Towards a unified approach for the analysis of failure modes in FRP-retrofitted concrete beams

The application of the external reinforcement makes rather complex the scenario of the possible failure modes in reinforced concrete beams retrofitted with FRP. The far more commonly observed failure modes are: (i) edge debonding of the FRP sheet, (ii) intermediate crack induced debonding and (iii) beam failure due to diagonal (shear) crack propagation. In the present study we revisited the competition between all the possible failure modes that can occur in this structural element. To this aim, different analytical models based on linear and non-linear fracture mechanics are developed and harmonized. As a result, useful failure maps are analytically determined, giving, for each failure mode, the critical load of activation as a function of the main parameters governing the problem, i.e. the mechanical properties of the constituent materials, the amount of reinforcement and its bonding length, as well as the size and slenderness of the structural element. The studies presented in this paper are mainly intended to establish guidelines for the future development of these concepts towards a unified mathematical approach. Indeed, once the validity of this unified approach is confirmed, also by comparison with further experimental data, it will be possible to remove some of the simplifying assumptions we used in this analysis to reach a more comprehensive analytical formulation

Standard methods for toxicology research in Apis mellifera

Modern agriculture often involves the use of pesticides to protect crops. These substances are harmful to target organisms (pests and pathogens). Nevertheless, they can also damage non-target animals, such as pollinators and entomophagous arthropods. It is obvious that the undesirable side effects of pesticides on the environment should be reduced to a minimum. Western honey bees (Apis mellifera) are very important organisms from an agricultural perspective and are vulnerable to pesticide-induced impacts. They contribute actively to the pollination of cultivated crops and wild vegetation, making food production possible. Of course, since Apis mellifera occupies the same ecological niche as many other species of pollinators, the loss of honey bees caused by environmental pollutants suggests that other insects may experience a similar outcome. Because pesticides can harm honey bees and other pollinators, it is important to register pesticides that are as selective as possible. In this manuscript, we describe a selection of methods used for studying pesticide toxicity/selectiveness towards Apis mellifera. These methods may be used in risk assessment schemes and in scientific research aimed to explain acute and chronic effects of any target compound on Apis mellifera