Journal of Architectural Engineering

The performance of conventional (helical disk) ground anchors is important to the overall quality and safety of manufactured home installations and other applications requiring anchorage to ground. This paper presents findings from an investigation of the performance of conventional ground anchors and soil index test methods in a variety of soil conditions by using a range of ground anchor types, sizes, and assemblies. The results and conclusions address variation in soil classification methods, correlation of soil index test methods to anchor performance, predictability of conventional ground anchor assembly performance, and factors affecting reliability or repeatability of test methodology. Recommendations are given to improve a proposed ground anchor test protocol and to further address significant research needs, such as the effect of seasonal variation in ground moisture on soil index tests and ground anchor performance.

The objective of this project was to evaluate system effects and further define load paths within a light-frame wood structure under extreme wind events. The three-dimensional 30- by 40-ft (9.1- by 12.2-m) building, designed to be representative of typical light-frame wood construction in the southeastern coastal region of the United States, was modeled using SAP2000. Wall and roof sheathing was modeled using SAP’s built-in thick shell element. The effect of edge nail spacing of the wall sheathing was incorporated by way of a novel correlation procedure, which eliminated the need to represent each nail individually. The computer model was validated against both two- and three-dimensional experimental studies (in plane and out of plane). Uniform uplift pressure, worst-case simulated hurricane, and ASCE 7-05 pressures were applied to the roof, and vertical foundation reactions were evaluated. The ASCE 7-05 uplift pressures were found to adequately encompass the range of uplift reactions that can be expected from a severe wind event such as a hurricane. Consequently, it was observed that ASCE 7-05 “component and cladding” pressures satisfactorily captured the building’s uplift response at the foundation level without the use of “main wind force-resisting system” loads. Additionally, the manner in which the walls of the structure distribute roof-level loads to the foundation depends on the edge nailing of the wall sheathing. It was also revealed that an opening in any wall results in a loss of load-carrying capacity for the entire wall. Moreover, the wall opposite the one with the opening can also be significantly affected depending on the orientation of the trusses. In general, it was determined that complex, three-dimensional building responses can be adequately characterized using the practical and effective modeling procedures developed in this study. The same modeling process can be readily applied in industry for similar light-framed wood structures.

This research evaluated and compared the wind-uplift capacity of wood roof-sheathing panels fabricated by using nails with retrofitted roof panels made with nails and closed-cell sprayed polyurethane foam (ccSPF) adhesive. In hurricane-prone areas, structural retrofits of light-framed wood roof structures are needed to mitigate wind damage to existing residential roof structures because the majority of these have inadequate design strength to resist hurricane-force winds. A steel pressure chamber connected to a pressure loading actuator was used to conduct uplift pressure tests on 186 roof panels. The panels were fabricated using 11.1 mm (7/16 in.) thick oriented strand board sheathing fastened to nominal 51 by 102 mm (2 by 4 in.) southern yellow pine framing members spaced 610 mm (24 in.) apart. There were 123 panels tested in typical as-built conditions, and 63 panels tested after they were retrofitted with ccSPF. The parametric study determined the effect of several factors on wind-uplift failure pressure: (1) three nail types, (2) two nail spacings, and (3) three retrofit methods using ccSPF. The hypothesis tested was that ccSPF (traditionally used as wall and roof insulation in houses) could also act as a structural adhesive to increase the wind resistance of existing roofs. Standardized tests do not currently exist for wood roof panels, and so a uniform, static pressure-test protocol was developed on the basis of the ASTM E330, Method B Test Procedure. The results showed that ccSPF retrofits increase the wind-uplift capacity of the pre-1994 code-minimum wood roof panels by as much as 250–300%. This finding is important because it could provide a means to improve the wind resistance of these older roof designs, which may still account for more than 60% of the existing residential inventory. The distributions of roof-failure capacities of as-built and retrofitted roof panels are presented, and statistical parameters are presented for use in developing performance-based design criteria. The documentation and approach is presented as a model test protocol as the basis of a standardized wind-uplift test method for wood roof-sheathing panels.

This paper serves as a resource to prefabricated construction managers who are attempting to implement lean thinking to improve their production operations by eliminating waste. Lean is both a general way of thinking and a specific production management approach that emphasizes using less of everything to satisfy the customer by delivering the highest quality at the lowest cost in the shortest time. While providing an overview of lean principles, this paper focuses on two fundamental lean concepts, standardization and continuous flow. To develop these concepts, this paper uses a case-study approach to describe the experiences of a large homebuilder confronted by rising production costs as they migrate wall-building operations from the construction site into a factory. Lean production principles are successfully applied, yielding a 47% increase in productivity and a 25% reduction in lead time. This study also found employee involvement and the supplier relationship as key factors for successful lean implementation. Challenges that limited implementation success and the related lessons learned are also presented.

Accommodating the preference of the growing elderly population to age independently, at home and in the community, requires innovative and cost-effective neighborhood retrofit plans. Retrofitting existing homes and infilling available neighborhood land parcels with “smart homes,” equipped with technologies that enable monitoring and assessment as a means of ensuring the quality and efficiency of home care and health care provision, is intrinsic to these efforts. Blueroof Technologies, Inc., in McKeesport, Pennsylvania, has developed and demonstrated a number of in-home and neighborhood-scale technologies and is working with the local McKeesport municipality to restore an economically distressed neighborhood to accommodate successful aging in place. This paper describes the Blueroof “BlueNode,” “BlueKiosk,” “Smart Cottage,” and “McKIZ,” a McKeesport neighborhood restoration initiative, which incorporates the use of smart cottages and neighborhood-scale interventions to address the housing challenges of an aging population. The technologies and neighborhood retrofit methods described in this paper could serve as a cost-effective template for restoring low- to middle-income neighborhoods to enable successful, mixed-generation aging in communities domestically and abroad.