Journal of Architectural Engineering

A common factor in roof failures is wind forces, which inflict considerable damage every year, even to new roof structures. Metal roofs are a popular low-sloped roof assembly. On the basis of their layout, metal roofs can be categorized as either composite or noncomposite assemblies. In North American practice, five main test procedures—ASTM E1592, ANSI/FM 4474, UL 580, UL 1817, and CSA A123.21-04—are used to determine the wind uplift performance of metal roofs. The fundamental differences between these test protocols lie in the way they represent wind effects on the performance of metal roofing systems. Of the five, CSA A 123.21-04 is the only one that assesses the wind uplift resistance under dynamic wind load conditions. To evaluate the wind uplift performance of noncomposite and composite metal roofing assemblies, eight assemblies with two different types of panels—SNAP-IT and MR-24—were tested by using the CSA A123.21-04 dynamic test protocol. By relating air intrusion characteristics of the subsurface components to panel behavior, this paper shows how composite assemblies resist wind uplift pressures better than noncomposite assemblies. This paper reveals that increased air intrusion resistance of the sub surface components in composite assemblies results in increased suction resistance, decreased panel deflection, decreased stress on the panels, and increased wind uplift resistance.

A research project was undertaken at Pennsylvania (Penn) State University to study the simulated seismic performance of Structural Sealant Glazing (SSG) used to adhere glass panels to common curtain wall framing systems. In the most common type of SSG curtain wall construction, referred to as two-sided SSG, two glass panel edges (typically opposing vertical edges) are adhered to the support framing using structural sealant, while the other glass panel edges are mechanically fastened to the support framing. In this study, full-scale two-sided SSG curtain wall mock-ups consisting of three, side-by-side glass panels were subjected to cyclic racking displacements to characterize their performance and to identify sealant and glass component failure modes under serviceability and ultimate racking displacement conditions. In addition to testing, kinematic-based models were developed to predict failure states (e.g., structural sealant failure) of the SSG curtain walls. This paper discusses the details of the predictive model and its evaluation on the basis of comparisons with mock-up test data. The model developed gives good estimates of the observed sealant failure drift. Conclusions and recommendations regarding appropriateness and limitations of the predictive model are provided.

The Randolph Tucker High School gymnasium roof failure of 1970 has received much scholarly attention. This study will provide a conclusion to a large body of previously published works by means of limit state analysis of the roof failure using state of the art parametric finite-element modeling. Parametric modeling within a general purpose finite-element analysis program allows for extremely rapid changes to the model because key terms are objects or parameters that can be adjusted internally by the program, rather than laboriously entered by the user. The failure of the roof was investigated by means of a limit state analysis, which accurately captured the cracking of the concrete and the yielding of the reinforcing steel. Concrete creep and shrinkage and relaxation of the prestressing steel were also accounted for. Finally, the authors also studied the idea that camber in the roof geometry might have prevented collapse.

Over time, the growing use of modern construction technologies with different tolerances and installation requirements for buildings has made reliance on full-size mock-ups essential for addressing the interfaces between design and construction. Three-dimensional (3D) and four-dimensional (4D) models have been introduced and developed over the past 10 years and are seen by some as eliminating the need for physical mock-ups. However, notwithstanding the recognized capabilities of digital models, mock-ups are still needed for capturing and eliciting the tacit knowledge that characterizes many construction operations, which cannot be visualized fully by the digital world. This argument is developed by illustrating the challenges experienced in the erection and testing of full-size mock-ups of curtain walls, particularly in constructability and functional requirements. It is argued that digital and physical models must be considered complementary tools in the realization of design intents.

ASTM E 1300-07 employs only two glass type factors to adjust the load resistance of annealed glass for heat treatment, one factor for heat-strengthened glass and one factor for tempered glass. The use of only two factors provides a simplistic approach that fails to utilize the full capacity of heat-treated glass. ASTM E 1300-07 differentiates heat-strengthened from fully tempered glass by the magnitude of the residual compressive surface stress resulting from the heat treating process. Furthermore, ranges of residual compressive surface stress are specified for both heat-strengthened and fully tempered glasses, suggesting the glass type factors should vary with the residual compressive surface stress. This article presents a rational method for determining the load resistance of heat-treated glass based on the residual compressive surface stress. A method incorporating previously accepted design principles with the addition of extensive data computation is advanced to calculate load resistance for heat-treated glass. With the new method including the use of 25 additional charts, designers can easily design heat-treated glass based on any value of residual compressive surface stress.

Buildability is one of the most important factors influencing labor productivity. However, an extensive search of the literature revealed a dearth of research into its effects on labor productivity of in situ reinforced concrete construction, especially on the activity levels. Rebar installation is an integral, labor-intensive trade of this type of construction material. Its walls form major parts of reinforced concrete frames, which are typically associated with a higher unit rate cost compared with other structural elements, especially spread foundations and grade and one-way elevated slabs. Therefore, objective of this research is to investigate the effects and relative influence of the rebar diameter, quantity of reinforcement installed, wall thickness, plan geometry, and wall curvature intensity, on rebar installation labor productivity of walls. To achieve this objective, a sufficiently large volume of installation labor productivity data was collected and analyzed using the multiple categorical-regression method. The results obtained show a significant influence of factors investigated on the labor efficiency of the installation operation, which can be used to provide designers feedback on how well their designs consider the requirements of the buildability concept, and the tangible consequences of their decisions on labor productivity. In addition, a set of recommendations are presented, which on implementation, can improve the buildability level of this activity, hence translating into higher labor efficiency and lower labor cost. Moreover, the depicted patterns of factors explored may provide guidance to construction managers for effective activity planning and efficient labor utilization.

In 2001, the Architectural Engineering Department at the University of Nebraska–Lincoln, along with industry partners, established an industry-experienced graduate student program. The program was developed to bring experienced design professionals to collaborate with the industry while pursuing a Ph.D. in architectural engineering. This program is designed to be mutually beneficial to industry partners, -graduate students, the University of Nebraska–Lincoln Architectural Engineering Department, and the building industry at large. The first doctoral candidate in the program graduated, and significant collaborative work was completed for the industry partner. All parties to this initial offering are pleased with the outcome and believe the benefits significantly outweigh the costs. This paper presents the program, lessons learned, and plans for the future. The authors are the faculty, the industry partner, and the graduate associated with this initial application of the program.