Seismic reliability assessment of classical columns subjected to near-fault ground motions

A methodology for the performance-based seismic risk assessment of classical columns is presented. Despite their apparent instability, classical columns are, in general, earthquake resistant, as proven from the fact that many classical monuments have survived many strong earthquakes over the centuries. Nevertheless, the quantitative assessment of their reliability and the understanding of their dynamic behavior are not easy, because of the fundamental nonlinear character and the sensitivity of their response. In this paper, a seismic risk assessment is performed for a multidrum column using Monte Carlo simulation with synthetic ground motions. The ground motions adopted contain a high- and low-frequency component, combining the stochastic method, and a simple analytical pulse model to simulate the directivity pulse contained in near source ground motions. The deterministic model for the numerical analysis of the system is three-dimensional and is based on the Discrete Element Method. Fragility curves are produced conditional on magnitude and distance from the fault and also on scalar intensity measures for two engineering demand parameters, one concerning the intensity of the response during the ground shaking and the other the residual deformation of the column. Three performance levels are assigned to each engineering demand parameter. Fragility analysis demonstrated some of the salient features of these spinal systems under near-fault seismic excitations, as for example, their decreased vulnerability for very strong earthquakes of magnitude 7 or larger. The analysis provides useful results regarding the seismic reliability of classical monuments and decision making during restoration process

Foreign Direct Investments, Regional Incentives and Regional Attractiveness in Greece

The aim of this paper is to analyze the Foreign Direct Investment (FDI) activity in Greece. The paper starts with defining the main FDI terms and giving a general literature review corresponding to the FDI allocation. Then, there is a description of recent trends in FDI activity both worldwide and Greece. Especially FDI investments in Greece are analyzed presenting the magnitudes of inflows, outflows, inward stock, outward stock, as well as foreign mergers and acquisitions, in terms of sales and purchases. The second part of the paper describes the regional and sectoral allocation of FDI in Greece, emphasizing whether the investment incentive scheme contributes to the attraction of FDI in specific regions, or the growth rate of each region is the main motive for locating foreign investment capital. The analysis is based on the most recent statistical data covering magnitudes until 2002.

Dynamic behavior of rocking structures allowed to uplift

Strong shaking of structures during large earthquakes may result in some cases in partial separation of the base of the structure from the sail. This phenomenon of uplifting, which can affect the dynamic behavior of the structure significantly, even if the amount of uplift is small, is examined in this thesis. First the case of a rocking rigid block is investigated and then more complicated, flexible superstructures are introduced. Two foundation models which permit uplift are considered: the Winkler foundation and the much simpler "two-spring" foundation. Several energy dissipating mechanisms are also introduced into these models. It is shown that an equivalence between these two models for the foundation can be established, so that one can always work with the much simpler two-spring foundation. In this way complete analytical solutions can be derived in most cases. Moreover, simple approximate methods for the calculation of the apparent fundamental period of the rocking system are developed and simplified methods of analysis are proposed. In general, uplift leads to a softer vibrating system which behaves nonlinearly, although the response is composed of a sequence of linear responses. As a result, the apparent fundamental resonant frequency of the uplifting system is always less than the fundamental resonant frequency of both the soil-structure interacting system, in which lift-off is not allowed, and the superstructure itself. The second and higher resonant frequencies of the superstructure, however, are not affected significantly by lift-off. For damped foundations, the ratio of critical damping associated with the apparent fundamental mode decreases, in general, with the amount of lift-off. These effects of uplift on the dynamic properties of the rocking system can alter the response of the structure significantly during an earthquake. Nevertheless, it cannot be said a priori whether they are favorable to the behavior or not; this depends on the parameters of the system and the time history of the excitation

Foreign Direct Investments, Regional Incentives and Regional Attractiveness in Greece

The aim of this paper is to analyze the Foreign Direct Investment (FDI) activity in Greece. The paper starts with defining the main FDI terms and giving a general literature review corresponding to the FDI allocation. Then, there is a description of recent trends in FDI activity both worldwide and Greece. Especially FDI investments in Greece are analyzed presenting the magnitudes of inflows, outflows, inward stock, outward stock, as well as foreign mergers and acquisitions, in terms of sales and purchases. The second part of the paper describes the regional and sectoral allocation of FDI in Greece, emphasizing whether the investment incentive scheme contributes to the attraction of FDI in specific regions, or the growth rate of each region is the main motive for locating foreign investment capital. The analysis is based on the most recent statistical data covering magnitudes until 2002

Upthrow of objects due to horizontal impulse excitation

The phenomenon of upthrow of rigid blocks, excited into motion by horizontal impulses, is examined in this study. A simple foundation model is used, consisting of two sets of springs and dashpots; one set near each corner of the block. Each set consists of vertical and horizontal elements. The vertical springs are not permitted to take tensile forces, so separation of the block from the ground is allowed. The associated horizontal spring separates along with the vertical spring. The response can be separated into three regimes, namely, full contact, partial uplift, and complete separation. Analytical expressions for the response are given for the first two cases; the third case is simply rigid body motion. The overall response is nonlinear and analytical criteria for upthrow were not found. The minimum value of the impulse required for complete separation, expressed as a normalized initial velocity, was determined numerically and a parametric investigation performed. Although the irregularity of the results does not allow many general conclusions to be drawn, it was found that for short blocks, a decrease in the stiffness of the horizontal foundation springs required larger impulses for separation. These effects had mixed results for tall blocks

The Salonica (Thessaloniki) earthquake of June 20, 1978

The 6.5 magnitude Salonica earthquake of June 20, 1978 is an earthquake of major interest from the engineering point of view, since it occurred near a city of 700,000 inhabitants. In general, the damage was not extensive and modern buildings performed quite well during the earthquake, while some old ones suffered severe damage. The author was on vacation in Athens at the time of the earthquake and visited Salonica on June 23rd. As the intention of this visit was to make a general survey of the affected area, detailed descriptions of the engineering features of the earthquake and the building damage are not included in this report

Seismic behaviour of the walls of the Parthenon: A numerical study

A numerical study of the behaviour of the walls of the Cella of Parthenon subjected to seismic loading is presented. Commonly used numerical codes for masonry structures based on continuum mechanics are unable to handle the behaviour of discontinuous walls of ancient monuments, in the same way as continuum models cannot capture the behaviour of drum-columns. In this analysis, the discrete element method was used, which has been proven, in previous research, capable to accurately predict the response of discontinuous structural systems. The marble structural stones of the walls were modeled as rigid blocks with fric- tional joints between them. Two types of models were used in the analyses: (i) a sub-assembly consisting of only a section of the wall of limited length, either as it is in-situ (partially col- lapsed) or with its full height (restored) and (ii) considering the whole structure partially re- stored. In one of the models of type (i), the existing damage of the stones was also implemented. Analyses were performed with and without considering the metallic elements (clamps and dowels) that connect adjacent stonesPart of the research presented in this paper was funded by the Committee for the Preserva- tion of the Acropolis Monuments (YSMA), which also provided the restoration scenario that was used for the full-structure model of Figure 3. Special thanks are due to A. Vrouva, civil engineer with YSMA and N. Toganidis, architect with YSMA, for their help with the con- struction details of the monumenPostprint (published version

Mononuclear lanthanide(III)-salicylideneaniline complexes: synthetic, structural, spectroscopic and magnetic studies

The reactions of hydrated lanthanide(III) [Ln(III)] nitrates and salicylideneaniline (salanH) have provided access to two families of mononuclear complexes depending on the reaction solvent used. In MeCN, the products are [Ln(NO3)3(salanH)2(H2O)]·MeCN, and, in MeOH, the products are [Ln(NO3)3(salanH)2(MeOH)]·(salanH). The complexes within each family are proven to be isomorphous. The structures of complexes [Ln(NO3)3(salanH)2(H2O)]·MeCN (Ln = Eu, 4·MeCN_Eu, Ln = Dy, 7·MeCN_Dy; Ln = Yb, 10·MeCN_Yb) and [Ln(NO3)3(salanH)2(MeOH)]·(salanH) (Ln = Tb, 17_Tb; Ln = Dy, 18_Dy) have been solved by single-crystal X-ray crystallography. In the five complexes, the LnIII center is bound to six oxygen atoms from the three bidentate chelating nitrato groups, two oxygen atoms from the two monodentate zwitterionic salanH ligands, and one oxygen atom from the coordinated H2O or MeOH group. The salanH ligands are mutually "cis" in 4·MeCN_Eu, 7·MeCN_Dy and 10·MeCN_Yb while they are "trans" in 17_Tb and 18_Dy. The lattice salanH molecule in 17_Tb and 18_Dy is also in its zwitterionic form with the acidic H atom being clearly located on the imine nitrogen atom. The coordination polyhedra defined by the nine oxygen donor atoms can be described as spherical tricapped trigonal prisms in 4·MeCN_Eu, 7·MeCN_Dy, and 10·MeCN_Yb and as spherical capped square antiprisms in 17_Tb and 18_Dy. Various intermolecular interactions build the crystal structures, which are completely different in the members of the two families. Solid-state IR data of the complexes are discussed in terms of their structural features. 1H NMR data for the diamagnetic Y(III) complexes provide strong evidence that the compounds decompose in DMSO by releasing the coordinated salanH ligands. The solid complexes emit green light upon excitation at 360 nm (room temperature) or 405 nm (room temperature). The emission is ligand-based. The solid Pr(III), Nd(III), Sm(III), Er(III), and Yb(III) complexes of both families exhibit LnIII-centered emission in the near-IR region of the electromagnetic spectrum, but there is probably no efficient salanH→LnIII energy transfer responsible for this emission. Detailed magnetic studies reveal that complexes 7·MeCN_Dy, 17_Tb and 18_Dy show field-induced slow magnetic relaxation while complex [Tb(NO3)3(salanH)2(H2O)]·MeCN (6·MeCN_Tb) does not display such properties. The values of the effective energy barrier for magnetization reversal are 13.1 cm−1 for 7·MeCN_Dy, 14.8 cm−1 for 17_Tb, and 31.0 cm−1 for 18_Dy. The enhanced/improved properties of 17_Tb and 18_Dy, compared to those of 6_Tb and 7_Dy, have been correlated with the different supramolecular structural features of the two families. The molecules [Ln(NO3)3(salanH)2(MeOH)] of complexes 17_Tb and 18_Dy are by far better isolated (allowing for better slow magnetic relaxation properties) than the molecules [Ln(NO3)3(salanH)2(H2O)] in 6·MeCN_Tb and 7·MeCN_Dy. The perspectives of the present initial studies in the Ln(III)/salanH chemistry are discussed

Seismic assessment, behavior and retrofit of heritage buildings and monuments

This book assembles, identifies and highlights the most recent developments in Rehabilitation and retrofitting of historical and heritage structures. This is an issue of paramount importance in countries with great built cultural heritage that also suffer from high seismicity, such as the countries of the eastern Mediterranean basin. Heritage structures range from traditional residential constructions to monumental structures, ancient temples, towers, castles, etc. It is generally recognized that these structures present particular difficulties in seismic response calculation through computer simulation due to the complexity of the structural system which is, generally, inhomogeneous, with several contact problems, gaps/joints, nonlinearities and brittleness in material constituents. This book contains selected papers from the ECCOMAS Thematic Conferences on Computational Methods in Structural Dynamics & Earthquake Engineering (COMPDYN) that were held in Corfu, Greece in 2011 and Kos, Greece in 2013. The Conferences brought together the scientific communities of Computational Mechanics, Structural Dynamics and Earthquake Engineering in an effort to facilitate the exchange of ideas in topics of mutual interest and to serve as a platform for establishing links between research groups with complementary activities