International Concrete Abstracts Portal

Lightweight and high-performance materials have become necessary for infrastructure with advanced construction and performance requirements. One of the major challenges with structures made of these materials is their performance under natural and man-made hazards, such as wind, fire, and blast. Therefore, in this study, the performance of ultra-high-performance concrete (UHPC) and UHPC coated with foamed concrete (UHPC-Foamed) and polyurea (UHPC-Polyurea) is investigated under blast load. A finite element model is developed to assess the behavior of UHPC and coated UHPC panels under far-field and near-field blast scenarios. The constitutive behaviors of UHPC and foamed concrete are considered using the concrete damage plasticity model with respective parameters. The polyurea is modeled as a hyperelastic material with the Mooney-Rivlin model. Moreover, the effectiveness of the additional coatings, i.e., foamed concrete and polyurea, on the blast resistance of each panel is presented. The finding of the study shows that both foamed concrete and polyurea enhance the blast resistance of the UHPC concrete panels. Moreover, a comparison between the blast resistance of UHPC-Foamed and UHPC-Polyurea is conducted under far-field and near-field blast scenarios. Also, the effectiveness of foamed concrete and polyurea coatings with different thicknesses to UHPC panels is assessed under both blast scenarios.

Although radiation is used for many useful purposes today, it has properties that can cause serious harm to human health. Especially, the harmful effects of radiation come from radioactive sources used for diagnosis and treatment in hospitals. Armoring the environment that is used and preventing its effect from being transferred to the external environment is one of the most frequently used methods. For this purpose, lead plates (0.1-3 mm) and concrete (6-26 cm) are used in hospitals. The new building material to be produced is healthy compared to lead since it will have a thin section compared to concrete, and it will have the characteristics of lightness and workability. Precautions to be taken in concrete against radiation are available in the literature, but the concretes in the proposed solutions are both heavy, prone to cracking, and have low fire resistance. In this study different fine minerals are optimized to minimize pores and X-Ray, gamma, and neutron shielding effectiveness were measured. Different thicknesses 1-5 cm were molded after the preparation of glass fiber-reinforced concrete (GRC) to get an equivalent value of 2 mm lead.

Fireproofing deterioration is widespread in industrial facilities throughout the country. Spalling concrete has potential to damage equipment and harm personnel. Replacing concrete fireproofing like-in-kind, without consideration for proper anchorage or material durability, does not eliminate the hazard as spalls may potentially occur again over time. However, when properly designed and installed, concrete is a durable option for replacing deficient fireproofing in aggressive environments typically present in industrial processing units. This paper presents the results of a case study on a structure in a Midwest industrial complex. Extensive concrete fireproofing repairs were performed on the structure 12 years ago. Design requirements included normal weight concrete with polypropylene fibers which enhance durability by improving cracking resistance. During a fire, the fibers melt forming relief channels for moisture to escape, thus eliminating explosive spalling. Installation methods included welded wire reinforcement (WWR) with positive anchorage to structural steel. WWR was attached to post-installed adhesive anchors between column flanges where existing fireproofing was sound and difficult to remove. After 12 years in service, repairs exhibit no significant defects. This level of durability is attributed to the design and installation methods utilized. Concrete fireproofing is a durable option for fire protection, provided structures are designed to support its weight, its mixture design is properly proportioned, and it is adequately anchored and reinforced.

This paper presents the development of a data-driven deep neural network (DNN) for evaluating the fire resistance time of fiber-reinforced polymer (FRP) strengthened concrete beams. The model was trained for a scaled and unscaled dataset. For this, a comprehensive dataset of FRP-strengthened concrete beams with different geometry, insulation configuration, applied loading, and material characteristics was compiled. The DNN structure was selected after an extensive hyperparameter tuning in conjunction with ten-fold cross-validation scheme. The effect of different input parameters on the fire resistance prediction was analyzed. The DNN model developed using scaled data provides a reasonably accurate estimate, of the fire resistance of FRP-strengthened concrete beams with an R2 value of almost 92%. The developed model is further utilized to evaluate the impact of different parameters on fire resistance prediction for FRP-strengthened concrete beams. Results from the analysis indicate the thermal properties of insulation play an important role in determining the fire resistance of FRP-strengthened concrete beams.

A new partially prefabricated elevated slab has been recently introduced in two different industrial buildings, to propose a viable alternative to the classical double tee deck with the addition of an in-situ RC topping. The solution is characterized by an adjustable spacing in the orthogonal direction, 40 mm thick FRC plates used as predalles and a cast-in-place FRC finishing, designed according to a continuous slab resting on the simply-supported beams. The proposed deck is a structural solution that tries to fit different issues like construction speed, transport and cost reduction, structural optimization, high fire resistance (R120) and quality performance. All elements are made of SFRC, characterized by different mix designs. This paper presents a design investigation on this kind of floor element, aimed at optimizing the global structural solution by minimizing the whole floor weight. Longitudinal and transverse bending, as well as vibration limit state, were considered in the design. The optimization strategy will be here presented, through the discussion of the parameters considered in the design, the variables taken into account and the constraints adopted within the procedure. A Model Code 2010 design approach was followed.