Concept and cable-tensioning optimization of post-tensioned shells made of structural glass

Shells made of structural glass are charming objects from both the aesthetics and the engineering point of view. However, they pose two signicant challenges: the rst one is to assure adequate safety and redundancy concerning possible global collapse; the second one is to guarantee the economy for replacing collapsed components. To address both requirements, this research explores a novel concept where triangular panels of structural glass are both post-tensioned and reinforced to create 3D free-form systems. Hence, the ligree steel truss, made of edges reinforcements, is sized in performance-based perspective to bear at least the weight of all panels in the occurrence of simultaneous cracks (worst-case scenario). The panels are post-tensioned using a set of edge-aligned cables that add benecial compressive stress on the surface. The cable placement and pre-loads are optimized to minimize the tensile stress acting on the shell and match the manufacturing constraints. These shells optimize material usage by providing not only a transparent and fascinating building separation but also load-bearing capabilities. Visual and structural lightness are improved to grid shell competitors

Textile Roofs 2019: Report

Postprint (published version

Case study of assembly defects in manufactured products

Design for Quality Manufacturability (DFQM) is a design tool that empowers engineers to create designs that are easily and effectively transformed into manufactured products. The goal of this methodology is to make designers aware of design characteristics that may lead to product defects during the assembly process. Acknowledging the possibility of these defects will enable the designer to institute design modifications early in the design phase. The benefits realized in this approach are a reduction in the number of defects in the finished product, reduced product cycle times, a reduction in monitoring costs and a reduction in time-to-market. This thesis supports the application of the DFQM methodology as a means of maintaining a competitive advantage within industry. The value of utilizing this approach is proven by the submitted case studies of quality defects. An automobile emergency brake, portable overhead projector, car door handle, hand soap dispenser, floppy disk drive and hand held hair dryer were analyzed using the DFQM classes of Manufacturing Quality Defects. Through this analysis, Influencing Factors and Factor Variables of the each design were isolated and suggestions for modifications were presented to eliminate these quality defects

A Review of Fibre Reinforced Polymer Bridges

Fibre reinforced polymer composites (FRP) offer various benefits for bridge construction. Light-weight, durability, design flexibility and fast erection in inaccessible areas are their unique selling points for bridge engineering. FRP are used in four bridge applications: (1) FRP rebars/tendons in concrete; (2) repair and strengthening of existing bridges; (3) new hybrid-FRP bridges with con-ventional materials and (4) all-FRP composite new bridges made entirely of FRP materials. This paper reviews FRP bridges, including all-FRP and hybrid-FRP bridges. FRP bridges’ history, ma-terials, processes and bridge components – deck, girder, truss, moulded parts and cables/rebars are considered. This paper does not discuss use of FRP as an architectural element and a strengthening system. While lack of design codes, material specifications and recycling are the major challenges, the high cost of FRPs still remains the most critical barrier to the progress of FRPs in bridges

Design of concrete walkway bridge with fiber and prestressed reinforcement

The advances made in the field of prestressed concrete have widened the freedom in building structures. This allows achieving high loading capacity with the adaption of longer spans and smaller cross-section dimensions. Post-tensioning technique of prestressing is the most adopted method by the industry due to many advantages. Fiber reinforcement improves the material properties of the concrete through increased general tenacity, reduction of crack widths, and a well-documented increase of shear capacity. (Kanstad, et al., 2020) However, fiber-reinforced concrete is rarely used in load-bearing structures due to lack of experience and guidelines. Its use may increase as the Norwegian Concrete Association's recently published publication no. 38 ‘’Fiber-reinforced concrete in load-bearing structures’’ (NB38) provides guidance in the use of fiber concrete. Post tensioning reinforcement combined with fiber reinforced high strength concrete is the foundation on which a walkway bridge for this thesis is designed as a study case. It is designed after NB38 combined with the newest draft of EN1992-1-1 with Annex L for fiber reinforcement. The draft of the standard is used for experimental reasons and with interest in looking at future design principles. The thesis examines the potential of designing structural elements with small cross-sections that leads to aesthetically pleasing structures with opportunity to decrease material use and the use of extra reinforcement. The standards have a required minimum amount of reinforcement for constructions where a collapse can lead to loss of human life or cause large social costs. It is concluded that over half the volume of concrete used for the bridge elements does not need more reinforcement than the minimum, and thus a great deal of reinforcement steel is saved. This leads to significant economic and environmental benefits and points to the advantages of fiber reinforced and prestressed concrete. The structural design of the bridge is based on similar bridges such as (Lopez, et al., 2015) and (di Prisco, et al., 2022) that both are interesting projects with the implementation of a post-tensioned fiber reinforced concrete. Bridges like these are implementing ultra-high strength concrete, with strengths up to =150 . However, with the prerequisites of the thesis to be NB38 in combination with the Eurocode draft, the concrete strength has been reduced to an appropriate value of =100 to be eligible with formulas from this literature

Self-engineering – Technological Challenges

Engineered products are becoming more complex and need longer lifetime availability; there is a need for new approaches in maintaining, repairing and overhaul (MRO). This paper presents the concept of self-engineering; the aim is to preserve the functions of a product or system and extend its lifetime and automate MRO processes. New developments in self-healing materials, self-reconfiguring electronics and robotics, which are already or could be self-engineering systems, are reviewed. Biological healing and repair mechanisms are discussed as a potential source of inspiration for new self-engineering systems. Examples of biological self-engineering are presented. Key technological challenges and research questions which need to be addressed in future self-engineering research are discussed throughout

Standard Specifications for Road and Bridge Construction, January 1, 2015

https://digitalcommons.memphis.edu/govpubs-tn-dept-transportation-standard-specifications/1006/thumbnail.jp