Treesearch

Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites)1–8. Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction9. However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treat...

We present a continuum-based structural model to study the mechanical behavior of cel- lulose nanocrystals (CNCs), and analyze the effect of bonded and non-bonded interactions on the mechanical properties under various loading conditions. In particular, this model assumes the uncoupling between the bonded and non-bonded interactions and their be- havior is obtained from atomistic simulations. Our results indicates that the major contri- bution to the tensile and bending stiffness is mainly due to the cellulose chain stiffness, and the shear behavior is mainly governed by Van der Waals...

Cellulose nanofibrils (CNF) were sulfonated and the dispersion quality was compared to unfunctionalized and 2,2,6,6-tetramethylpiperdine-1-oxyl radical (TEMPO) post-oxidation treatment of existing CNF (mechanically fibrillated pulp). A post-sulfonation treatment on existing CNF in chlorosulfonic acid and dimethylformamide (DMF) resulted in sulfonated CNF that retained a fibril-like morphology. There was a small decrease in the cellulose crystallinity index for the sulfonated CNF, but this was much lower than the reported regioselective oxidative bisulfite pretreatment method used to make...

Nature uses a wide variety of chemicals for providing adhesion internally (e.g., cell to cell) and externally (e.g., mussels to ships and piers). This adhesive bonding is chemically and mechanically complex, involving a variety of proteins, carbohydrates, and other compounds.Consequently,the effect of protein structures on adhesive properties is only partially understood and creates an inherent difficulty in understanding protein structure-property relationships. This complexity has limited researchers in the past to mainly depend on empirical studies for insight, with a few exceptions....

A tornado safe room is a shelter designed to provide protection during a tornado and is specifically engineered to resist the high wind pressures and debris impact generated by these high wind events. The required performance criteria of these shelters has been established and is found in the International Code Council Standard for the Design and Construction of Storm Shelters. A tornado safe room has been developed from commodity wood products and is described in “A Residential Tornado Safe Room from Commodity Wood Products: Design and Development”. In designing this structure, several...

In the United States, tornadoes cause significant damage and result in many injuries and deaths. Although the development and use of tornado safe rooms have helped decrease the human toll associated with these events, the cost of these structures is often too high for many that could benefit from their use. The development of a nonproprietary residential tornado safe room constructed from commodity wood building products, buildable by a local contractor or do-it-yourselfer, and adaptable to existing homes, could lower the cost of these structures and result in more widespread use. This...

The purpose of this study was to develop test data needed to characterize lateral load performance of structural insulated panel (SIP) walls with full bearing (restrained). The research program involved structural testing of 29 full-size SIP walls (8 ft tall by 8 ft long) of various configurations that bracket a range of SIP wall configurations commonly used in the field. Results indicated that the cyclic performance parameters for all walls tested in this study met the over-strength and ductility capacities of ICC-ES AC04, although some walls had drift capacities slightly lower than the...

An extended plate and beam (EP&B) design was developed at Home Innovation Research Labs (Upper Marlboro, Maryland) in an effort to provide traditional light-frame wall construction details that are compatible with continuous insulating sheathing. This would encourage wide-spread adoption of high-R walls and promote greater energy efficiency in new houses. The new wall design provides significant increases in insulation and ensures moisture management while relying on common methods and materials for framing, insulation, and siding attachment. It incorporates the use of foam sheathing...

The bright spot in September was new single-family sales, but housing starts appear to have stalled on a monthly basis. Regionally, data were mixed across all sectors. New construction spending’s contribution to U.S. gross domestic product decreased on a quarterly basis.

The bright spot in September was new single-family sales, but housing starts appear to have stalled on a monthly basis. Regionally, data were mixed across all sectors. New construction spending’s contribution to U.S. gross domestic product decreased on a quarterly basis.