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.

This paper investigates experimentally the effectiveness of a cost-effective strengthening technique using steel meshes at improving the seismic behaviour of adobe dwellings typical of developing countries. To achieve this, two 1 : 2 scaled-down adobe dwellings were tested on a shaking table using increasing levels of shaking intensity. The first model was tested in an as-built condition, whereas the second one was strengthened with a hexagonal chicken-wire mesh rendered with cement mortar. The main parameters investigated include the vibration period, accelerations, displacements, damping, stiffness and base shear. The results show that, compared to the as-built model, the reinforced model sustained twice the accelerations and experienced 10 times less drift, while only increasing by approximately 20% the material and labour costs. It is also shown that the proposed strengthening strategy was very effective at reducing structural damage in adobe dwellings. This study contributes towards a better understanding of the seismic response of adobe structures, as well as towards developing cost-effective strengthening techniques for structures in developing countries.

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 development and construction of highway infrastructure are essential in developing countries, whereas its layout and construction sometimes interact with the coastal environment. One problem to attend to is that the outline and geometry designs impact as little as possible on the hydrodynamic circulation of coastal bodies in order to alter the associated ecosystem as little as possible. The study area is located in the north of Colombia, and is made up of a continental coastal zone (Mallorquín Lagoon) and a marine zone (Caribbean Sea), in which a highway is projected that provides communication between two locations. This study presents the application of a numerical model previously developed and modified by the Berkhoff equation, which is developed in a finite difference scheme and has been validated and applied in different works in coastal and fluvial shallow water areas. The application of the model was carried out in a hydrodynamic circulation research project for a one-way highway through a coastal lagoon, where the knowledge of the magnitude of the incident wave height in the structure of the road body is necessary for the design, protection elements, and road geometry. Two numerical simulation scenarios were carried out, specifying normal conditions and extraordinary wave conditions in the month of November with a simulation time of 15 days, obtaining the velocity field associated with coastal currents, waves, and wave modification phenomena, such as refraction, diffraction, and reflection, which provide the height of the incident wave on the highway and the recirculation patterns in the coastal lagoon to identify alterations in the ecosystem. The results of the wave height in each scenario and the velocity field provide values to be used in the design, type of armor, and dimensions of the protection works required for the proper functioning of the road structure.

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.