This study investigated the structural response of segmental tunnel linings to tunnel-boring machine (TBM) advance during the construction of a typical tunnel built in Mexico. Because of the thrusting of the TBM during excavation, an axial load acts along the longitudinal axis of the tunnel. This axial load decreases as the TBM advances away from the tunnel lining. However, the residual axial load continues acting on the lining, producing a coupling between rings that affects the structural response of the tunnel. In this paper, this effect is studied by means of finite-element models. A nonlinear parametric study was carried out in which the material properties, the influence of the number of rings, the residual axial load, and the position of continuous joints were examined. The numerical models were calibrated with (lab-based) experimental results obtained from the literature on a typical tunnel built in Europe. It was concluded that the residual load increases the structural capacity of the lining. Also, the study showed that the collapse mechanism was modified by the coupling between rings. Rings will fail by excessive deformations with less coupling, while with greater coupling, the collapse mechanism is caused mainly by cracking in the segments. Therefore, it is necessary to consider the effect of the TBM advance to evaluate the structural response of a segmental tunnel better.

The construction of tunnels has become increasingly common in city infrastructure; tunnels are used to connect different places in a region (for transportation and/or drainage). In this study, the structural response of a typical segmental tunnel built in soft soil was studied using a simplified model which considers the coupling between segmental rings. From an engineering point of view, there is a need to use simple and reliable finite element models. Therefore, a 1D model based on the Finite Element Method (FEM) composed of beam elements to model the segments and elastic-linear springs and non-linear springs to model the mechanical behavior of the joints was performed. To validate the modeling strategy, the numerical results were compared to (lab-based) experimental results, under an Ultimate Limit State, obtained from the literature, and a comparison between numerical results considering a 3D numerical complex model which included the nonlinearity of concrete, reinforcing steel and the joints was performed. With this simplified model, we obtained a prediction of approximately 95% of the ultimate loading capacity compared to the results developed in the experimental and 3D models. This proposed model will help engineers in practice to create “rational” structural designs of segmental tunnel linings when a “low” interaction between rings is expected.

Increased temperature due to global climate change is increasing the magnitude and frequency of extreme winds making billboard structures more vulnerable. This paper proposes a methodology to determine the structural safety of flexible outdoor single-post billboards. A CFD model of a flexible single-post billboard was performed as an example. Resultant wind forces were obtained for the previous model using different wind speeds. A mechanical numerical model of the billboard was realized, and this was subjected to the resultant wind forces. Internal forces for the most vulnerable places of the billboard were obtained for all different adopted wind speeds. Next, a reliability analysis of the billboard was performed considering several values for the bias factor and coefficient of variation for the internal forces caused by wind. Safety levels determined from the reliability analysis indicate that a billboard designed with a nominal wind speed of 180 km/h cannot achieve the target probability index of 3.2 for wind speed higher or equal to 200 km/h for any of the adopted probabilistic parameters. Significant differences in the found safety levels for the evaluated probability parameters indicate that billboard structures could undergo safety values below the target one with changes in the case where wind characteristics endanger this type of structure.

The aim of the research reported in this paper was to evaluate the recommendations commonly used for limiting the deformations of segmental reinforced concrete tunnels built in soft soil. These traditional deformation limits are empirical and do not consider the slenderness ratio or soil-pressure distribution around tunnels. Furthermore, while they are generally assumed to relate to the serviceability limit state, this is not clear. Parametric analyses were therefore performed by means of finite-element models in which the non-linear behaviour of joints and materials was taken in account. The serviceability deformation was defined to prevent typical problems that could jeopardise the serviceability states of segmental linings. These serviceability deformations were then compared with traditional deformation limits. The results showed that the serviceability deformation depends on the slenderness ratio and the soil-pressure distribution. It was concluded that empirical recommendations are only suitable for certain slenderness ratios and soil-pressure distributions.

In Mexico adobe masonry is a traditional building material common in rural areas with low economic development and a high degree of marginalization. In addition, a growing interest in adobe masonry is noticed in two ways: for rescuing the heritage and as a rediscovered environmentally friendly building material. The problems are found of how to carry out the conservation works of the great built heritage with this material, as well as the lack of skilled people at all levels, from designer to masons, because it is a forgotten technique. Hence, some recent investigations about the obtention of adobe mechanical properties and characterization of adobe bricks, including earth blocks, have been performed. This article investigates experimentally destructive and nondestructive tests used for this purpose, especially elastic mechanical properties, considering new sensors, systems and different techniques has led to the inspection of adobe bricks. The results show, compared destructive with nondestructive methods, a good correlation between both techniques. This study contributes towards a better understanding of the elastic mechanical properties of adobe bricks built in Mexico, considered as a developing country.