Journal of Architectural Engineering

Out-of-plane loading of trusses occurs when a horizontal force is applied to the truss perpendicular to the plane of the truss. Because trusses are not specifically designed for lateral loading, the behavior of trusses during construction before adequate bracing is installed is unknown. Examples of out-of-plane loading include wind and seismic forces, as well as forces from fall-arrest anchors attached to trusses during construction. The purpose of this paper was to measure the maximum load and rotation of a single truss exposed to a horizontal out-of-plane load applied by a fall-arrest anchor. A specialized testing fixture was used to apply a horizontal load to a single unbraced truss attached to two stem walls, representing a typical construction application. A set of monoslope queen-post trusses with two different pitches were used, and load was applied at both the truss eave and peak. Maximum loads for a single truss were much less than the expected 8 kN required to act as a personal fall-arrest anchor. The maximum moment was similar for trusses with different pitches. Rotational stiffness of the eave loadings was the result of truss rotation at the truss–wall connection. Rotational stiffness decreased as truss pitch increased. Analysis of out-of-plane loading should include the rotational stiffness of the truss–wall connection.

High wind-induced suctions cause significant damage in traditional roofing systems, leading to subsequent rain intrusion and loss of interior contents. Damages include, among others, failure of tiles or shingles and in many roofing systems are related to workmanship-related issues, such as inadequate spacing of nails or poor application of foam adhesive. This paper proposes a new composite roofing system, which consists of large precast concrete structural panels designed to replicate the architectural shape of high-profile roof tiles. The system allows the components and cladding (C&C), usually placed onto the structure, to be incorporated into the main wind force resisting system (MWFRS). The roofing panels, therefore, serve both as a structural system and as an architecturally pleasing building envelope. As a first step toward the full development of the proposed system, full-scale tests were performed to evaluate its system-level structural performance, including its connections. The results are used to predict the system’s strength and serviceability capabilities. Tests under a combination of loading scenarios simulating high wind-induced pressures indicated that the structure performed well under extreme wind-induced loading. The test results were used to develop tables containing design data for the new roofing system for buildings located in various geographical regions. In addition, a preliminary cost estimate was performed. The paper lists recommendations for future research, including testing of the proposed system aimed at developing and assessing the system’s performance under wind-driven rain, its energy efficiency, and its noise-reduction properties; performing detailed and comprehensive cost estimates; and exploring the potential of alternative roof shapes and configurations.

Precipitation is one of the most common moisture sources on which building designers focus. Water comes from both top down and bottom up. Although foundations are sometimes constructed out of pressure-treated lumber, generally they are constructed from poured concrete. In a wet climate zone, the foundation of a house is often under continuous contact with moisture, which is mainly caused by rundown rainwater, wet soil, a high water table, or a combination of all these factors. This causes rot growth and decay of the wood-frame structure as it sits constantly on the damp foundation concrete. In this research, moisture transfer between concrete and wood is investigated under three different scenarios: a case with direct wood and concrete contact and two cases with different moisture barriers between the two materials. The moisture barrier materials considered in this study are the damp-proofing layer and sill plate gasket. The moisture transfer processes in these three cases are investigated in a field experimental setting using a customized experimental setup for 1 year. The experimental data suggest that using damp proofing and a sill gasket helps restrict moisture transfer.

Following natural disasters, major changes are often adopted in design codes, provisions, and guidelines that highlight existing or perceived deficiencies in design code calibration and sometimes design philosophy. The work presented herein chronicles the evolution of seismic design for wood-frame buildings from 1959 through current state-of-the-art methodologies available as of 2015. Included in the approaches in this study were two performance-based seismic retrofit levels and a soft-story-only retrofit design that followed a recent guideline published by FEMA. A brief background on the historical significance and major changes adopted in each provision or guideline is provided. Building performance was quantified and compared using multirecord fragilities for a range of wood-frame building types for the historical seismic provisions, demonstrating that the predicted seismic performance of wood-frame buildings has improved over time. It was also demonstrated that performance-based seismic retrofits can be designed to multiple levels of seismic performance, including a superior level, which provides immediate occupancy of all building types following maximum considered earthquake (MCE) ground motions. The superior-level retrofit reduced the predicted peak interstory drift of a 3-story soft-story building by 90%. The information gained in this study can be incorporated into community loss estimation models and used to expand the knowledge base on how seismic risk has changed over time with respect to the wood-frame building inventory.

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

Construction technology advancements in the last couple of decades have led to the use of lightweight and high-strength materials in structural systems. Although longer spans and lighter materials result in floor systems with less mass, stiffness, and damping, the trend toward a paperless office decreases damping and the amount of live load on the floors even more. Consequently, structures have become more vulnerable to annoying vibrations, and vibration serviceability has become an area of serviceability concern. For vibration serviceability calculations, the damping value of the structural systems is a critical parameter. Damping in structures has proved to be dependent on the amplitude of the applied force on the structure. This condition is referred to as nonlinear damping, or amplitude-dependent damping. Although damping is constant at low and high amplitudes, for in-between amplitudes, the damping value increases with the levels of excitation amplitude. For wind and earthquake excitations, the amplitude-dependent characteristics of damping have been studied extensively in the literature. For floor vibration serviceability applications, even though the nonlinear behavior of damping has been accepted to exist and mentioned in some publications, it is not closely looked at or discussed in detail. The floor vibration serviceability calculations are very sensitive to damping values, but vibration serviceability researchers and practicing engineers are often uncomfortable with assigning a specific number as a damping ratio for a specific mode because of the inconsistency of damping values obtained from different methods. This paper presents a closer look at the amplitude-dependent damping in vibration serviceability and focuses on a laboratory footbridge with experimental and analytical studies. The laboratory footbridge was studied extensively with static and dynamic tests. Three-dimensional finite-element (FE) models were developed, updated, and fine-tuned for two bottom chord extension configurations for both static and dynamic tests. The amplitude-dependent damping behavior of the laboratory footbridge is shown for different amplitudes of sinusoidal excitations. The amplitude-dependent damping ratio values obtained from effective mass calculations proved to be correct with the FE model acceleration predictions. The FE model predictions successfully matched the test results with the nonlinear characteristic introduced for modal damping. One of the most difficult tasks in vibration serviceability research is matching the measured acceleration responses with the FE models, and the success of this paper in matching the acceleration responses for various levels of excitations (with corresponding amplitude-dependent damping values) with the FE model is unique. Successful verification and clarification of the amplitude-dependent phenomenon and FE model matching of measured acceleration responses reinforce the confidence in the FE models in vibration serviceability research by showing that the FE models are reliable not only for natural frequency predictions but also for acceleration response predictions.

The construction industry is responsible for more than 40% of the carbon emissions in the United States. These emissions are generated by energy, water, and materials consumed at different stages of the construction, maintenance, operation, and disposal processes and during the recycling and reusing of construction components as materials or biomass. Carbon-emission modeling is a complex procedure of process and footprint integration for different components either directly and indirectly associated with a service, product, material, or system at different phases. Prior research focused on each phase separately and/or supplemental information from alternative sources because of the lack of available data and information. Even though there are comprehensive lifecycle models covering every phase of a project, these models do not integrate existing models. The purpose of this study was to develop a comprehensive framework of building lifecycle carbon-emission modeling that would integrate existing models, information, and data. This research integrated prior models and methods, incorporated multitier mechanisms, and developed flexibility within the model so that reliability would be improved for measuring, tracking, and quantifying carbon- and environmental-related features, factors, and variables. This paper discusses the first phase of the research, model development, and testing.

Despite the use of earthen materials in building construction for thousands of years, many engineering properties of earthen walls are not well understood, documented, or regulated. California and New Mexico have adopted building codes allowing earthen structures through prescriptive methods that rely on rules of thumb to limit heights and spans of construction. Furthermore, California restricts earthen structures to very limited areas on the basis of soil type. Overall, the prescriptive methods have led to uncertainty about reinforcing requirements. There is a belief among builders who use earthen materials that reinforcement is required only in areas of high earthquake hazard, implying that a geographic area is either seismic or not. In reality, all locations are prone to some seismicity. On the basis of the probability of seismic activity and soil conditions at each locale, every site has a risk that ranges from very low to very high probability of earthquake damage. Energy compliance and structural adequacy are two areas of concern to city officials. This article delineates the processes required to build with compressed stabilized earth blocks (CSEBs) within the building code. The authors determined that the compressive strength of CSEB walls is sufficient in most residential applications, but wall shear strength is more critical. To determine the wall in-plane and out-of-plane shear strength, the authors conducted laboratory tests to investigate the shear strength of CSEB wall assemblies, first without reinforcing (which proved insufficient) and then incorporating geogrid (sometimes referred to in the industry as geofabric) on interior and exterior wall surfaces as a method of lateral reinforcement. The resulting unreinforced wall shear strengths were used to determine where unreinforced CSEBs can be used to meet code strength requirements. The following data demonstrate that CSEBs are viable material for residential construction but are acceptable only for use in limited areas without reinforcing due to assembled wall mass and the seismic loads they create. In addition, this article reviews the energy-compliance process required when designing earthen structures.

Nonstructural systems are responsible for the majority of national loss suffered during earthquakes, and suspended ceilings with acoustic lay-in tiles are among the most significant—and most vulnerable—of these nonstructural systems. Expensive full-scale experimental shake table tests are generally preferred over mathematical modeling techniques for simulating the seismic performance of these suspended-ceiling systems. Because of this traditional reliance on shake table testing, there is currently no experimentally validated finite-element model of suspended-ceiling systems. This paper addresses this crucial knowledge gap by introducing the first experimentally validated computer simulation of suspended-ceiling systems and by establishing a modeling methodology for future numerical studies. This study is the first to use finite-element modeling for a heterogeneous system (in this case, ceilings composed of loose components). This project aimed to develop (1) the feasibility of combining finite-element modeling of suspended-ceiling systems with current seismic simulation tools; (2) a system for validating the numerical model of the suspended ceiling with system-level shake table tests; and (3) the possibility of using the validated numerical model as a substitute for expensive shake table tests.

Evidence-based design (EBD) studies have grown rapidly over the last decade, attempting to link traditional building design to building occupants, with a particular emphasis on healthcare settings. Additionally, there has been an increase in green building design (GBD) for most new construction; however, the effects of GBD on the use phase and occupant health is not well studied. This study captured the impact of both EBD and green building strategies by analyzing different metrics across a 3-year period for the same unit (oncology) spanning the traditional hospital (Unit 2800) space and the new green addition (Unit 5800). Of the six categories analyzed, quality of care, productivity, and utilities all stayed relatively unchanged from Unit 2800 to Unit 5800, with a slight decrease in number of staff needed due to a lower census. Expenses, staff satisfaction, and patient satisfaction saw a general upward trend from Unit 2800 to Unit 5800. As the green building industry continues to grow, quantitative analysis on occupant satisfaction and EBD, such as this study, can inform designers and healthcare providers on the impact of their green design decisions.

The authors performed an experimental study with weathered fully tempered monolithic glass loaded to failure under controlled conditions. The 14 specimens in the study originated from the northeastern United States. The specimens were loaded with monotonically increasing pressure until fracture occurred in accordance with the ASTM E997 test method. The recorded failure load time histories were converted to equivalent 3-s failure loads using a modified load-transformation-integration method that incorporates residual compressive surface stress. Variations of the residual compressive surface stress measurements are presented for each specimen, and the effect that the variations in residual compressive surface stress have on the equivalent 3-s failure load calculations are also explored. Equivalent 3-s failure loads are shown to be proportional to the measured residual compressive surface stress. The equivalent 3-s failure load is compared to the load resistance calculated using ASTM E1300, and the modified method for treated glass is presented. The mean equivalent 3-s failure loads were 150% larger than the load resistance calculated using ASTM E1300 and 50% larger than the load-resistance predictions of the modified method, which suggests that fully tempered glass is stronger than predicted by ASTM E1300 and does not weather like annealed glass.

Demographic trends predict a shortage of engineers, with women being one group targeted to fill this gap. Although the percentage of engineering degrees attained by women has increased, there has not been an equal increase in the number of women working in the industry. This means that women are either leaving the industry after they enter or not entering at all. The purpose of this study was to identify what can be done in the education of female engineering students to better prepare them for the engineering workforce reality and culture. A survey was conducted to collect information from female architectural engineering students about their perception of the industry. The results were then compared to the actual conditions of the workforce. The goal was to identify areas of discrepancy between perception and reality so that these areas can be addressed before students enter the workforce. The hope is that, with a better understanding of their career environment, women will be better prepared to deal with the issues that may cause them to leave the industry.

Geotechnical engineers have reported that, in the foundation design of buildings with a deep basement, the weight of the soil removed for basement construction could be discounted from the foundation load. Substantial savings were achieved for a 22-story office building with a 2-level basement, for which the design of the pile foundation utilized this concept of compensated foundation. Subsequent site monitoring of selected column settlements showed that the total and differential settlements, angular distortion, and deflection ratio of the building were well within the allowable limits. Detailed information on the compensated foundation design is presented.