Journal of Architectural Engineering

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.

Three-dimensional (3D) printing technology is increasingly playing an essential role in the customization of prefabricated buildings. To demonstrate its high-quality, cost, and time-saving advantages, this paper first presents a technical analysis of prefabricated formwork-making using 3D printing. Then, we compare 3D printing to the two conventional methods of manual wood and computer numerical control (CNC) foam using a demonstration house with curved walls specially designed and constructed using these three formwork-making methods. We concluded from our comparison that the 3D-printed polymer-based formwork-making method performed best in accuracy and time, and generated greater cost-effectiveness than did the manual wood and CNC foam formwork-making methods for the mass production of customized prefabricated buildings. Lastly, this paper provides design guidelines for architects to help achieve the highest economic savings and efficiency in customized prefabricated formwork utilizing the 3D printing method.

Design and construction professionals must make well-informed decisions for every project that meets both industry standards and building codes and also the specific needs of building users and clients. In order to make effective decisions, research suggests that explicit knowledge, defined as easily codified and communicated information, and tacit knowledge, considered to be the know-how of completing a task, must be effectively applied. While there is recognition of the need for both forms of knowledge, architecture engineering and construction (AEC) education has historically focused on covering content-related explicit knowledge in the classroom. As a result, students generally develop tacit knowledge over their careers. Due to an aging AEC workforce, there is a need to support tacit knowledge development in the classroom to enable students entering the industry to supplement the collective tacit knowledge that will exit the industry as the current generation of practitioners retires. Therefore, the authors of this paper explore the use of augmented reality (AR) and virtual reality (VR) to provide immersive virtual experiences aimed at replicating the types of scenarios that students might experience in their careers that would require them to apply tacit knowledge. The authors tasked students in construction-related disciplines with assessing a building design and making judgments about how the design should be modified to support an occupant in a wheelchair in both VR and AR. Using two similar models and a counterbalanced research methodology, the authors coded the statements and behaviors of the student participants during this design assessment exercise. The results of this work indicate that both technologies elicited statements that were indicative of explicit knowledge related to the needs of a wheelchair-bound occupant. When AR and VR were found to directly encourage physical exploration in the experience, both led to behaviors that simulated the completion of tasks that might be performed by a wheelchair-bound occupant. These behaviors were frequently followed by comments that were indicative of tacit knowledge. While this type of behavior was observed in both AR and VR, AR seemed to more directly encourage this type of interaction among participants. The contribution of this work is in providing observational evidence to demonstrate how the physical exploration affordances of AR and VR may be able to support experiences that foster the use and development of tacit knowledge related to AEC-related decision-making.

Increases in fossil fuel usage and energy consumption have become important issues in most countries of the world. Recent statistics show that the building sector is the main contributor to the world total energy consumption, which makes it responsible for a significant amount of greenhouse gas emissions. Several studies have been carried out to design buildings focusing on reducing their energy consumption and improving occupants’ comfort. This study focused on the impact of parameters influencing the seasonal transition periods (STPs) and annual energy consumption through numerical simulations in residential buildings. For this purpose, the thermal performance of six different wall constructions with similar U values under different ventilation rates was investigated. In addition, the effect on building heating and cooling loads during spring and autumn STPs in buildings with diurnal occupation patterns in hot, arid climates was studied. A small building located in Tehran, Iran, was selected as a case study model and simulated as the reference building. The results showed that Wall 4 with an effective surface mass of 249 kg/m² had the best performance in reducing energy consumption and had a significant effect on STPs. When Wall 2’s ventilation rate reached 10 ach (air changes per hour), its impact on STPs was significant within the 60 days of the autumn transition period. The effect of natural ventilation on STPs was minimal for Wall 4. It was also found that a 5 ach ventilation rate was the most appropriate for this period.

The estimation of seismic forces for acceleration-sensitive nonstructural components (NSCs) in buildings including architectural, mechanical, and electrical systems and building content requires a reliable prediction of the seismic floor accelerations along the building height. These accelerations can be estimated either by performing detailed time-history dynamic analyses on a finite-element model of the supporting building or by using simplified equations as proposed in the North American and European codes. In addition, a probabilistic estimate of floor acceleration demands is essential for risk-informed performance assessment and loss estimation of these NSCs. To this end, an analytical method for the prediction of peak floor acceleration demands was proposed in FEMA-P58 [ATC (Applied Technology Council). 2012. Seismic performance assessment of buildings, prepared for federal emergency management agency. FEMA-P58. Washington, DC: ATC] based on linear and nonlinear time-history analyses performed on idealized low-to-medium-rise building models. This paper presents a validation study of the FEMA-P58 equation using two databases of recorded horizontal rooftop accelerations in 41 instrumented buildings. The first database consists of 28 buildings that were subjected to different earthquake events in California, while the second database consists of 13 buildings that were subjected to the 2011 Tohoku earthquake in Japan. The ratios of the recorded rooftop-to-ground-level accelerations in both databases were computed and compared to the FEMA-P58 predictive equation. A comparison of predicted versus recorded median and dispersion of the rooftop acceleration amplification was made and discussed. The results showed that the equation underestimated the acceleration amplification for frame buildings.

Architectural glazing designers in the United States and many other parts of the world use prescriptive methods to determine the load resistance (LR) of glazing and glazing constructions in buildings based on a probabilistic theory of glass strength. This theory is known as the glass failure prediction model (GFPM). The GFPM relates the probability of breakage to surface stress magnitude induced by lateral uniform loads acting on the glass as well as the duration of stress. Glass design charts in US model building codes and standards use a nonlinear finite difference model developed during the early 1980s as the basis to determine surface stresses induced by lateral loads. The primary analysis tools available to engineers today are based on the finite-element method and not on the finite difference method. The authors developed a nonlinear finite-element model and applied the GFPM to the nonlinear finite-element model output to determine the probability of breakage for selected glass lite geometry and load combinations. The results of their analyses compare favorably with values in model building codes and standards. This model will facilitate architectural glazing designers when they must design glazing for fenestrations that charts in model building codes and standards currently do not address.

An arch is a basic structural form and has been used extensively in antiquity to create openings, doorways, vaulting, buttressing, bridges, and aqueducts. Most arches are built with masonry, especially those in the past. Masonry is largely a compression material. Tensions will lead to cracking, and eventual deterioration of the arch or vault. However, catenary arches are unique structural forms, characteristically having a pure compressive shape and are, therefore, ideally suited to masonry. Thrust-line equations are derived for the catenary arch subjected to uniform loads (i.e., self-weight), which is based on the original hyperbolic function for catenary shapes. A second solution is also given—a numerical procedure composed of elements or segments. Elements are formulated to predict a pure compressive shape for any number and orientation of point loads, applied externally to a catenary arch. The thrust-line equations provide an exact solution for uniform loading, but the solution for point loads is approximate. The accuracy of the point load method is determined by the number of elements. However, the point load method is unique, in the sense that the catenary arch is grown from a single element to create a pure compressive shape. This is achieved by continuously adding elements to the model until the shape of the arch is defined. Despite being an approximate solution, the point load method was found to converge to the exact solution. The point load method may also be used to determine the thrust-line path in other arches (i.e., circular, parabolic, etc.). Example solutions are provided.

Over the past 10 years in Europe and North America, passive house standards have become the leading high-performance building standards. Although site energy metrics are paramount in these standards, the roots are in reducing carbon emissions. This article describes the influence that using regional, rather than broad (i.e., continent-wide), energy supply carbon emission factors can have on the life cycle operating carbon emission outcome for single-family dwellings designed according to a passive house standard for three climatic locations across Canada, using two mechanical systems with different fuels. All three cities significantly differ when using regional carbon emissions factors, compared with a broad average. Recommendations are made to generate a hybrid carbon intensity factor balancing national and regional electrical grid carbon intensities. As the passive house standards become more and more mainstream paths to reducing the carbon impact of buildings, understanding the differences between emissions factors becomes increasingly important.

A noniterative procedure to determine the retrofitted configuration of an existing building, to be assessed according to the seismic code, is proposed. Among possible rehabilitation strategies, the approach involving both stiffness and strength increments has been followed, maintaining yielding and ultimate displacements unchanged. Limiting our focus to low-rise reinforced-concrete buildings, under the hypotheses of shear-type behavior and constant axial forces in the columns, the yielding and ultimate displacements of a single-degree-of-freedom (SDOF) system, equivalent to the existing multi-degree-of-freedom (MDOF) system, are determined. Using the SDOF displacement capacity, the displacement design spectrum furnishes the corresponding period and, then, the required stiffness and strength are determined. Hence, returning to the MDOF system, the demand at each floor in terms of shear resistance can be assessed. The difference between required and available shear resistances is provided by additional elements, in this case steel bracings are adopted. The discussion of a case study clarifies the various steps described, also confirming the suitability of the assumptions introduced, with special attention paid to the vertical regularity of the whole structure or of the added elements alone. Moreover, nonlinear dynamic responses to a set of natural accelerograms are used to evaluate the effectiveness of the proposed approximate design procedure.

This study investigated the effects of inorganic silicone coatings on the load resistance of heat treated glass beams. The authors performed destructive load tests on 192 heat treated glass beams divided into 6 samples. Three samples consisted of heat strengthened glass and three samples consisted of fully tempered glass. For each glass type, one sample consisted of clear glass, i.e., no coating, and the other two samples had different types of silicone coatings. The authors analyzed the failure data from the samples. The data indicate that the silicone coatings did not adversely impact the load resistance of the heat treated glass, and in the heat strengthened samples, the silicone coatings apparently increased the load resistance of the glass beams.

High-performance building envelopes are designed to achieve target reductions in operational energy (OE). However, these wall assemblies often require initial, upfront investments in material cost and manufacturing energy. To this end, this study assessed the total life cycle energy (LCE) and life cycle cost (LCC) of five Passive House–inspired building envelopes in the United States via life cycle assessment (LCA) and life cycle cost analysis (LCCA), respectively, across four US climate zones. The results indicate that, regardless of climate, wood-framed wall systems were most cost-effective and exhibited lower LCE and LCC compared with the other wall assemblies investigated herein. Double-stud walls in particular were found most environmentally and economically cost-effective in all climates. In addition, the results specifically highlight the law of diminishing returns in terms of OE reduction through more insulative envelopes, as the impacts of embodied energy (EE) outweighed the benefits of a reduced OE in some cases. Finally, depending on climate and building archetype, the total EE of the residential buildings accounted for 22%–91% of the total LCE over a 60-year period—a result that highlights a grand opportunity to reduce the EE and, thus, total LCE of high-performance residential construction in the US.

This article features modular multistory timber construction in a benchmark-based approach. It first contextualizes the use of timber from the first human societies to today’s sustainable construction solutions. It then typifies modular component concepts and systems, debating possible modular architectural briefs, appealing for implementation in the emergency sheltering niche, which although already rehearsed in Europe, could take further advantage of transportability and stacking capabilities. Through a comparison of 10 modular timber construction case studies, various potentials are cataloged as an operative design showcase.

The architectural heritage of the 1950s, mainly built in reinforced concrete, currently presents serious problems of degradation in the structural members more exposed to environmental aggressiveness. One cause of degradation of the porous material is the presence of sulfates in the water whose crystallization causes microfractures inside itself with subsequent detachment of surface layers. It is important to be able to predict the evolutionary trend of such damage on the basis of the composition of the concrete in order to improve its performance. The uncertainties inherent in the phenomenon of degradation suggest a probabilistic approach to this problem. Therefore, to study the decay produced by the presence of sulfates in concrete structures, accelerated durability laboratory tests on concrete specimens were carried out. This decay, quantified in a laboratory through a laser-triangulation profilometer, provided the basis on which a probabilistic modeling of the evolution of durability over time was developed.

To meet the ever-increasing demand for more environmentally conscious building designs, it is important that sustainable building material options be available. Natural and recycled materials can be used in sandwich panels to reduce their environmental footprint. This study featured experiments with 12 sandwich beams constructed with flax fiber–reinforced polymer (FFRP) faces and recycled corrugated cardboard cores under monotonic and impact loading. Each sandwich beam was 1,200 mm long and 150 mm wide, and was constructed of two-layer FFRP faces and a 75-mm-thick corrugated cardboard core. Six specimens were prepared using a plain cardboard core and six with a waxed cardboard core. Two separate test methods were employed in this study: a three-point bending test and a drop-weight impact test. Three specimens of each type with a span length of 1,120 mm of each type were tested under monotonic load. The load was applied through a 150-mm-wide steel hollow structural section (HSS) and was measured with a 250 kN load cell. The midspan deflection was measured with a string potentiometer, and the strains in the top and bottom faces at midspan were measured using strain gauges. The monotonic test data were recorded at a rate of 10 Hz. Three specimens of each type were tested under a drop-weight impact load. The drop weight was applied to the midspan. To match the monotonic tests, the drop weight was affixed with a 150 mm HSS loading surface. The midspan displacement was measured with a fast-action string potentiometer, and the midspan face strains were measured using strain gauges. The impact data were recorded at a rate of 25 kHz. In addition, each impact test was filmed with high-speed video (500 frames per second). The residual monotonic flexural behavior after impact was also investigated for specimens that survived the impact testing (that is, they were additionally tested under monotonic three-point bending). The results of the tests were compared with the results of similar tests on sandwich beams with conventional petroleum-based foam cores and showed that the cardboard core beams behaved similarly to the foam core beams. It was determined that core manufacturing and specimen preparation had a significant effect on the overall specimen behavior and potentially caused premature failure in some of the tests. The residual monotonic tests of the specimens after impact showed that there was no significant reduction in specimen strength or stiffness after an impact event. Existing models used for predicting the behavior of foam-core FFRP sandwich beams were used to predict the behavior of the cardboard specimens tested in this study.

The paper shows the results of analyses of the behavior of an innovative subcomponent made of two glass shells and a plastic thermal belt interfaced with a resin-based adhesive, in order to define the plastic material–adhesive combination able to guarantee compliance with the requirements related to mechanical strength, thermoacoustic insulation, dimensional stability, material compatibility, and durability. Two different types of ultraviolet (UV)-curing adhesive were used to establish the best plastic–adhesive combination. A study of the mechanical behavior and the reliability over time of the bonded assembly was conducted by performing accelerated weathering tests and tensile tests on 30 specimens. The laboratory tests were performed using single-lap-joint specimens in accordance with the ASTM D1002, ASTM D3163, and ISO 4587:2003 standards. At the end of the accelerated weathering tests, it was possible to observe that the stress conditions simulated during the seasonal cycle inside the climatic chamber led some specimens to failure, without affecting others. To quantify, in real terms, the performance of the two analyzed adhesives over time, it is necessary to expose new specimens to the natural weathering effects induced by the environmental conditions for a duration of at least 1 year. Future studies would be useful for exposing new specimens to new seasonal cycles developed using the parameters of different climatic contexts than those used until now. This paper demonstrates the use of an innovative resin-based adhesive for gluing plastic and glass subcomponents together.

One of the most fundamental issues in modern architecture is the provision of indoor illuminance using daylight, especially in the deep spaces that are far from the openings. In nature, organisms are equipped with some unique strategies to manage light for survival. Nature consistently considers the optimal response to take advantage of environmental conditions. In the present study, reflecting superposition, the process of lobster vision in directing light toward the retina, is investigated as an optimal solution for directing light through architectural space. First, the function and structure of a reflective superposition eye are studied and practical biological principles are extracted from relevant biological databases. Then, these extracted principles are applied in the design of reflective louver, and considering the climatic and operational parameters, the process of simulation and parametric design of the reflector louver is described. Finally, the data extracted from simulation stage are evaluated and directly compared to the base state. The results indicate an appropriate performance of the designed louver in improving atrium illuminance.

The University of Texas at Austin’s (UT-Austin) Civil, Architectural, and Environmental Engineering (CAEE) department has taken several steps toward improving the preparation of architectural engineering students with respect to modern engineering tools, including the computing tools commonly used in engineering practice. This is most evident in the integration of building information modeling (BIM) throughout the architectural engineering (ARE) undergraduate program curriculum, from early design (building envelope design/massing), to integrated engineering systems design (structural and mechanical integrated with architectural design), and analyses beyond design, such as scheduling and cost estimating. BIM was identified as a unifying aspect of the ARE curriculum. Starting in fall 2008, the ARE faculty began to introduce BIM into the ARE curriculum one year at a time, starting with the freshman year. By fall 2011, it had been introduced into our capstone course, ARE 465. In 2013, an entire course entitled ARE 376, Building Information Modeling for Capital Projects, was added to the curriculum as a technical elective. The introduction of BIM into the ARE program is intended to improve the preparation of students with respect to design, including the computing tools commonly used in engineering design. This paper describes experiences of UT-Austin’s CAEE department in implementing BIM across the ARE undergraduate curriculum, carried out over a period of 10 years. Implementation steps, courses affected, and lessons learned to date are documented.

The conservation and maintenance of earthen buildings is crucial, especially when dealing with heritage sites. This normally involves considerable effort in preliminary studies, which must be well planned in order to efficiently manage any restoration. This case study proposes a methodology to briefly assess the current state of a historical rammed-earth wall, to bring to light specific information regarding approaches for subsequent studies or decisions. This methodology is based on the study of damage and risk as a tool to swiftly discern critical areas or issues needing immediate attention. The procedure is illustrated on an outstanding heritage building: the Alcázar of King Don Pedro I in Carmona (Seville, Spain). Our conclusions confirm that this methodology constitutes an efficient and straightforward means to obtain not only a preliminary assessment of rammed-earth walls, but also objective and useful criteria for decision-makers.

Cross-laminated timber (CLT) is composed of a series of lumber layers placed orthogonally to create a thick panel. Advantages of CLT construction include reduced construction time, lighter structural elements, and reduced carbon footprint. As part of an effort to explore the use of a southern pine CLT panel for building code acceptance, the transmission loss (TL), associated sound transmission class (STC), normalized impact sound pressure levels (NISPL), and associated impact insulation class (IIC) of CLT walls and floors were measured. Wall and floor configurations were tested both as bare CLT panels and with one side covered with studs/joists, insulation, and gypsum wall board. STC results of the bare wall and floor configurations produced identical STC values. The wall and floor configurations using CLT with one-sided studs/joists met or exceeded the STC values in the International Building Code (IBC), but did not meet the IIC values in the IBC. Comparisons of the one-third octave band TL of the CLT panels with conventional wood frame and concrete sections were discussed. The TL performance of the CLT panels mirrored the mass–law relationship. The NISPL associated with CLT bare floors mimicked the NISPL values of a bare concrete floor, except at higher frequencies at which the CLT outperformed the concrete.

An empirical approach for the analysis of energy consumption of existing buildings of the tertiary sector is presented in this study. It allowed the organization and management of large amounts of data according to different timeframes and helped to focus on leading issues about energy uses, and dealt with compatibility with tariff structure. The analysis method, which implied a powerful graphical representation of the results, allowed us to detect critical issues in electricity energy management for public buildings and improve their energy performance. Furthermore, the authors proposed a set of electricity consumption indexes (ECIs) that gave useful insight into the main hotspots. The basis of the proposed method was an automated spreadsheet based data processing procedure. The main advantage of the method was its applicability with a small charge due to the purchase and installation cost of simple data loggers instead of more complicated and expensive technical building management systems. The method was tested exploiting data measured for more than 2 years in several buildings of the Politecnico of Milano (Italy) university.