Performance-based specifications (PBS) may increase concrete quality and sustainability by facilitating innovations in material selection and proportioning. This is particularly relevant now with increased interest in a broader set of minimally processed minerals for use as supplementary cementitious materials (SCMs) or fillers; these are often industrial and agricultural byproducts and with limited performance history in concrete. This study compares traditional largely prescriptive concrete design, following practices currently allowed by the Georgia Department of Transportation, with three new concrete designs which do not comply with current specifications but offer increased sustainability. Three metrics are assessed for each mixture: the associated cradle-to-gate CO₂ emissions, a metric that incorporates the environmental burden of concrete, compressive strength at 28 days, and surface resistivity measurements taken weekly from 28 to 56 days. A framework is proposed to statistically analyze compressive strength data to pre-qualify mix designs, which can be broadly applied to reduce time-consuming iterative testing and to help meet sustainable development goals. The aim is to foster innovation in material use and mixture design towards an increased durability and performance, while reducing environmental impact and minimizing risk.

Fibre reinforced concrete (FRC) is becoming widely utilized in segmental linings due to the improved mechanical performance, robustness and durability of the segments. Further, significant cost savings can be achieved in segment production and by reduced repair rates during temporary loading conditions. The replacement of traditional rebar cages with fibres further allows changing a crack control governed design to a purely structural design with more freedom in detailing. Macro synthetic fibres (MSF) are non-corrosive and thus ideal for segmental linings in critical environments. Although fibre reinforcement for segments is relatively new, recent publications such as the ITAtech “Guidance for precast FRC segments – Volume 1: Design aspects” or the British PAS 8810 “Tunnel design – Design of concrete segmental tunnel linings – Code of practice” have now given more credibility to this reinforcement type and the basis for design. This paper presents and discusses the design methodology for precast tunnel segments and in particular the tasks associated with the use of MSF reinforcement. Temporary loadings as well as long term load behaviour will be addressed. A case history from the Santoña–Laredo General Interceptor Collector, currently under construction in northern Spain, will illustrate the specific benefits of MSF reinforcement for segmental linings.

With over 80 years of history, it is only in the last 20 years that the use of fiber reinforced polymer (FRP) materials has become feasible for bridge applications in part due to the ever increasing requirement to make structures last longer, with the current American Association of State Highway Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications requiring that structures be designed for a 75 year design life; but also in the development of cost effective production techniques, and the introduction of FRP materials, which bring the cost and strength of FRP materials closer to traditional steel reinforcement. Published documents provide comprehensive recommendations on design methodology, predictive equations, and recommendations for strength and service limits states. In this paper, the background of FRP-prestressed concrete bridges is discussed and trial bridges are designed. Research needs to advance the state of the art are identified and delineated.

Performance based seismic design (PBSD) has been widely used for tall buildings as a code alternative design method for concrete shear wall structures. However, most PBSD studies are done for buildings taller than 240’ (73 m). Very few studies have been done for buildings shorter than 240’ (73 m) because PBSD is not required for buildings under 240’ (73 m). It is unclear if and how the shear demand increases observed in typical PBSD analysis should be applied to buildings shorter than 240’ (73 m). This study includes two buildings in the Seattle area that are designed per current codes. The study compares the shear demands predicted by the elastic analysis method with the demands predicated by the nonlinear time history analysis used in PBSD method. The intent of this study is to examine the merits of the new Seattle requirement using a factor to amplify the shear demand for buildings designed at code level and for the building height in the range of 160’ (48.8 m) to 240’ (73 m). It also explores the proper factor to be used in ACI 318 to determine the shear wall capacity.

The new Terminal 2 at the Tocumen International Airport in Panama, currently essentially completed, will increase the airport’s capacity to 25 million passengers per year. It has a doubly curved steel roof supported on reinforced concrete columns. The gravity force-resisting systems in the superstructure include long span precast and prestressed double tee decks, topped with cast-in-place concrete diaphragms and supported on a combination of unbonded post-tensioned girders and special reinforced concrete moment frame beams. The seismic force-resisting system includes special reinforced concrete moment frames and perimeter columns, special reinforced concrete shear walls and diaphragms, all detailed in accordance with ACI 318. Located in a region of moderately high seismic hazard, the building is classified as an essential facility and requires a non-conventional seismic design approach to maintain operational continuity and to protect life. Adopting the performance-based seismic design methodology and the capacity design principle, the structural engineering team designed an innovative reinforcement detail for developing ductile hinges at the top of the reinforced concrete columns to protect the structural steel roof which is designed to remain essentially elastic under MCE shaking. The structural engineering team’s design has been reviewed by internationally recognized experts and three independent peer review teams.