scholarly journals Analysis of damping ratio on the optimization of geometrically nonlinear truss structures subjected to dynamic loading

2020 ◽  
Vol 19 (3) ◽  
pp. 321-334
Author(s):  
Élcio Cassimiro Alves ◽  
◽  
Larissa Bastos Martinelli ◽  
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Loading ◽  
Geometric Nonlinearity ◽  
Numerical Models ◽  
Damping Ratio ◽  
Nonlinear Dynamic Analysis ◽  
Truss Structures ◽  
Geometrically Nonlinear ◽  
Cross Sectional ◽  
Updated Lagrangian

The objective of this paper is to present the formulation for optimizing truss structures with geometric nonlinearity under dynamic loads, provide pertinent case studies and investigate the influence of damping on the final result. The type of optimization studied herein aims to determine the cross-sectional areas that will minimize the weight of a given structural system, by imposing constraints on nodal displacements and axial stresses. The analyses are carried out using Sequential Quadratic Programming (SQP), available in MATLAB’s Optimization Toolbox™. The nonlinear finite space truss element is defined with an updated Lagrangian formulation, and the geometrically nonlinear dynamic analysis performed herein combines the Newmark method with Newton-Raphson iterations. The dynamic analysis approach was validated by comparing the results obtained with solutions available in the literature as well as with numerical models developed with ANSYS® 18.2. A number of optimization examples of planar and space trusses under dynamic loading with geometric nonlinearity are presented. Results indicate that the consideration of damping effects may lead to a significant reduction in structural weight and that such weight reduction is proportional to increases in damping ratio.

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.

Nonlinear Dynamic Analysis of Flexible Riser Structures

2008 ◽  
Author(s):  
S. A. Hosseini Kordkheili ◽  
H. Bahai
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Three Dimensional ◽  
Nonlinear Dynamic Analysis ◽  
Linearization Method ◽  
Element Formulation ◽  
Large Rotation ◽  
Pipe Elbow ◽  
Lagrangian Finite Element ◽  
Updated Lagrangian

An updated Lagrangian finite element formulation of a three-dimensional pipe elbow element is presented for large displacement and large rotation dynamic analysis. In this formulation a particular linearization method is used to avoid inaccuracies normally associated with the linearization schemes. The formulation has been implemented in a nonlinear finite element code and the results are verified. It is shown that the proposed formulation generates improved results over those previously reported in the literature.

scholarly journals Damage control of a twin-column pier with a replaceable steel shear link in a cap beam under transverse seismic motion

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Weiting Chen ◽  
Xuemeng Bai ◽  
Tengfei Xu ◽  
Shanshan Ke ◽  
Kailai Deng ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Damage Control ◽  
Damping Ratio ◽  
Compressive Strain ◽  
Nonlinear Dynamic Analysis ◽  
Compressive Load ◽  
Reinforced Concrete Column ◽  
Structural Dynamic ◽  
Shear Link

AbstractThis paper proposes a novel twin-column pier with a steel shear link (SSL) installed in the cap beam to reduce seismic damage in the transverse direction. The SSL interrupts the rigid cap beam and relieves the coupled deformation of the two columns. Benefits of the yieldable SSL in the event of a strong earthquake are the longer effective deformation of a column and limited axial compressive load. A benchmark reinforced-concrete bridge is employed in a seismic performance evaluation to verify the damage reduction performance of the novel twin-column pier with an SSL. Five numerical models, calibrated in a physical component test, are built in ABAQUS; that is, one original bridge and four novel bridges with different SSLs and accompanying configurations. Modal analysis shows that introducing the SSL does not change the overall structural dynamic characteristics. The nonlinear dynamic analysis results indicate that adopting the SSL effectively reduces the peak compressive strain of the reinforced-concrete column, but energy dissipation from the SSL is negligible compared with the total inputted seismic energy. There is no evident change in the macro seismic response of the twin-column pier when using the SSL, such as overall drift and structural damping ratio. Moreover, a transverse continuous main girder is suggested for realizing an additional restoring moment at the column top, which further reduces compressive strain.

Sign in / Sign up

Export Citation Format

Share Document