This special issue of U. Porto Journal of Engineering includes a selection of papers that were presented at the Symposium on Civil Engineering held during the 1st Doctoral Congress in Engineering (DCE 2015). A set of very interesting papers were presented at that session and their authors were invited to submit an extended version of their papers for inclusion in a special issue of this journal. After the reviewing process five papers have been selected covering mainly two different topics: transport infrastructures and structural dynamics and seismic analysis. The first topic is raised in an interesting paper entitled Freeway geometric design comparison between Mexico and Portugal. The second is brought up in four papers which cover very important and updated subjects, such as structural analysis, seismic loading characterization and losses’ estimation. All papers selected include original contributions and I´m strongly convinced that they will be a very interesting tool for the study of the referred subjects. Finally, I would like to congratulate all authors of the published papers and emphasize that the main objectives of this congress have been achieved, namely in what concerns the training process of the students enrolled in the Doctoral Program in Civil Engineering at FEUP.

The angle of seismic excitation has been proven to be an important factor when analysing the 3D behaviour of buildings. However, modern earthquake-related standards only cover partially the effects of this factor and practicable results of relevant studies are still limited. The proposed paper focuses on the determination of the critical angle of incidence based on the building's structural characteristics. An analytical expression is developed to define the critical angle for the case of single storey buildings and a special category of multi storey buildings under constant lateral forces assuming linear elastic behaviour of the structures.

Freeways typify accessibility, which is a parameter related to the development of a country. A developing country, such as Mexico, is concerned with an emergent construction market of freeways, which has been a target for Portuguese construction companies since the Portuguese economic and construction crisis in 2008.
In the earlier stages of a freeway project, the ubiquitous use of software calculations along with geometric standards restrictions is performed automatically and may introduce loss of sensitivity to the designer.
This paper addresses this concern by presenting a Standards comparison between Mexico and Portugal, focusing on the elements of design and a comparative multi-criteria analysis adapted from Kalamaras et al. (2000). Through six case studies, this paper analyses the Standards’ influence on the horizontal alignment outcome, the radial uncompensated accelerations and the Brückner curves, concluding with the multi-criteria analysis results.

This paper presents a methodology for the appropriate treatment of variability in the process of building vulnerability assessment. Material, geometric and mechanical properties of the assessed building typologies are simulated through a Monte-Carlo sampling procedure in which the statistical distribution of the latter parameters are taken into account. Record selection is performed in accordance with conditional hazard-consistent distributions of a comprehensive set of intensity measures, and matters of sufficiency, efficiency, predictability and scaling robustness are envisaged in the presented framework. Several intensity measures (IMs) are conjugated in the evaluation of building fragility and vulnerability, whereby fragility functions are established as the multivariate distribution of joint probability of being in a sequential set of damage states. Vulnerability Functions consequently determined provide not only a mean Damage Ratio per level of seismic intensity, but rather probabilistic distributions of Damage Ratio that reflect the ground motion variability expected as the interested site; as determined by the hazard-consistent conditional distribution of a set of sufficient intensity measures.

Industry plays a key role in the economy of a country, people welfare and socio-economic resilience to natural disasters. Earthquakes are known to have damaging impacts on industrial property and activity, oftentimes resulting in costly structural and non-structural losses to industrial buildings, business closure, production failure and job losses. Notwithstanding this fact, the industrial building stock has been continuously excluded from seismic risk models developed for Portugal as it is usually assumed that industrial buildings are expected to withstand strong earthquakes due to their lightweight and design governed by wind loads. The aim of this paper is thus to give a first contribution to the assessment of the seismic vulnerability and property losses of the existing Portuguese industrial steel building stock. Both losses to structural and non-structural components and industry-specific contents, such as production equipment and machinery, are taken into account. The expected direct industrial property losses for a probability of exceedance of 10 % in 50 years for mainland Portugal are herein estimated.

This study involves the applicability of a simplified modeling technique to simple-span slab-girder skewed bridges for dynamic analysis, based on grillage modeling strategies. To evaluate the applicability of this technique, skew angles ranging from 0° to 60° are studied. The ability to capture vibration modes of grillage models is compared with three-dimensional (3-D) finite element (FE) models, using shell and frame elements. The effect of the skew angle in the grillage modeling technique of the bridge's deck and the grillage model accuracy associated with the orientation of the transverse grillage members (TGMs) are studied. The grillage modeling technique eliminates shell elements to model the slab, reducing the number of degrees of freedom and the computational time in the bridge model, but, although its simplicity, demonstrates good ability to capture the vibration modes.