Increasing concerns regarding litigation and terrorism provide a strong dual motivation to decrease high explosives usage in the construction industry. This paper provides parameter considerations and initial guidelines for the application of expansive fracture agents, typically used for concrete and soft rock removal. This approach may be especially appropriate near environmentally and historically sensitive sites. Thirty-three unreinforced blocks (approximately a cubic metre each) of varying strengths, composed of sand, cement, and fly ash, were tested under various temperature environments, with differing expansive agents, confinement levels and post-cracking treatments. Cracking characteristics such as crack initiation and crack expansion were analysed. Although the performance of expansive cement was dependent on a highly complex set of variable interactions, higher ambient temperatures, higher agent mixture temperatures and chemical configuration designed for colder temperatures decreased the time to first crack and hastened the extent of cracking. Conversely, higher strength material required more time to first crack, as well as an extended time to achieve a 25 . 4 mm wide crack. Manual interference with the normal material volume expansion slowed the cracking process but did not truncate it, while the manufacturer's recommendation to introduce water post-cracking actually reduced and slowed the extent of cracking.

This paper describes a collaborative project between the US, Ireland, and Northern Ireland (UK) to investigate advanced manufacturing cutting techniques for the creation of a new class of intermeshed steel connections that rely on neither welding nor bolting. To date, advanced manufacturing equipment has only been used to accelerate traditional processes for cutting sheet metal or other conventional fabrication activities. Such approaches have not capitalized on the equipment's full potential. This project lays the groundwork to transform the steel building construction industry by investigating the underlying science and engineering precepts for intermeshed connections created from precise, volumetric cutting. The proposed system enhances the integration between design, fabrication, installation and maintenance through building information modeling platforms to implement advanced connections. Fully automated, precise, volumetric cutting of open steel sections introduces intellectual challenges regarding the load-transfer mechanisms and failure modes for intermeshed connections. The research activity addresses knowledge gaps concerning the load resistance and design of steel systems with intermeshed connections. Physical tests, finite element simulation and multi-scale modeling are being used to investigate the mechanics of intermeshed connections including stress and strain concentrations, fracture potential and failure modes, and to optimize connection geometry.

Soundless chemical demotion agents (SCDAs) are percussion-free alternatives to blasting for rock, concrete, and masonry. They hold great potential for selective demolition of and around historic masonry. Although known to be temperature sensitive, to date their performance has not been quantified in ambient environments below 20˚C.

In recent years, advanced manufacturing techniques, such as high-definition plasma, water jet, and laser cutting, have opened up an opportunity to create a new class of steel connections that rely on intermeshed (i.e. interlocked) components. The main advantage of this type of connection is that they do not require either welding or bolting, which allows faster construction. Although the interest in intermeshed connections has increased in recent years, the mechanical behavior of these connections has not been fully understood. This paper presents a numerical study on the ultimate load capacity failure modes of intermeshed connections under mixed-mode loading. The experimental behavior of the connection components is also investigated through a series of tests. The study considers a recently developed intermeshed connection for beams and columns. The numerical simulations were performed by using a commercially available 3D finite element software package. By considering different types of mixed mode loading, interaction diagrams of axial, shear, and moment capacities of the intermeshed connection were obtained. The results 2 indicated that there exists an intricate interaction among axial, shear, and moment capacities, which arises from the intermeshed configuration of the flanges and web. For each interaction diagram, the corresponding failure mechanism was analyzed. The simulated interaction between axial, shear, and moment capacities were further compared with the provision of the current design codes. While the intermeshed connection studied here showed promise for gravity loading, further study is needed to ensure alignment of the flanges so as to avoid axial and/or flexural failures.

Digital manufacturing has transformed many industries but has had only a limited impact in the construction sector. To capitalize on advanced manufacturing techniques, this paper introduces a radically new connection approach for gravity structural steel frames. The proposed intermeshed steel connection (ISC) exploits robotic abilities to cut structural steel member ends precisely to accelerate deployment and offer better disassembly options over existing approaches. Forces are transferred through common bearing surfaces at multiple contact points, and connections can be secured by small locking pieces. This paper introduces the geometry, manufacturing, and initial analysis and test results of the connection. The paper demonstrates the ability of the connection to (1) be manufactured within current industrial tolerances, (2) be erected and disassembled, and (3) perform at expected design levels.