Ultimate Capacity of Diagrid Systems for Tall Buildings in Nominal Configuration and Damaged State

Abstract

One of the evocative structural design solutions for tall buildings is recently embraced by the diagrid (diagonal grid) IntroductionIt is a common understanding that society requires enhanced structures for the people's needs. Besides safety and functional requirements collectively defined in the so-called Performancebased Design [1], today the attention focuses on the sustainability in the broader and profound sense of the word [2].Sustainability in the urban and built environment is a key issue for the wellbeing of people and society. Sustainable development, defined as the "development that meets the needs of the present without compromising the ability of the future generations to meet their own needs" [3] is nowadays a first concern for public authorities and the private sector. Sustainable design leads to innovation since it demands inventive solutions, and eventually is supported by a cultural shift, evident from national level reviews and surveys [4,5]. Sustainability issues are wide-ranging in the building industry but the main focus is the reduction of energy consumption in construction and use.In construction, steel has developed as a material of choice and offers a wide range of solutions that can make buildings more energy efficient, less costly to operate and more comfortable. Several green solutions, aiming at the minimization of structural steel, have been developed in the last few years. Among those, the diagrid structural system is considered as a promising solution for high-rise steel buildings. Diagrid is a perimeter structural configuration characterized by a narrow grid of diagonal members that are involved both in gravity and in lateral load resistance that has emerged as a new design trend recently for tall-shaped complex structures due to aesthetics and structural performance [6,7].Since diagrid requires less structural steel than a conventional steel frame, it provides for a more sustainable structure.This study focuses on the overall structural performance, the ultimate capacity and the robustness of diagrid tall buildings, using numerical (FE) methods. More precisely, the paper is organized in the following manner. Section 2 provides details on diagrid for high-rise buildings. Section 3 outlines structural robustness approaches for steel buildings. Section 4 introduces the case study steel high-rise building and the performed Finite Element (FE) numerical analyses. Finally, Section 5 provides some

Seismic performance factors for low‐ to mid‐rise steel diagrid structural systems

“…8a-d shows the lateral force versus roof displacement, the pushover curve, obtained by a static nonlinear analysis for the 4-, 8-, 15-, and 30-story models, respectively. Diagrids show large initial lateral stiffness and collapse capacity that is consistent with previous studies [4,32,47]. …”

Diagrid: An innovative, sustainable, and efficient structural system

“…The inclined diagonal members of diagrids are particularly effective for carrying the lateral loads in tall buildings leading to considerable reduction in structural weight and carbon dioxide emission compared to conventional structural systems. For instance, the 182‐m Hearst Tower completed in 2006 shows the potential of diagrid to be a sustainable structural system where the structure is reported to have 20% less steel than “conventional framed structures” . Approximately, 10,000 tons of steel are used for the structure including 90% recycled steel .…”

“…Moreover, it consumes 25% less energy than a conventional office building. Due to this sustainable features, it has obtained a Gold rating from the LEED, the first structure with this distinction in Manhattan, New York …”

“…For instance, the 182-m Hearst Tower completed in 2006 shows the potential of diagrid to be a sustainable structural system where the structure is reported to have 20% less steel than "conventional framed structures". [47] Approximately, 10,000 tons of steel are used for the structure including 90% recycled steel. [70] Moreover, it consumes 25% less energy than a conventional office building.…”

Numerical Modeling and Seismic Analysis of Tall Steel Buildings with Braced Frame Systems

“…Although low-frequency vortex shedding and aerodynamic characterization may have in some cases a significant impact on the response of tall buildings (see e.g. Petrini and Ciampoli [31]), such a comparison, carried out in terms of imposed loads at this stage, revealed the earthquake excitation to be the most demanding of the two conditions. As such, wind and seismic loadings were considered in parallel during the design phase of the two case-study structures, as discussed later on, and then detailed building assessment was performed paying deeper and…”