Gerasimidis, Simos
Loading...
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Assistant Professor
Last Name
Gerasimidis
First Name
Simos
Discipline
Civil and Environmental Engineering
Engineering
Engineering
Expertise
Introduction
Name
6 results
Search Results
Now showing 1 - 6 of 6
Publication Metadata only A computational model for full or partial damage of single or multiple adjacent columns in disproportionate collapse analysis via linear programming(2013-01-29) Gerasimidis, Simos; Bisbos, C.; Baniotopoulos, C.The evaluation of the sensitivity or insensitivity of structures to local damage has been a major research field during the last decades, mainly provoked due to the series of aging structures and infrastructures. Many researchers have described this property as redundancy, others as the resistance to disproportionate collapse or robustness and still others as the ability of structural systems to display alternate load paths in case of a local damage. In any case, the problem for the evaluation of this property is increasingly alarming since many systems experience similar collapses (American Society of Civil Engineers (2009). Proceedings of Structures Congress on the first international symposium on disproportionate collapse. ASCE, Austin, TX). This paper presents the numerical assessment of disproportionate collapse analysis introducing the concept of partial damage of structural elements. Global robustness measures are proposed also for the case of multiple partial losses of adjacent elements. The measures are computed on the basis of a mathematical optimization problem using collapse load analysis of steel frames with pre-existing damage. Results comparing the cases of partial losses with the full column lossesare presented and discussed.Publication Open Access Revised Load Rating Procedures for Deteriorated Prestressed Concrete Beams(2023-01) Stripsky, Alex; Brena, Sergio F; Boakye, Jessica; Civjan, Scott A; Gerasimidis, SimosThe first prestressed concrete bridge in the United States was built in the early 1950s. Since then, several typical sections have been developed for use in bridge construction including I-beams, deck slabs, box beams, double tees, etc. In bridges under aggressive environments, corrosion deterioration of prestressing strands and stirrups has occurred creating challenges associated with determining the strength of deteriorated existing bridge sections. The MassDOT LRFD Bridge Manual includes provisions to estimate strength of corrosion deteriorated prestressed concrete box beams allowing engineers to calculate the load rating of these types of bridges. The provisions are based on the observed condition of the bridge, particularly with regard to estimates of strand area reductions to estimate residual strength. In bridges with adjacent box beams or deck slabs, corroded reinforcement is difficult to identify because only the top and bottom surfaces of the superstructure elements are accessible. The goals of this research are to evaluate the existing strength calculation procedures and to provide recommendations on how to properly evaluate the reduction in strand area based on the observed condition of the bottom surface of the prestressed box or deck beams.Publication Metadata only Disproportionate Collapse Analysis of Cable-stayed Steel Roofs for Cable Loss(2011-03-13) Gerasimidis, Simos; Baniotopoulos, C.Disproportionate collapse has been identified lately as a real cause of failure for structural engineering projects. Rare and unexpected, the phenomenon of disproportionate collapse usually results to many fatalities and thus, its analysis and mitigation is deemed necessary. This work describes the analysis of a cable-stayed steel roof under the scenario of a cable loss. The eventof a cable loss is assumed to be brittle, while relevant recent recommendations suggest the application of a scaled equivalent static force at the points of the anchorage of the cable but in the opposite direction of the original cable force. In this paper, three different conditions have been considered in order to study the effect of the cable loss into the overall structural responseof a typical cable-stayed roof; the level of the equivalent nodal load in the opposite direction of the original cable force varies. The steel structure of the roof, in its complexity, closer to responding as a cable-stayed bridge rather than a steel roof provides a useful template for conclusions; several topics regarding disproportionate collapse and cable losses are discussed.Publication Metadata only Steel moment frames column loss analysis: The influence of time step size(2011-04) Gerasimidis, Simos; Baniotopoulos, C.This paper applies two well-known structural dynamics computational algorithms to the problem ofdisproportionate collapse of steel moment frames applying the alternate load path method. Any problem of structural dynamics strongly depends on the accuracy and the reliability of the analysis method since the parameters involved in the selection of the appropriate algorithm are affected by the nature of the problem. Disproportionate collapse is herein simulated via a time history analysis used to ‘‘turn off’’ the effectiveness of an element to the structure. For this kind of problem the time step size of the computational algorithm is of major importance for the accuracy of the method and thus, remains a variable throughout the present analyses. Two plane steel moment frames are used for the numerical examples, while all the analyses are performed independently. Firstly the β-Newmark method is applied and secondly the linear Hilbert–Hughes–Taylor a-method is applied and the respective results are compared and discussed in the last part of the paper.Publication Metadata only Evaluation of wind load integration in disproportionate collapse analysis of steel moment frames for column loss(2011-11) Gerasimidis, Simos; Baniotopoulos, C.The design of steel structures, in most cases, depends majorly on the level of wind loads which are prescribed by codes and regulations and are used in the structural analysis due to the fact that steel structures being light and ductile systems are strongly affected from a slight difference in the values of wind loading. During the last decades, disproportionate collapse analysis has become of major interest mainly due to the increasing number of failures occurring in that pattern. Commonly accepted guidelines and methods of analysis have been produced, the most dominating of which being the Department of Defense Facilities criteria or DoD. In the DoD, as well as in other criteria, the event of a column loss is suggested as modeling scenario which has to be sustained by a structural system in order to be robust. However, all the guidelines so far have disconnected the column loss analysis from wind loads and have only performed it for gravity loading. This paper presents the dynamic time history disproportionate collapse analysis of steel frames, including various levels of wind loading. Interesting aspects are discussed through the parametric analysis of five different numerical examples of moment resisting frames.Publication Metadata only Loss-of-stability induced progressive collapse modes in 3D steel moment frames(2014-03-21) Gerasimidis, Simos; Deodatis, G.; Kontoroupi, ThaliaThis paper deals with the progressive collapse analysis of a tall steel frame following the removal of a corner column according to the alternate load path approach. Several analysis techniques are considered (eigenvalue, material nonlinearities, material and geometric nonlinearities), as well as 2D and 3D modelling of the structural system. It is determined that the collapse mechanism is a loss-of-stability-induced one that can be identified by combining a 3D structural model with an analysis involving both material and geometric nonlinearities. The progressive collapse analysis reveals that after the initial removal of a corner column, its two adjacent columns fail from elastic flexural-torsional buckling at a load lower than the design load. The failure of these two columns is immediately followed by the failure of the next two adjacent columns from elastic flexural–torsional buckling. After the failure of these five columns, the entire structure collapseswithout the occurrence of any significant plastification. The main contribution is the identification of buckling-induced collapse mechanisms in steel frames involving sequential buckling of multiple columns. This is a type of failure mechanism that has not received appropriate attention because it practically never occurs in properly designed structures without the accidental loss of a column.