Search results for "Ground motion"

Solutions for the Design and Increasing of Efficiency of Viscous Dampers

2016

In last decades many strategies for seismic vulnerability mitigation of structures have been studied and experimented; in particular energy dissipation by external devices assumes a great importance for the relative simplicity and efficacy. Among all possible approaches the use of fluid viscous dampers are very interesting, because of their velocity-dependent behaviour and relatively low costs. Application on buildings requires a specific study under seismic excitation and a particular attention on structural details. Nevertheless seismic codes give only general information and in most case the design of a such protection systems results difficult; this problem is relevant also in Italy whe…

Effect of steel collars on the seismic behaviour of axially-cracked historical stone columns

2014

Granite and heavy stone circular columns could often be found in the cultural heritage among ancient churches and historical buildings in all the Mediterranean area. Their good strength properties allow them to carry big load values, while their bright colours and aesthetical characteristics were used by a lot of architects in the past to achieve structural solutions with great visual impact.Though such materials have great compressive strength values, environmental effects, especially long term effects, can damage the structural members, by cracking them. In this way the slenderness of the column increases, and the presence of an imposed ground motion can be very dangerous, since the colum…

Earthquake ground motion artificial simulations through Fractional Tajimi-Kanai Model

2013

Fractional Tajimi–Kanai model for simulating earthquake ground motion

2014

The ground acceleration is usually modeled as a filtered Gaussian process. The most common model is a Tajimi–Kanai (TK) filter that is a viscoelastic Kelvin–Voigt unit (a spring in parallel with a dashpot) carrying a mass excited by a white noise (acceleration at the bedrock). Based upon the observation that every real material exhibits a power law trend in the creep test, in this paper it is proposed the substitution of the purely viscous element in the Kelvin Voigt element with the so called springpot that is an element having an intermediate behavior between purely elastic (spring) and purely viscous (dashpot) behavior ruled by fractional operator. With this choice two main goals are rea…

Nonlinear Response of RC Structures: Statistical Effects of Artificial Ground Motions

2020

The selection of seismic inputs for nonlinear dynamic analysis is widely debated, mainly focusing on the advantages and disadvantages provided by the choice of natural, simulated or artificial records. However, most of the available technical codes do not provide always the same suggestions and well-defined procedures for the generation of artificial ground motions. Considering that the strategy of the generation of accelerograms makes some doubts raise about the possible effect on the structural response, the work aims to investigate on the differences of the structural behavior by using accelerograms nominally equivalent but different in terms of stationarity. This paper presents a compar…

Deriving Seismic Surface Rotations for Engineering Purposes

2006

Random Vibrations of Structures under Propagating Excitations

1995

The problem of vibrations of structures under incoherent or, in particular, propagating excitations is important for large, extended civil engineering structures like bridges, lifelines, dams, offshore structures or for aircraft structures. In seismic engineering spatial ground motion models have been studied for more than a decade but credible, stochastic characteristics are available only since SMART-1 accelerograph array is in operation at Lotung in Taiwan.

G-CLASS: geosynchronous radar for water cycle science – orbit selection and system design

2019

The mission geosynchronous – continental land atmosphere sensing system (G-CLASS) is designed to study thediurnal water cycle, using geosynchronous radar. Although the water cycle is vital to human society, processes on timescalesless than a day are very poorly observed from space. G-CLASS, using C-band geosynchronous radar, could transform this. Itsscience objectives address intense storms and high resolution weather prediction, and significant diurnal processes such assnow melt and soil moisture change, with societal impacts including agriculture, water resource management, flooding, andlandslides. Secondary objectives relate to ground motion observations for earthquake, volcano, and subs…

A Non-stationary Fractional Tajimi Kanai Model of Earthquake Ground Motions

2013

Rockburst induced ground motion—a comparative study

2004

Abstract While rockbursts from underground copper mining in Western Poland normally produce surface peak ground accelerations (PGA) and velocities of 0.05–0.1 g and 1–3 cm/s, occasionally these peak motions may exceed 0.15 g and 10 cm/s, respectively. These larger motions are of considerable concern and an investigation has been undertaken to define the nature of these larger induced ground motions. This paper compares these rockburst motions with low intensity earthquakes. Various strong motion parameters such as PGA, peak ground velocity (PGV) and displacements as well as strong motion duration, Arias intensity, Fourier and response spectra are compared with those from earthquakes. It is …