Building Configurations Research Articles

Investigation of the Reynolds number independence of cavity flow in 2D street canyons by wind tunnel experiments and numerical simulations

The Reynolds number independence (Re independence) criterion of Re > 11,000 is widely adopted to fulfill the dynamic similarity between the urban flow modeling and the down-scale measurements. However, for 2D street canyons with H/W ≥ 1.5, experiments, numerical simulations, and in-situ observations have reported different vortex-flow regimes with similar building configurations but at different scales. This study uses both wind tunnel experiments and numerical simulations to revisit the Re-independent flow regimes and Re independence criteria with an extensive Re range for idealized 2D street canyons with various aspect ratios (H/W = 1.1, 2.4, 3, 4, and 5). We introduced an optimized ratio of relative changes (RRCs) to evaluate the flow regimes’ similarity. The wind tunnel experiment confirms that the cavity flow with H/W = 1.1 meets the Re independence when reference building Re (Reref) exceeds 11,000. Simulations validated by the experiment results are conducted to investigate detailed flow regimes and the critical Re (Rec) range for each aspect ratio. The canyons with H/W = 2.4, 3, and 4 are dominated by a single asymmetric vortex when the Re independence is satisfied, while there are two vertically-stacked counter-rotating vortices in the canyon with H/W = 5. The value range of Rec increases with aspect ratio from 1.9 × 104–2.6 × 104 (H/W = 2.4) to 1.3 × 105–2.1 × 105 (H/W = 3), and 2.1 × 106–6.4 × 106 (H/W = 4 and 5). Our results indicate that the fully Re-independent flow regimes in deep canyons have fewer vortices than the literature value with down-scale experiments and simulations. The variant Rec with different aspect ratios suggests the requirement to conduct the Re-independence test for different model configurations.

Amplification of seismic demands in inter-storey-isolated buildings subjected to near fault pulse type ground motions

Inter Storey Isolation (ISI) shows promise for seismic vibration control in relatively tall buildings. With proper design, an ISI system isolates the upper storey block (USB) and emulates the effect of a nonconventional Tuned Mass Damper (TMD) on the Lower Storey Block (LSB) to reduce the seismic responses considerably. The vulnerability of conventional Base Isolation (BI) under pulse type motions was reported in the past. This study demonstrates the adverse effect of pulse type motions on the performance of ISI systems. An inclusive set of building configurations and bearing typology for the ISI system are employed and are subjected to two suites of unidirectional pulse and non-pulse type ground motions pertaining to varying hazard levels. Extensive nonlinear dynamic analysis of the frame-ISI systems are carried out. Representative statistics of the pertinent responses from each suite are contrasted to demarcate the effect of pulse type motions. The pulse type motions are shown to degenerate the efficiency of an ISI system to significantly amplify the seismic demands (and associated uncertainties) by allowing transmission of low frequency components (reminiscent of pulse(s)) to the response time histories. Response-specific amplification factors for the demands are assessed. The FEMA suggested guideline is shown to severely underestimates the bearing displacements, which is potentially dangerous. This deficiency is addressed by suggesting a modification factor in the FEMA formulae. The influence of the pulse period, mass ratio, damping in the bearing and hazard levels on the amplification of demands are discussed. However, this investigation considers a limited number of framing systems and isolation bearings subjected to a limited number of ground motions, which may be expanded in future study.

Simplified modeling and analysis method for skyscrapers with outrigger system

In this paper, a simplified modeling and analysis method for skyscrapers with an outrigger system is introduced. The simplified method is mainly based on the superelements and dominant degree of freedom methods, and it is codified by using MATLAB software. The simplified method results are verified with analysis results of the ETABS detailed model, where static, modal, and dynamic analyses are conducted. The proposed method's applicability on different configurations of tall buildings with outriggers systems is also verified through a parametric study. A comparative study with some previous studies is conducted to prove the efficiency of the proposed method. It was found that the adopted simplified modeling method has good accuracy in predicting the lateral displacements and inter-story drifts in the linear and nonlinear analysis. Furthermore, the simplified model has good accuracy in predicting the first modal shape and its corresponding period, while it has less accuracy in predicting the higher modal shapes and periods. Also, it was found that the simplified model underestimates the Max and Min story acceleration in comparison with the accurate model. The parametric study confirmed the proposed method's applicability on different configurations and topologies of tall buildings with an outrigger system. As a result, the simplified modeling method gives a deep understanding of the outrigger system behavior and its parameters. Therefore, it is an effective tool for modeling and analysis in the preliminary design stage. However, further improvements on the simplified modeling method should be conducted in future studies to increase the accuracy and quality of the obtained results and avoid its disadvantages.

On the Built-Environment Quality in Nearly Zero-Energy Renovated Schools: Assessment and Impact of Passive Strategies

Indoor Environmental Quality (IEQ) is a crucial issue in school buildings, because of the conditions that pupils and students are exposed to. From this assumption, potentialities of retrofit actions with Nearly Zero-Energy Building (NZEB) targets were analyzed in existing school buildings, focusing on the impact of such measures of IEQ. Numerical analyses in a transient regime for a typical school building were carried out to assess the impacts on the thermal comfort and Indoor Air Quality (IAQ). The study took into account several building configurations and three reference cities. The results showed severe overheating risks in retrofitted schools: the operative temperature increased by several degrees with respect to the existing configuration, leading to thermal discomfort for a relevant part of the observation period. Passive techniques, namely external solar protection devices and night ventilative cooling, were applied to assess their mitigation potential. Results showed that the combination of the two solutions restored the pre-retrofit performance. CO2 levels were found to be too high for naturally ventilated buildings, regardless of the building configuration; acceptable levels might be reached only with long opening times of windows, which are unrealistic for real building operation.

Inverse reinforcement learning to assess safety of a workplace under an active shooter incident

Active shooter incidents are posing an increasing threat to public safety. Given the majority of the past incidents took place in built environments (e.g., educational, commercial buildings), there is an urgent need for a method to assess the safety of buildings under an active shooter situation. This study aims to bridge this knowledge gap by developing a learning technique that can be used to model the behavior of the shooter and the trapped civilians under an active shooter incident. Understanding how the civilians respond to different simulated environments, a number of actions can be undertaken to bolster the safety measures of a given facility. This study provides a customized decision-making tool that adopts a tailored maximum entropy inverse reinforcement learning algorithm and utilizes some safety measurement metrics, such as the percentage of civilians who can hide/exit in/from the system, to assess a workplace’s safety under an active shooter incident. For instance, our results demonstrate how different building configurations (e.g., location and number of entrances/exits, hiding places) play a significant role in the safety of civilians under an active shooter situation. The results further demonstrate that the shooter’s prior shooting experiences, the type of firearm carried, and the timing of the incident are some of the important factors that may pose serious security concerns to the civilians under an active shooter incident.

Energy storage capacity configuration of building integrated photovoltaic‐phase change material system considering demand response

Energy storage capacity configuration of building integrated photovoltaic‐phase change material system considering demand response

Emissions and power demand in optimal energy retrofit scenarios of the Finnish building stock by 2050

Finland and the European Union aim to reduce CO2 emissions by 80–100 % before 2050. This requires drastic changes in all emissions-generating sectors. In the building sector, all new buildings are required to be nearly zero energy buildings. However, 79 % of buildings in Finland were built before 2000, meaning that they lack heat recovery and suffer from badly insulated facades.This study presents four large-scale building energy retrofit scenarios, showing the emission reduction potential in the whole Finnish building stock. Six basic building types with several age categories and heating systems were used to model the energy demand in the building stock. Retrofitted building configurations were chosen using simulation-based multi-objective optimisation and combined according to a novel building stock model.After large-scale building retrofits, the national district heating demand was reduced by 25–63 % compared to the business as usual development scenario. Despite a large increase in the number of heat pumps in the system, retrofits in buildings with direct electric heating can prevent the rise of national electricity consumption. CO2 emissions in the different scenarios were reduced by 50–75 % by 2050 using current emissions factors.

The nature of build changes

Build systems are an essential part of modern software projects. As software projects change continuously, it is crucial to understand how the build system changes because neglecting its maintenance can, at best, lead to expensive build breakage, or at worst, introduce user-reported defects due to incorrectly compiled, linked, packaged, or deployed official releases. Recent studies have investigated the (co-)evolution of build configurations and reasons for build breakage; however, the prior analysis focused on a coarse-grained outcome (i.e., either build changing or not). In this paper, we present BuildDiff, an approach to extract detailed build changes from Maven build files and classify them into 143 change types. In a manual evaluation of 400 build-changing commits, we show that BuildDiff can extract and classify build changes with average precision, recall, and f1-scores of 0.97, 0.98, and 0.97, respectively. We then present two studies using the build changes extracted from 144 open source Java projects to study the frequency and time of build changes. The results show that the top-10 most frequent change types account for 51% of the build changes. Among them, changes to version numbers and changes to dependencies of the projects occur most frequently. We also observe frequently co-occurring changes, such as changes to the source code management definitions, and corresponding changes to the dependency management system and the dependency declaration. Furthermore, our results show that build changes frequently occur around release days. In particular, critical changes, such as updates to plugin configuration parts and dependency insertions, are performed before a release day. The contributions of this paper lay in the foundation for future research, such as for analyzing the (co-)evolution of build files with other artifacts, improving effort estimation approaches by incorporating necessary modifications to the build system specification, or automatic repair approaches for configuration code. Furthermore, our detailed change information enables improvements of refactoring approaches for build configurations and improvements of prediction models to identify error-prone build files.

Estimation of wind pressure coefficients on multi-building configurations using data-driven approach

Wind load acting on a standalone structure is different from that acting on a similar structure which is surrounded by other structures in close proximity. The presence of other structures in the surrounding can change the wind flow regime around the principal structure and thus causing variation in wind loads compared to a standalone case. This variation on wind loads termed as interference effect depends on several factors like terrain category, geometry of the structure, orientation, wind incident angle, interfering distances etc., In the present study, a three building configuration is considered and the mean pressure coefficients on each face of principle building are determined in presence of two interfering buildings. Generally, wind loads on interfering buildings are determined from wind tunnel experiments. Computational fluid dynamic studies are being increasingly used to determine the wind loads recently. Whereas, wind tunnel tests are very expensive, the CFD simulation requires high computational cost and time. In this scenario, Artificial Neural Network (ANN) technique and Support Vector Regression (SVR) can be explored as alternative tools to study wind loads on structures. The present study uses these data-driven approaches to predict mean pressure coefficients on each face of principle building. Three typical arrangements of three building configuration viz. L shape, V shape and mirror of L shape arrangement are considered with varying interfering distances and wind incidence angles. Mean pressure coefficients (Cp mean) are predicted for 45 degrees wind incidence angle through ANN and SVR. Further, the critical faces of principal building, critical interfering distances and building arrangement which are more prone to wind loads are identified through this study. Among three types of building arrangements considered, a maximum of 3.9 times reduction in Cp mean values are noticed under Case B (V shape) building arrangement with 2.5B interfering distance. Effect of interfering distance and building arrangement on suction pressure on building faces has also been studied. Accordingly, Case C (mirror of L shape) building arrangement at a wind angle of 45° shows less suction pressure. Through this study, it was also observed that the increase of interfering distance may increase the suction pressure for all the cases of building configurations considered.

A CFD-Based Optimization of Building Configuration for Urban Ventilation Potential

In this paper, we present a performance-based approach to building configuration design to improve the urban ventilation potential at the conceptual design stage, and we demonstrate its application through a case study. The target performance optimized was the ventilation potential of a district, including a region of interest at a spatial scale of hundreds of meters. To estimate this performance, we used computational fluid dynamics (CFD), coupled with an evolutionary algorithm, to optimize the design alternatives to produce the building configuration most suitable for a given set of site conditions. Three calculation components must be assembled for a CFD-based design optimization: an optimizer, a geometry/mesh generator, and a CFD solver. To provide links between the calculation components, we utilized an in-house parametric design program. A case study was conducted to test the applicability of the proposed design method to identify the optimal solutions that minimize adverse effects on the ventilation potential of the surrounding area. For a configuration of buildings in a dense urban area, the proposed design method successfully improved the design alternatives. The results show that the urban ventilation potential in the case of the optimized building configuration is 16% greater than that of the initial building configuration.

Experimental and Numerical Studies on Setback Buildings Considering the SSI Effect under Seismic Response

From the previous studies it is observed that due to the effect of the earthquake, several irregular buildings failed vulnerably. Further the effect of sub soil conditions where these buildings have been founded also play an important role on the seismic response of these buildings. In the past, experimental studies on the seismic response of different setback building configurations have not been carried out. Therefore, in the present study the seismic behaviour of setback buildings considering Soil Structure Interaction (SSI) has been evaluated by conducting experimental and numerical investigations. Buildings with various setback configurations were considered and are designed as pile foundation supported structures. The irregularity index of these building configurations have been determined as per the existing codal provisions. These piles supported buildings representing the prototype structure have been scaled down according to geometric, kinematic and dynamic scaling laws. The scaled building models are subjected to vibrations beyond resonant frequencies using shake table facility. A comparison of the results has been made between experimental and numerical investigations. Based on the study it has been observed that storey displacements of building with regular configurations are higher in comparison with the setback buildings. It is also found that asymmetrical and symmetrical setback buildings having different irregularity indices as per IS:1893-2016 indicate nearly the same displacements at resonant frequencies. Doi: 10.28991/cej-2021-03091664 Full Text: PDF

Application of high-fidelity modelling approach to predict smoke and fire propagation in a nuclear fire scenario

Fire and smoke propagation from an electrical cabinet fire in a multi-compartment geometry was simulated using computational fluid dynamics (CFD) in this study. The URANS turbulence modeling approach, and variants of two-equation models available within the CFD code STAR-CCM + were tested for non-vented and vented conditions. Specifically, the ability of the turbulence models to predict the smoke and hot gas spread was analysed qualitatively. The ceiling jet and plume spilling phenomenon reported in literature was predicted in the progression of smoke propagation. It was observed that the ventilation created better mixing, enhanced the spreading of the stratified smoke layer and resulted in delayed progression of smoke propagation compared to the non-vented cases. A qualitative assessment of CFD predictions for temperature distribution was also undertaken using a slightly different geometry. It was found that the qualitative predictions obtained by the application of two-equation turbulence models for the temperature and smoke distribution were realistic and in-line with earlier studies using a similar building configuration. The findings from this study are expected to be beneficial in the assessment of existing two-equation turbulence models to predict smoke propagation in multi-compartment fires.

Space Syntax Guide to Optimize Shopping Mall

The shopping mall is a facility for profit-making with a complex spatial configuration that prioritizes the effectiveness in any aspects. The spatial configuration of a shopping mall needs more than a rule of thumb or a subjective judgment to optimize it. Many researchers have conducted studies of shopping mall spatial configuration by the theory and method of space syntax. But, the complexity of space syntax turns it hard to understand or apply in practical use. Due to the complexity of both shopping mall and space syntax, a guide is needed for practical directions to optimize shopping mall. This article review combines and synthesizes the findings of space syntax precedent studies. The scope of the study is on the building configuration scale (mesoscale). As the result, the optimization of a shopping mall can be measure by space syntax through measurement of connectivity, depth, integration, choice, and intelligibility. Each measurement has a different purpose. The most used measurement in shopping mall study is integration. The spatial configuration of the mall can be represented by the axial map, convex map, isovist map, VGA map, and agent-based in space syntax analyses. The most suitable map for shopping mall analysis is the VGA map because it shows the visual quality is vital in shopping mall design. There are several aspects of the shopping mall that can be adjusted or modified to optimize the shopping mall. Those aspects are pedestrian flows, horizontal complexity, vertical complexity, tenant type allocation, visual quality, retail placement, and anchor placement.

Seismic response of reinforced concrete wall buildings with nonlinear coupling slabs

Reinforced concrete (RC) structural walls are widely used in high-rise buildings as the lateral force resisting system because of their inherent economy, stiffness, and strength. The floor plan configuration of residential buildings in Chile consists mainly in assemblies of large longitudinal walls and shorter transverse walls coupled by floor slabs. The coupling effect of the slabs has affected the response and the observed damage of RC buildings in recent earthquakes. The main objective of this article is to assess the seismic response of a RC structural wall building with coupling slabs. Additionally, the effect of the amount of slab reinforcement on the seismic response of the building is evaluated. To achieve the proposed objectives, seven three-dimensional models of a case study building were developed using shell-type elements in DIANA. The first four models aim to evaluate the effect of using elastic slabs with reduced (i.e. cracked) moment of inertia. The last three models consider nonlinear behavior for both walls and slabs. The response of the building was estimated using nonlinear static analysis and the seismic performance is evaluated from the results of roof displacement and shear, moment, and axial forces of the walls. Additionally, the seismic performance is evaluated from the strain demands of concrete and steel in both walls and slabs. Relevant conclusions about the building behavior, slab demands, and failure mode are drawn.

Pengaruh Tata Bangunan dan Jalan Terhadap Aliran Udara Pada Kawasan Perkotaan

Designing configuration of buildings and streets in an urban area by maximizing air movement is an approach of the sustainable city. The existing buildings and streets of an urban area can affect the microclimate formed, including the airflow. The airflow can be used to create a comfortable city environment. Jalan Gajahmada is one of the economic strategic areas in Pontianak City which requires a comfortable condition to support activities there. The airflow that occurs in Gajahmada Street affects the conditions that occur now. This paper aims to provide an overview of airflow conditions on Gajahmada Street Area. The research method is through computer simulations using the Envi-Met simulation program. The data used local climate data and field data based on surveys. Through the analysis, it is known that the airflow is strongly influenced by the direction of the wind, the surface mass of the building and the ratio between the height of the building to the width of the streets that is formed from the distance between building masses (H / W).

Urban form study for wind potential development

Wind energy development is helpful for realizing a green city. This work concentrates on the study of estimating urban wind energy with consideration of urban morphology. Fourteen typical urban forms in Beijing city were selected and analyzed with nine relevant urban morphology parameters. Computational fluid dynamics numerical simulations were used to evaluate the wind energy potential of the urban forms. This work demonstrates that urban forms with higher plot ratio and mean aspect ratio usually have higher wind potential density by site area, an important indicator for neighborhood-scale wind potential development. Urban forms with higher average building height would have higher wind potential density by roof area, an important indicator for building-scale wind potential development. To promote wind potential over roofs, a layout of 45° of building configuration with inlet wind direction and building forms with round-angle corners are suggested. Local wind distribution is important for wind energy evaluation of individual buildings and wind energy distribution over different directions; however, it has a substantially lesser effect on the general wind potential comparison among urban forms with different urban characteristics.

Non‐linear mixed‐effects models for time series forecasting of smart meter demand

AbstractBuildings are typically equipped with smart meters to measure electricity demand at regular intervals. Smart meter data for a single building have many uses, such as forecasting and assessing overall building performance. However, when data are available from multiple buildings, there are additional applications that are rarely explored. For instance, we can explore how different building characteristics influence energy demand. If each building is treated as a random effect and building characteristics are handled as fixed effects, a mixed‐effects model can be used to estimate how characteristics affect energy usage. In this paper, we demonstrate that producing 1‐day‐ahead demand predictions for 123 commercial office buildings using mixed models can improve forecasting accuracy. We experiment with random intercept, random intercept and slope and non‐linear mixed models. The predictive performance of the mixed‐effects models are tested against naive, linear and non‐linear benchmark models fitted to each building separately. This research justifies using mixed models to improve forecasting accuracy and to quantify changes in energy consumption under different building configuration scenarios.

WITHDRAWN: Seismic analysis of G + 9 framed structures made of reinforced concrete resting on hill slopes

This work is an attempt to understand the behavior of structures on hill slopes. Due to unavailability of plain lands, the construction of buildings is started on sloping grounds. A brief review of the literature is available on the geometrical configuration of structures resting on sloping ground, setback and step-back structures, and torsion coupling of asymmetric structures. A 9 storey structure configured for two different slopes and two regular structures for flat ground with 3 and 9 storeys were taken in consideration for analytical investigation. Various configured building structures resting on hill slopes were studied using a parametric study to avoid torsion and stiffness irregularities by placing shear walls at different locations and varying the height of ground supported columns. The results obtained from the analysis shown good agreement with the results obtained for building structures resting on flat grounds. From the results, it is identified that failure of structural elements can be avoided by placing shear walls and varying height of ground-level columns. It was observed that Step-back Set-back building configuration is suitable for building structures on hill slopes.

Critical indicators of sustainability for mixed-use buildings in Lagos, Nigeria

Sustainable cities’ growth and developmental pattern relies on design and planning that meets its inhabitants’ needs. Seemingly, in these cities mixed-use buildings exists as skyline dots of vertical, horizontal and as shared ‘premises’ building dimensions. Essentially, mixed-use buildings are gradually replacing urban neighbourhood zooning design and building configurations particularly along major streets in the built environment. Significantly, Lagos state government in Nigeria has invested in the development of Model City Plans (MCPs) as district and neighbourhood regenerating process of which mixed-use building concept is an essential part of the scheme. Hence the need to develop a sustainability guide for mixed-use buildings leveraged on the experience of stakeholders particularly the inhabitants of these environments. The study therefore aims to establish critical indicators applicable for a sustainable mixed-use building development in Lagos, Nigeria. The study adopted questionnaire survey in soliciting for data which was thereafter analysed using inferential statistics. In this regard 341 respondents inhabiting mixed-use buildings were surveyed after selection through random sampling. Thereafter a trail of inferential statistics with empirical evidences evolved relating the critical indicators necessary for sustainability of mixed-use building as inspired by the users. The outcome established six (6) domains termed critical indicators because of the significant association of their factors for mixed-use building sustainability in Lagos, Nigeria. Notably, these developed domains adequately considered the pillars of sustainability relevant to mixed-use unlike existing guides that are mostly mono-dimension. Hence it is expected that the proposed indicators promote sustainable mixed-use, enhance sustainable city growth, creates resilient and self-sustaining cities. • Lagos Model City Plans desire mixed-use concept in district & neighbourhood renewal projects. • Contextual mixed-use building indicators are critical for sustainable building development. • Resilient & self-sustaining cities rely on mixed-use indicators rich in local content.

Optimizing Civilian Response Strategy Under an Active Shooting Incident

Active shooting (AS) violence poses a serious threat to public safety. Most importantly, this number is increasing at an alarming rate over the last few years. Unfortunately, the knowledge base on attack detection and civilian response strategy under an AS incident are very limited. Such a lack of understanding hinders the development of effective training modules, response, and mitigation strategies (for both civilians and law enforcement officers) for an event that is highly unpredictable and unfolds quickly (typically in less than 5 min). To fill this gap in the literature, this article proposes an innovative mathematical model which captures several important features (e.g., capacity of the facility and individual choices, heterogeneity of individual behavioral and choice sets, restriction on choice sets depending on the location of the shooter and facility orientation, and many others) which are essential for appropriately characterizing and analyzing the response strategy for civilians under an AS exposed environment. We demonstrate the applicability of the proposed model by implementing the effectiveness of the RUN.HIDE.FIGHT. program in an academic environment. Results indicate that cognitive delay, the initial distribution of the civilians, and building configurations (e.g., location and number of entrances/exits) play a significant role in the safety of civilians under an AS incident.