Radan Ivanov

Radan Ivanov
National Institute of Geophysics Geodesy and Geography - Bulgarian Academy of Sciences · Seismology and Seismic Engineering

Ph.D.

About

77
Publications
1,102
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45
Citations
Citations since 2017
17 Research Items
28 Citations
201720182019202020212022202301234567
201720182019202020212022202301234567
201720182019202020212022202301234567
201720182019202020212022202301234567
Introduction
Seismic risk of underground pipelines. Seismic strong-motion networks

Publications

Publications (77)
Article
Full-text available
Transient wave processes in viscoelastic structures built from functionally graded material (FGM) still remain almost unexplored. In this article, the problem of the propagation of nonstationary longitudinal waves in an infinite viscoelastic layer of a FGM with plane–parallel boundaries is considered. The physical and mechanical parameters of the F...
Article
Full-text available
A problem of non-stationary longitudinal wave propagation in the cross-section of an infinite hollow linear-viscoelastic cylinder with coaxial elastic inclusion is considered. On the contact surfaces between the layers, continuity of displacements and stresses is assumed. The solution of the problem is constructed using the integral Laplace transfo...
Conference Paper
Full-text available
In this work, an analytical solution of the P-wave propagation through a viscoelastic layer subjected to a smoothed-step pressure applied on the surface, is compared to the solution of the same problem obtained by FE simulation using explicit dynamic analysis. Viscoelasticity is introduced by either a regular or singular relaxation kernel. Time-his...
Conference Paper
Full-text available
Materials exhibiting hereditary properties are widely used in modern technology. In this work, an analytical solution of the P-wave propagation through a viscoelastic layer subjected to a triangular stress pulse applied on the surface, is compared to the solution of the same problem obtained by a FE simulation using explicit dynamic analysis. It is...
Conference Paper
p>Damage Mechanics is employed to simulate the crack initiation and propagation in concrete structural elements. To this end, the stress-strain relationship for concrete is modified by introducing a damage variable which affects the elasticity tensor. The damage-based constitutive relationship defined for concrete is integrated into a general-purpo...
Conference Paper
p>This contribution focuses on the numerical modelling and simulation of the mechanical behaviour of structural elements containing a self-healing agent. Specifically, the finite element modelling of the mechanical response of plain concrete structural element, containing a healing agent and subject to various loading conditions is discussed. A cus...
Article
Full-text available
This paper presents a virtual experiment on the behaviour of a self-healing material from the family of cement-based composites, that contains a healing agent. A numerical model of a specimen made of a cement-based material, and containing a healing agent is subjected to the loading configuration of the four-point bending test, whereby the forces a...
Article
Full-text available
The construction of chimneys of solid bricks in buildings with sloped roofs was commonplace in Bulgaria for almost a century. The collapse of a chimney during an earthquake could potentially lead to damages greatly exceeding the loss of the chimney itself, e.g. partial damage to the roof tiling and leaks, as well as material damage, injury or loss...
Conference Paper
Full-text available
The paper presents the rehabilitation project for the movable bridge in Varna, following its failure in 1975. The existing old bridge is designed and built by the "MAN" company in 1939. In 1975 the movable part and one from the stationary parts of the bridge was completely destroyed by a ship accident. The reconstruction included installing new sup...
Conference Paper
ABSTRACT An earthquake of magnitude 5.6 Mw hit Western Bulgaria, on May 22, 2012. Its depth was 9.4 km, epicenter coordinates 42.66° N 23.01°E; maximum intensity MM VII. The source area of the earthquake is analysed, as well as observed damages to the building stock. The maximum ground velocity (PGV) distribution is presented. The strain distribu...
Article
Full-text available
In the year 1974 the Minicipality of Sofia approved the city plan containing the intention to build a metro system in Sofia. The construction works commenced in the year 1982. The route for Sofia metro Line- 1 Extension Project from Sveta Nedelya Square to Vassil Levski Stadium was financed with a loan from Japan International Cooperation Agency(JI...
Article
Full-text available
This paper investigates the behavior of polyvinyl chlo- ride and ductile iron pipelines in relation to surface fault displacements using the Discrete Element Method (DEM) and proposes a method to estimate the allowable fault displacements. When modeling pipes and joints, the nonlinear material properties and joint characteristics (allowing detachme...
Conference Paper
Paper addresses the behavior of polyvinyl chloride and ductile iron pipeline due to fault displacement by Discrete Element Method (DEM) and an estimation method of allowable fault displacement. In modeling of pipe and joint, nonlinear material properties and nonlinear joint characteristics (allowing detachment at joint) are considered. Under the se...
Conference Paper
A comprehensive numerical method for limit state simulation of buried jointed pipelines is presented. The pipe body is modelled by line elements and plastic deformation within it considered by plastic hinges. The basic mechanical properties of all common pipe joints e.g. stiffening in compression, detachment in tension, fracture in bending can also...
Article
The situations where the shear connection in a composite beam of steel and concrete can be subjected to concentrations of shear flow are listed and discussed. An account is given of relevant finite element (FE) analyses. The design rules given in the draft Eurocode for composite bridges, ENV 1994:2, for shear connection near anchorages of prestress...

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Projects

Projects (2)
Project
he available data for the water supply system in Pernik will be gathered in details and multi-layered presented and analysed in GIS format, different models will be applied to estimate the damages from deterministic seismic event (map of distribution of PGV) with magnitude and characteristics of the earthquake of 22 May 2012 near Pernik. The observed damages will be compared with the calculated ones.