refereed Journal Articles

Title

Lattice discrete particle modeling of the cycling behavior of strain-hardening cementitious composites with and without fiber reinforced polymer grid reinforcement

Journal | Volume

Composite Structures; 2023

Authors

Z Zhu, M Troemner, W Wang, G Cusatis, Y Zhou

abstract

Strain-hardening cementitious composites (SHCC) has become increasingly prevalent in structural design. Compared to ordinary concrete, SHCC exhibits ultra-high tensile ductility, significant strain-hardening behavior, very fine multi-point cracking, high energy dissipation, and good durability. One robust model for simulating reinforced concrete behavior is the so-called Lattice Discrete Particle Model (LDPM), and specifically LDPM-F which includes the effect of fiber reinforcement. The present cycling constitutive law implemented in LDPM and the cycling fiber-bridging law in LDPM-F though cannot accurately capture the residual tensile plastic strain, loading-unloading path, and energy dissipation of SHCC during cyclic tension. To solve these concerns, the cycling tension-compression constitutive law and the nonlinear cycling fiber-bridging law were reformulated. Further, the new model was used to simulate the …

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Title

Lattice discrete particle modeling of concrete under cyclic tension–compression with multi-axial confinement

Journal | Volume

Construction and Building Materials; 2022

Authors

Z Zhu, M Pathirage, W Wang, M Troemner, G Cusatis

abstract

Accurate modeling of concrete mechanical behavior under cyclic loading with different levels of confinement is crucial in design and analysis of structures subjected to seismic events. One robust model for simulating concrete behavior is the Lattice Discrete Particle Model (LDPM), a discrete model formulated at the scale of aggregate and composed of polyhedral cells connected through a lattice of nonlinear fracturing struts. To improve the performance of LDPM for the prediction of mechanical behavior under different cyclic loading schemes and multi-axial confinement, a comprehensive cycling constitutive model, a modified volumetric–deviatoric compression law, and a modified frictional behavior under compression are established in this study. An effective strain and a corresponding effective stress at the mesoscale are formulated and used to determine the stress–strain relationship under monotonic loading. In …

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Title

A 3D-Printing Centered Approach to Mars Habitat Architecture and Fabrication

Journal | Volume

ASCE Journal of Aerospace Eng.; 2022, Vol. 35, Issue 1

Authors

Matthew Troemner, E. Ramyar, J. Meehan, B. Johnson, N. Goudarzi, and Gianluca Cusatis

METRICS

abstract

It is seemingly inevitable that one day humans will land on the surface of Mars. Between the Apollo lunar missions, International Space Station, and Martian rovers and landers, much of the technology required to transport astronauts to Mars already exists; however, how those humans will live and sustain themselves on the Martian surface is yet to be clearly defined. Since at least the 1980s, researchers have envisioned what a Martian habitat may look like, and what its inhabitants will require. Spanning from domed cities to lava tube shelters, the bases of conceived designs are vast. Through NASA's 3D-Printed Habitat Challenge, the American space agency has put large scale 3D-printing technology at the forefront of this endeavor. This paper presents the rationale for the Martian habitat designed by Northwestern University, in partnership with Skidmore, Owings and Merrill, for submission in NASA's 3D-Printing Habitat Challenge Virtual Design Levels. The habitat includes housing for four astronauts, room for one year of supplies, 93 m2 living space, and various prescribed volumes of equipment, to name a few. Defined by a unique outer-parabolic and inner-hemispherical shell, the proposed habitat takes a 3D-printing centered approach for its architecture and fabrication.

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Title

Martian Material Sourcing Challenges Propel Earth Construction Opportunities

Journal | Volume

Matter; 2019, Vol. 1, Issue 3 pp. 547-549

Authors

Troemner, Matthew; Cusatis, Gianluca

metrics

abstract

Few places in our solar system have captured the collective imagination of society quite like Mars. Thoughts conjured include imagery of glass domes encapsulating skyscrapers and vast fields of solar arrays extending into the expanse—a truly futuristic landscape. However, when humans first arrive, the sight will be quite the opposite. Aside from a few rovers, the surface is desolate of earthly equipment or engineered-structures, anything astronauts will need must be transported or created on site. Mars offers substantial quantities of sand (or regolith) for construction, though it lacks in other typical building materials. Fortunately, an active geochemical sulfur cycle exists, providing an abundance of sulfur compounds on and near the surface. While not typical in modern industry, sulfur concrete was explored on Earth in limited applications. A study of Martian regolith sulfur concrete (Marscrete) has confirmed its use as a structural material, and even indicated significantly greater strengths than its traditional Earth-based counterpart. Harnessing the ability to efficiently translate disruptive 3D-printing technology to the world of construction remains an ongoing challenge. Martian fabrication will almost certainly require such automation, though—and thus, it must be addressed. While a feat on its own, confronting Martian material sourcing challenges may in fact propel opportunities for 3D-printing in Earth construction.

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Title

Notes on the AISC 360-16 Provisions for Slender Compression Elements in Compression Members

Journal

AISC Engineering Journal

Authors

Geschwindner, Louis F.; Troemner, Matthew

VOLUME

2016, Vol. 53, No. 3 pp. 137-146

abstract

Compression member strength is controlled by the limit states of flexural buckling, torsional buckling, and flexural-torsional buckling, as applicable. These compression members may buckle globally or locally, depending on the overall column slenderness and the local plate element slenderness for the plates that make up the shape. If any of the plate elements will buckle at a stress lower than that which would cause the column to buckle globally, the local buckling of the plate will control the overall column strength. When this occurs, the column is said to be composed of slender elements.

This paper will briefly discuss past specification provisions for slender element compression members and introduce the new provisions in the 2016 AISC Specification. It will present a simplification that reduces the number of constants that must be used and will present the specification requirements in an alternate format. Because the 2016 requirements result in different strengths than the 2010 requirements, figures are provided to illustrate the overall impact of these changes on column strength.

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refereed Conference Articles

Title

Design and Analysis of 3D-Printable Thin-Shell Dome Structures for Extraterrestrial Habitation

conference

ASCE Earth & Space Conference

Authors

Troemner, Matthew; Ramyar, E.; Johnson, B.; Cusatis, G.

date

2021, April

abstract

Extreme environmental conditions, unusual loadings and, most importantly, the availability of novel construction techniques will likely dictate the form of any extraterrestrial habitat built on Mars. While a habitat could be constructed by astronauts, it is highly preferred for such a structure to already exist when the first humans land on the Martian surface. Thus, automated structure fabrication, equipped with 3D-printing technologies that use in situ resources is an intriguing approach to consider. This paper presents an overview of the design and analysis of a dome-shaped Martian habitat that was designed at Northwestern University in collaboration with Skidmore, Owings & Merrill (SOM) as part of NASA’s 3D-Printed Habitat Challenge. The structure has a novel composite hemispheric-parabolic dome that is optimized to sustain self-weight and environmental loads, and to be 3D-printed on an inflatable pressure vessel with Marscrete, a Martian concrete manufactured primarily with local Martian regolith and sulfur. This study examines the structural performance of such a habitat under expected Martian loading conditions, including wind, regolith deposition from storms, and gravity. Furthermore, the habitat performance is assessed under meteorite impact of varying masses and velocities. Finally, a construction scheme, potential internal layout, and functional usability of spaces is also envisioned for a four people unit.

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Title

Marscrete, a Martian Concrete for Additive Construction Applications Utilizing In Situ Resources

conference

ASCE Earth & Space Conference

Authors

Troemner, Matthew; Ramyar, E.; Marrero, R.; Mendu, K.; Cusatis, G.

date

2021, April

Astronauts in the Apollo moon landings were provided a prefabricated habitation structure for the short duration on the lunar surface. While the Apollo Lunar Module was designed to house astronauts for only 75 hours, a Martian habitat will require a much greater lifespan. For humans to thrive on Mars for any extended period, semi-permanent structures will have to be erected. Such a large and robust habitat would be impractical to transport prefabricated, thus utilization of local geo-environmental resources is desired. This study presents recent research performed at Northwestern University towards the formulation and characterization of a Martian infrastructure material, called Marscrete. Marscrete is composed, in its simplest version, by sulfur and Martian regolith with a 50-50 mass ratio. Sulfur is plentiful in compounds on and below the surface of Mars, and regolith is a ubiquitous material. Marscrete is the Martian version of traditional sulfur concrete which is manufactured by melting sulfur and mixing it with sand with approximately a 25-75 mass ratio. Results on compression strength tests, splitting tensile strength, and fracture tests show that Marscrete has significantly better mechanical properties than traditional sulfur concrete and even standard Portland cement concrete. While a generically suitable construction material, Marscrete, when modified with mission-recycled polyethylene fibers, also demonstrates high capabilities for 3D-printing applications – a likely automated construction technique of Martian structures. This paper will discuss the rheological behavior of fresh printable Marscrete, structural performance of the hardened composite, and pose an apparatus to produce 3D-printed Marscrete.

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Magazine Articles

Title

Five Steps to 3D-Printing a Home on Mars

Magazine

The Possible

Author

Troemner, Matthew

abstract

Our team at Northwestern University is taking part in NASA’s 3D-Printed Habitat Challenge, exploring additive construction technology to create housing for deep-space exploration, including its 2033 mission to Mars. If you’re going to Mars for any extended period of time, it doesn’t make sense to send all of your resources from Earth — the transport costs would be enormous. So you have to produce habitats and structures using what’s already there on the planet’s surface, through 3D-printing or another manufacturing process.

We’re using a concrete based on sulfur. Sulfur is readily available on Mars, and it doesn’t need water. There is frozen water within the planet’s surface, but you’ll need that to live on, so we didn’t want to utilize such a precious resource as a building material. For testing, we’re mixing it 50/50 with a basalt-based simulant from the Mojave desert…

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Title

Specwise: What's New in the Spec?

Magazine

Modern Steel Construction

Authors

Baer, Sam; Troemner, Matthew

abstract

AISC is set to release the 2016 edition of the Specification for Structural Steel Buildings (ANSI/AISC 360-16) in the near future.

Changes from the 2010 edition reflect the Committee on Specifications’ desire to implement only essential changes that reflect new research, provide for more efficient designs or broaden its scope. Many of these changes were technical in nature, though edits were also made that focused on improving usability, transparency and editorial content.

The following is a brief overview of the most significant changes, some of which have the potential to substantially affect design procedures. A complete list of differences between the 2010 and 2016 AISC Specification will soon be available as a free download at www.aisc.org/manualresources.

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codes/specifications

Title

Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications

standard

ANSI/AISC 358-16 American National Standard

approval board

Connection Prequalification Review Panel

Contributors

Arber, L., Carter, C., Duncan, C., Malley, J., Miller, D., Pryor, S., Saunders, C., Troemner, M.

Abstract

ANSI/AISC 358-16, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications, was developed using a consensus process in concert with the Specification for Structural Steel Buildings (ANSI/AISC 360-16) and Seismic Provisions for Structural Steel Buildings (ANSI/AISC 341-16). ANSI/AISC 358-16 is incorporated by reference into the Seismic Provisions.

This Standard specifies design, detailing, fabrication and quality criteria for connections that are prequalified in accordance with the AISC Seismic Provisions for Structural Steel Buildings (herein referred to as the AISC Seismic Provisions) for use with special moment frames (SMF) and intermediate moment frames (IMF). The connections contained in this Standard are prequalified to meet the requirements in the AISC Seismic Provisions only when designed and constructed in accordance with the requirements of this Standard. Nothing in this Standard shall preclude the use of connection types contained herein outside the indicated limitations, nor the use of other connection types, when satisfactory evidence of qualification in accordance with the AISC Seismic Provisions is presented to the authority having jurisdiction.

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