Structural expressionism resembles the use of slender structural elements, in particular beam-type elements. To satisfy structural, functional, and also architectural requirements a comprehensive structural analysis must be performed. The main issue of this study is the buckling analysis of beam-type elements, concerning Cavalieri’s principle. The present study is divided into two separate sections. The first part is a theoretical study, in which a variable cross-section beam-type element is modeled. The stability analysis is performed by an indirect variational method and the stiffness of the support connections is also introduced. The numerical simulation highlights 6 cases defined by the restraints of the support connections. The case study follows the modification of the critical buckling load of the variable cross-section beam-type element. Prior to the case study, a novel verification method is proposed to achieve a realistic cross-section for the beam-type element. The study revealed that with ideal characteristics of the stiffness coefficients of the restrains significant increase of the critical buckling load is obtained, and further if an actual situation is considered with finite values of the stiffness of the restrains, the variable cross-section for the beam-type element is a recommended and rational choice to make, to eliminate stability issues.

In current design practice, typical seismic design of bridges tends to use simplified approaches. On the opposite side, the most advanced seismic analyses currently used in practice in all the fields of structural engineering are probably the ones used for the design of nuclear facilities, which include soil–structure interaction and motion incoherency effects. From that category, the most modern methodology is the probabilistic approach, which has been added to the new ASCE 4 standard. This type of state-of-the-art analysis is carried out in ACS SASSI software on a typical concrete bridge structure with deep foundations. A comparison of the results with the deterministic SSI approach and the typical Eurocode design from previous studies is presented at the end. Major differences in behavior are highlighted, which impact the overall safety of the structure.

The objective of the project was the rehabilitation and expansion of one bridge, located on the DN28 (a national road) in Sarca, Iasi County. The solution includes an atypical use of the flexible galvanized steel structure. The main challenge in this case was to finish the works without any traffic interruption on this section of the national road, as well as the assembly of the said corrugated steel structure under the existing bridge. The work was executed in record time and with reduced costs in comparison with the classic alternative solutions, such as concrete bridges. The paper highlights practical aspects from the key moments of the project and presents the major challenges and how they were solved for both the design and the construction stages.

The paper presents a seismic SSI study that has been conducted for a 242 m long concrete bridge in Braşov, that has deep foundations on drilled piles. The structure is typical for Romania and highly used throughout the country. The seismic soil-structure interaction were performed using the state-of-the-art ACS SASSI software. The soil-structure interaction analyses were performed for both coherent (synchronous) and incoherent (non-synchronous) seismic inputs. The main focus of the study is to evaluate the effects of soil – structure interaction and of the seismic motion incoherency on the bridge dynamic response. The paper includes comparisons of results obtained using the Eurocode 8 analysis procedures and the state-of-the-art seismic soil-structure interaction analysis using ACS SASSI. The final conclusions indicate the limitations of the current bridge design soil-structure interaction modelling and the simplified motion spatial variability modelling in Eurocode 8. Furthermore, the future directions of the research study are presented.