities ◽  
Frame Element ◽  
Sum Of Products

This paper presents a method for nonlinear dynamic analysis of frames with material and geometric nonlinearities which is based on the semirigid technique. The plastic hinge that accounts for the material nonlinearity is modeled as a pseudo-semirigid connection with nonlinear hysteretic moment-curvature characteristics at the element ends. The stiffness matrix of a frame element with material and geometric nonlinearities is expressed as the sum of products of the standard stiffness matrix and the geometric stiffness matrix of the element, with their corresponding correction matrices based on the plasticity factors developed from the section flexural stiffness at the plastic hinge locations. The combined stress yield condition is used for the force state determination of plastic hinges, and force equilibrium iterations and geometry updating for frames are carried out in every time step. When the key parameters of a structure are updated in a time step, the time step is split up into substeps to ensure accuracy while keeping the computations to a reasonable amount. The plastic rotation history can be calculated directly or in an approximate indirect way. The method is computationally efficient and it needs no additional connection elements, which makes it convenient for incorporation into existing linear dynamic analysis programs. Besides, the method can handle accurately and efficiently the dynamic analysis of nonlinear frames using relatively large time steps in conjunction with time step subdivision to cope with key parameter changes. A portal frame is used to verify the correctness of the proposed method. A more complicated five-story frame is used to illustrate the applicability and performance of the proposed method.

Effect of damage limit states on the seismic fragility of reinforced concrete frame-shear wall buildings

2021 ◽  
Vol 14 (9) ◽  
pp. 57-68
Author(s):  
Durga Mibang ◽  
Satyabrata Choudhury
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Analysis ◽  
Seismic Vulnerability ◽  
Design Method ◽  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Soil Condition ◽  
Shear Wall ◽  
Reinforced Concrete Frame ◽  
Limit States

Assessment of the seismic vulnerability of frame-shear wall buildings can be performed by non-linear dynamic analysis and it needs detailed analytical modeling, structural performance measures and various earthquake intensities. The codal based design method can hardly be used for designing buildings of pre-defined target objectives whereas the Unified performance-based design (UPBD) method can be designed for buildings of pre-defined target objectives. In the current study, the UPBD method for frame-shear wall buildings has been applied for different performance levels (PL) i.e. Immediate occupancy (IO), Life safety (LS) and Collapse prevention (CP) with 1%, 2% and 3% drift in both the directions of the buildings. The nonlinear dynamic analysis of the reinforced concrete (RC) frame-shear wall buildings is performed considering spectrum compatible ground motions (SCGM) as per EC-8 demand spectrum at 0.45g level and type B soil condition. Vulnerability assessment of the frame-shear wall buildings is conducted by generating fragility curves and the probability failure of structure is checked based on different configurations and damage limit states of the structure. Finally, the outcome of the work gives a proper idea of the nonlinear behavior of the dual system so that optimum design could be acquired for achieving higher safety aspects.

Comportement dynamique des lignes aériennes de transport d'électricité dû aux bris de câbles. II. Problèmes numériques associés à la modélisation mathématique

1989 ◽  
Vol 16 (3) ◽  
pp. 354-374 ◽  
Author(s):  
Ghyslaine McClure ◽  
René Tinawi
Keyword(s):  
Transmission Lines ◽  
Nonlinear Dynamic ◽  
Numerical Models ◽  
Equations Of Motion ◽  
Nonlinear Dynamic Analysis ◽  
Small Scale ◽  
Convergence Criterion ◽  
Direct Integration ◽  
Time Step ◽  
Integration Methods

The evaluation of the response of an aerial power line section subjected to cable breakage is a complex dynamic problem in which geometric nonlinearities are important. The solution of the equations of motion of the model calls for direct integration methods for which the stability and behavior, in nonlinear situations, are difficult to predict. Seven numerical models are analyzed with the Wilson-θ and the Newmark-β algorithms and results are compared with those of small-scale tests of the American Electric Power Research Institute. This comparison emphasizes the importance of the high frequency modes in the response and the artificial damping induced by the Wilson-θ method. This method allows up to three times the time increment required by the trapezoidal rule that does not filter the contribution of higher frequencies but is limited by a convergence criterion. Many observations made in this particular study are also applicable to multi-degree-of-freedom nonlinear dynamic problems using direct time-step integration. Key words: Nonlinear dynamic analysis, direct integration methods, aerial electric transmission lines, cable breakage simulation.

Nonlinear Dynamic Response of Membranes: State of the Art

1991 ◽  
Vol 44 (7) ◽  
pp. 319-328 ◽  
Author(s):  
Chris H. Jenkins ◽  
John W. Leonard
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Nonlinear Static Analysis ◽  
Fluid Structure Interactions ◽  
Membrane Structures ◽  
Field Equations ◽  
Surface Geometry ◽  
Large Rotation ◽  
Strain Type

Membrane structures have been used since the earliest of times. Until recently, their analysis has relied chiefly on trial and error; however, modern methods of analysis are evolving. The deformations are nearly always of the large rotation and/or strain type and are thus inherently nonlinear. Static analysis can be considered as a special case of the dynamic analysis. This paper is concerned then with reviewing methods of nonlinear dynamic analysis of membrane structures. Two problems of analysis are associated with membrane structures: (i) shape (or form) finding; (ii) response (deformation and/or stress) analysis. Shape finding (ie, determination of the surface geometry given an initial prestress, generation of cutting patterns, etc) is nontrivial but well documented in the literature and is not considered in this paper. In this review attention is instead focused on formulation of field equations, wrinkling analysis, fluid/structure interactions, material nonlinearities, and computational methods.

Coupled Motion Analysis of a Semisubmersible Platform in Campos Basin

2004 ◽  
Author(s):  
Francisco Edward Roveri ◽  
Marcos Vinicius Rodrigues ◽  
Breno Pinheiro Jacob
Keyword(s):  
Numerical Models ◽  
Nonlinear Dynamic Analysis ◽  
Coupled Analysis ◽  
Current Profile ◽  
Time Step ◽  
Frequency Spectra ◽  
Environmental Loading ◽  
Campos Basin ◽  
Loading Case ◽  
Platform Motions

This work describes the generation of numerical models for the coupled analysis of a semisubmersible platform to be installed in Campos Basin, and presents the results, in terms of platform motions, of a set of analyses under fatigue environmental loading cases. The coupled model comprises the hull, the mooring lines, and all risers connected to the platform. The model includes also a FSHR (Free Standing Hybrid Riser) system to be connected to the platform; this system is composed by a rigid riser, an air can and a flexible jumper. A set of environmental loading cases appropriate for fatigue analyses is defined, in terms of current profile, irregular bi-directional seastate, and wind. For each loading case, nonlinear time-domain dynamic analyses are performed employing the Prosim program. This program is based in a coupled formulation that incorporates, in a single code and data structure, a hydrodynamic model to represent the hull, and a finite element model to rigorously represent the structural/hydrodynamic behavior of the lines. At every time step of the time integration of the equations of motion representing the hull, a series of nonlinear dynamic analysis of the lines is performed following a subcycling procedure. The results of the coupled analysis are expressed as time histories of platform motions. The next step is to proceed to the treatment of these time series, in order to determine, for each loading case: a) The frequency spectra of each motion component; and b) Representative statistical values in terms of static offsets, first and second-order motions (standard deviations and periods for low-frequency and wave-frequency motions). The platform motions that result from the coupled analyses presented in this work can be employed to perform the detailed structural analysis of the FSHR system, by employing an isolated model of the riser in a specialized program.

Sign in / Sign up

Export Citation Format

Share Document