###### Abstract  
Material optimization was one of the challenges for achieving cost-competitive solutions when concrete was introduced in construction, leading to new structural shapes for both civil works and buildings. As concrete construction became dominant, saving material was given less significance, and the selection of the structural typology was mostly influenced by construction or architectural considerations. Simple and non-time-consuming methods for building thus arose as the dominant criteria for design, and this led to the construction of less efficient structures. Currently, the awareness of the environmental footprint in concrete construction has brought the focus again to the topic of structural efficiency and material optimization. In addition, knowledge of material technology is pushing the use of cements and binders with lower environmental impact. Within this framework, Fiber-Reinforced Concrete (FRC) has been identified as a promising evolution of ordinary concrete construction. In this paper, a discussion is presented on the structural properties required for efficient design, focusing on the toughness and deformation capacity of the material. By means of several examples, the benefits and potential application of limit analysis to design at the Ultimate Limit State with FRC are shown. On this basis, the environmental impact of a tailored mix design and structural typology is investigated for the case of slabs in buildings, showing the significant impact that might be expected (potentially reducing CO\({}_{2}\)-eq emissions to half or even less in slabs when compared to ordinary solutions). the calcination of limestone [11] and the chemical reactions induced. Some strategies to reduce the footprint associated with cement production are thus related to its production (see, for instance, [12]). However, the most efficient way to reduce cement consumption is directly linked to the rational use of this resource by reducing the amount of clinker needed for cement production [13; 14] as well as by designing efficient structures with low consumption of concrete [15]. In this respect, the interest in the use of FRC for concrete construction is currently being actively investigated in terms of the economy of construction and the reduction of carbon footprint [16; 17; 18; 19; 20]. Such works have highlighted the potential of the material to lead to structural designs aligned with the pillars of sustainability [15]. In this regard, it is important to emphasize that the presence of fiber enhances the durability and lifespan of the material due to the reduction in the width of the cracks [21; 22]. As shown by the experience of reinforced concrete construction, exploiting the potential of FRC in view of its application as a more sustainable solution will require not only tailored mixes to reduce the carbon footprint but also suitable structural typologies to minimize material consumption. To that end, the use of fibers can efficiently replace shear reinforcement [23] and eliminate [20] or reduce [24] the necessity of arranging a minimal amount of reinforcement for suitable control of cracking. This fact raises the issue that focusing design efforts only on the material mix or only on the typology is not sufficient and that both shall converge in the adoption of suitable structural shapes. It may be noted that such consideration is not suitably addressed in the literature, and this topic will be investigated in detail in the present manuscript. Within this framework, a relevant aspect related to the design of members cast with FRC is their brittle or ductile structural response, which depends both on the material behavior and on the structural configuration. These aspects, concerning the toughness of the material and the structural configuration, are not always suitably accounted for in design but shall be recalled as being instrumental for the design of a structure. In this paper, the structural behavior of FRC is investigated and its material and structural responses in a coupled manner are considered.