for their indispensable support and guidance during my doctoral period. Thanks to their confidence, the development and consecution of this thesis have been possible.I also wish to show my gratitude to my colleagues from Universitat Politècnica de València for the comforting moments which relieved the pressure of this constant work: Ana, Andrés and Toni, thanks for maintaining the same good atmosphere at the office as always. And thanks to the people from the Department of Construction Engineering and Civil Engineering Projects with whom I shared my beginnings: Héctor, Estefanía, Josemi, José Vicente, Juan and Vicente. Special thanks go to Ana Espinós for her wise advice in my first approach to concrete filled tubular columns and in every aspect of my career.Sincere gratitude goes to my new colleagues from Universitat Jaume I for their constant support even in the distance, especially to David and Roberto who have made easier this hard period.Another big thank you goes to Dr. Filippou for inviting me to join a leading institution as University of California at Berkeley during part of my doctoral period and for his assistance during my stay there since I had the incredible opportunity of collaborating and attending the master lectures of a referent in the field of nonlinear analysis of structures. I would like also to thank the encouragement received from all my friends during these years.Last of all, I would like to give special thanks to my family, in particular to my grandparents, parents and brother for their patience and understanding. This thesis has been possible thanks to you.

In order to study the mechanical response of concrete-filled steel tubular (CFST) columns, several experimental and theoretical studies have been conducted in the last years. However, the influence of thin-walled steel tubes on the axial capacity of these composite columns is not completely stablished, especially when it is combined with high-strength concrete as infill. In this paper, the results of an experimental campaign on 18 concretefilled steel tubular stub columns subjected to concentric load are presented. Different crosssection shapes are considered in this campaign, i.e. circular, square and rectangular. The influence of the steel tube wall thickness is analysed by including specimens with thinwalled tubes in the experiments, whose behaviour needs to be studied in depth given the issues arising when working under compression. The experimental program is designed so the analysis of the results permits to drawn consistent conclusions. For each series, the steel tube thickness is the only geometric parameter modified in order to properly study its effect. Besides, two different concrete strengths were considered for the concrete infill, i.e. normal and high-strength concrete, to observe their effect on the ultimate capacity of the columns. During the tests, the specimens are subjected to axial load and the evolution of the axial displacement with the load is registered. The ultimate capacity of each specimen is obtained and an analysis of the steel tube thickness and concrete strength influence is accomplished. Finally, the study of the dependency of the failure mode on these parameters is carried out.

Abstract:The use of games with educational purposes has a lot of benefits since it creates attractive scenarios for learning combining different techniques like rewards, competitions or challenges. Computer games as a teaching instrument have been very popular among educators in the last years. However, some difficulties may arise to find the appropriate game given the specific aims of each subject which is more remarkable in higher education. Besides, the current reduced education budgets have led lecturers to search for alternatives. Game boards can be a good option since they have a low cost and can be easily customized. In the present work, an experiment carried out with undergraduate students of mechanical engineering at the Universitat Jaume I (Castelló de la Plana, Spain) is described. A questions game board created by the students was used as a review tool. During the course, the students proposed questions to be incorporated to the game working in groups. In the last session it was used in an organized competition among the students. Working in groups enhances communication and collaboration whereas using the elaborated game as a review tool help to summarize and reinforce essential concepts. In general, students were very interested and motivated to acquire new knowledge.

Abstract

In the past, many works to study the mechanical behaviour of concrete filled steel tubular (CFST) stub columns have been conducted. Some of the applications of these composite columns oblige to meet higher requirements of ductility and load-bearing capacity. Traditionally, circular and rectangular tubes have been employed but recently new cross-sectional shapes of these composite columns are being designed and investigated with the aim of optimizing their mechanical behaviour. In this line, concrete-filled round-ended steel tubular columns (CFRT) have appeared as an alternative. However, the number of experimental programs to characterize their mechanical response is still scarce. In order to contribute to the test results database, in this paper an experimental study of 9 concrete-filled round-ended steel tubular stub columns is presented. All the specimens were designed with the same cross-sectional round-ended shape and have the same dimensions. In this program, both normal and high-strength concrete were employed as infill. During the tests, the columns were subjected to axial compression loads but under different eccentricities. The influence of eccentricity and concrete strength on the ultimate load bearing capacity of the concrete-filled round-ended steel tubular are discussed. Besides, the combined action of both components in this type of concrete-filled tubes as well as the effect of the concrete infill are studied.