Student Projects

The dissertation is composed of three major parts. The first part is the theoretical research, which has as objective to provide in a combinatorial and simultaneously harmonic way, all the required information collected after the studying of various sources that the reader would require to comprehend in order to understand the software based analysis, application and results of structural repair methods in an earthquake damaged structure that follows in the second part. . It should also be noted that the repair methods chosen to be analyzed in the theoretical research, are the ones covered by the software (shotcrete, epoxy resins, FRP composite materials).

The second part includes the first stage of the software analytical component of the dissertation. With the aid of the professional design software Master 10 EC Fespa which operates primarily based on the latest editions of Eurocodes, an appropriate selected RC building located in an area with high and frequent seismic will undergo repair design analysis. At this stage the analysis will contain: i) the graphically representation of the building in the software, ii) the identification and fault type classification assignment on each of the building’s harmed elements iii) non-linear static (pushover) analysis to estimate the pre-repair structure behavior comparing the earthquake response of the building with the seismic stresses of the area, iv) the selection of the appropriate repair method for each hurt element.

The third major part contains the second stage of the software analysis. All the building data are inputted, the re-design of the under repair elements using the specified methods is taking place, and results regarding the new repaired elements design properties are generated. These properties are compared with the ones of their pre-repair state, and the significance of the findings are discussed. Finally the repaired now building will undergo pushover analysis again, so that it will be possible to compare and comment the pre-repair and post-repair behavior state, and to determine the effectiveness of the selected repair methods.

After a research like this, a wealth of theoretical information and software analysis outcomes are obtained, which in combination with personal knowledge and experience, that may be achieved after extensive study of literature, regulations and directives, could aid to the selection of an appropriate repair material and implementation method in order to achieve the maximum possible restoration-repair successfulness of the critical property (e.g. shear, bending moment) of each earthquake damaged structural element.

Firstly, are presented the basic principles of valuation and rehabilitation according to Eurocode 8 and a brief description of the three Limit States. In particular, reference is made to the type and the systems collecting the required data and information relating to the building under study, the range and the accuracy of which define the so-called «Knowledge Level». Afterwards, the allotted methods of analysis of the structure before and after the procedure, while the non – linear static analysis as provided in Eurocode 8, is covered in detail. Finally, a reference is made to the entire control logic of limit states under their respective acceptance criteria as described in Part 3 of Eurocode 8, for the assessment competence of the body.

Thereafter, the building and its analysis model are thoroughly described. Particular emphasis is given to simulate the inelastic behavior of critical sections of the structural elements.

Furthermore, presented the analysis of the building with the non-linear static procedure of Eurocode 8, in order to make the assessment of the building resistance for the target design, which corresponds to performance Level “Significant Harm’, for seismic activity with 10% probability of exceedance in 50 years. The results indicate a need to strengthen a large number of beams of the building, in order to increase their flexural strength, and also a failure from a large number of walls and several columns.

For this purpose, was chosen both the strengthening of beams with fiber wrap overlays throughout their length and also the strengthening of vertical elements with a concrete sealing and construction of new walls in some panels of the body throughout its height. Moreover, an increase of the bearing capacity of the foundation by adding piles is required. Furthermore, the analysis of the reinforced body to assess the resistance of the building for the same objective planning with the incumbent is presented.

Finally, all data, assumptions and results of the analysis both at the stage of the valuation, and the rehabilitation are presented and discussed thoroughly, fully detailed for each phase of the concerned institution. Also there is a reference made to some useful conclusions relating to non-Linear Structural Analysis and arising during their implementation in practice.

Furthermore, the essay studies the effect of the value of behavior factor “q” upon the overall actual cost of concrete building structures. For this purpose several case studies of concrete building models are analyzed with static system variations between frame system and coupled wall system. On those building models analysis for various values of the behavior factor “q” is applied, starting from the minimum value of “q“ = 1,5 to the maximum allowable value of “q” depending on the seismic Regulation respectively. The results of the measurements of the analysis show a noticeable clear decrease of the initial building structures expenditure, specifically on building structures designed for larger values of the behavior factor “q” compared to those designed for smaller values.

In conclusion, an inquiry of the application of non-linear static analysis “Push-over” for the inspection or the reconsideration of the values of the multiplication factor αu/α1, according to which is in many cases the behavior factor “q” on building structures is determined based on the Eurocode EC8, part 1. For this purpose a framework of parametric analysis has been planned, wherein a series of non-linear “Pushover” analyses has been implemented with the use of technical software on a number of different cases as a result of the variation of a series of parameters, such as height, geometry of the floor plan (length/width ratio) and the relationship of geometrical stiffness of columns and beams.