The uneven distributions of mass and stiffness in the case of multi-storey concrete buildings lead to a torsion sensitivity of those civil structures under dynamical loadings like earthquakes or wind and gusts. In order to minimize the overall torsion, it is imperatively necessary to reduce the distance between the centre of mass (CM) and centre of stiffness (CS) in the design stage. In this context, the main purpose of this paper is to present a theoretical method of reducing torsion by minimizing the distance between CM and CS at the level of each floor of the structure. Principal stiffness axes are also changed in convenient directions so that the movement of the structure leads to a favourable plastic mechanism in the fundamental mode of vibration. To achieve the goal, the main objective is to change the dimensions and orientations of the pillars located on the perimeter of the structures. The described method was used to study: irregular shaped structures in plan; structures with stairs or with central concrete core; structures with elevation retractions. The overall torsion reducing was achieved with Matlab programs, and the verification of the results was carried out by using the software ETABS 2016.

As hybrid carbon-aramid composites become widely used in various industries, it has become imperative to mechanically characterize them using accurate methods of measuring the entire deformation field such as the digital image correlation (DIC) method. The accuracy of the numerical simulation of carbon-aramid composite structures depends on the accuracy of the elastic constants. Therefore, the goal of this research is to model and simulate the mechanical behaviour of the composite based on epoxy resin reinforced with carbon-aramid woven fabric by considering the mechanical properties investigated by tensile test combined with DIC and the bending test. The curves of the transverse strains related to the longitudinal strains were investigated using DIC in order to determine the Poisson’s ratios in the case of tensile tests applied in warp or weft directions of the reinforcement fabric. The impact strength determined by Charpy tests is also reported. The other main objective is to use the analytical models to compute the tensile and flexural moduli of elasticity for the fictitious orthotropic materials which behave similarly to the carbon-aramid composite investigated. The simulations regarding the behaviour of the carbon-aramid composite in tensile and bending tests were validated by the experimental results, since the maximum errors recorded between experimental and theoretical results were 0.19% and 0.15% for the equivalent tensile modulus and for the equivalent flexural modulus, respectively.

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.