skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Exploring the impact of vertically separated flows on wind loads of multi-level structures
The complex dynamics of vertically separated flows pose a significant challenge when it comes to assessing the wind loads on multi-level structures, demanding a nuanced understanding of the intricate interplay between atmospheric conditions and architectural designs. Previous studies and wind loading standards provide insufficient guidance for designing wind pressures on multi-level buildings. The behavior of wind around perpendicularly attached surfaces is not quite similar to that of individual flat roofs or walls. When a body is composed of several surfaces with right or oblique angles, the separated flow from surfaces and their interactions will cause complex flow patterns around each surface. A wind tunnel experimental study was carried out on bluff bodies with attached flat plates and other adjacent bluff bodies with different heights to examine the wind-induced pressures on such complex shapes. Mean and peak pressure coefficients were measured to determine the flow interaction patterns and location of localized peak pressures. The results were compared to the Tokyo Polytechnic University Aerodynamic Database of isolated low-rise buildings without eaves. The research findings indicated that there was a noteworthy disparity between the minimum and maximum values and locations of peak pressures on both the wall and roof surfaces of the models used in this study, as compared to the results obtained by the Tokyo Polytechnic University. Moreover, the study conceivably pointed to the difference between the peak negative and positive pressure coefficient locations with the ASCE 7-22 wind loading zones. The peak suction zones were affected by the combined flows at perpendicular faces, and as a result, different wind load zones were obtained dissimilar to those introduced by ASCE 7-22. Wind loading standards may need to be modified to account for the wind pressures on complex building structures with an emphasis on the location of the peak negative pressure zones.  more » « less
Award ID(s):
1841503
PAR ID:
10486061
Author(s) / Creator(s):
;
Publisher / Repository:
Frontiers
Date Published:
Journal Name:
Frontiers in Physics
Volume:
11
ISSN:
2296-424X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. This dataset includes files from an extensive wind tunnel study of stepped-roof buildings conducted at the Wall of Wind facility at Florida International University. The aim of the study was to clarify the key factors that affect aerodynamic forces on complex architectural shapes. While ASCE7-22 offers a guideline for wind loads on building components and roofs, it falls short of providing the detailed data needed by engineers to calculate wind loads on the surfaces of stepped-roof buildings. This study fills that gap. The main subject under investigation was the impact of wind loads on different building geometries such as stepped roofs, U-shaped buildings, podium structures, and low-rise buildings with carport extensions. This involved a detailed examination of how various structural features influenced wind pressure distribution, with a specific emphasis on understanding the behavior of wind forces on these models. The outcomes include a series of detailed findings on wind pressure coefficients for each building model. These results offer insights into the wind load characteristics for different architectural forms, contributing to a better understanding of structural behavior under wind forces. The study findings will furnish additional data to enable engineers and scholars to more accurately assess and comprehend wind loads on buildings with multi-level roofs. The dataset includes diagrams of each model’s geometry and wind pressure data. The data highlighted key areas where wind pressures were most significant and how different building features either mitigated or exacerbated these pressures. The data gathered from this study can be reused in multiple ways. It can serve as a reference for designing wind-resilient buildings, particularly in regions susceptible to strong winds or hurricanes. The empirical data can also aid in validating and refining computational models for predicting wind loads on buildings. Additionally, it can be used in academic research for further exploration into wind engineering, urban planning, and architectural design, potentially leading to innovations in building safety standards and construction practices. 
    more » « less
  2. Tsunami overland flow induces hydrodynamic loads on coastal structures and may transport various objects located within the inundation zone, which could become debris and exacerbate hydrodynamic loading. In the process of adopting “the first national, consensus-based standard for tsunami resilience” (Chock, 2016) in the form of ASCE 7-16 Chapter 6: Tsunami Loads and Effects, emphasis was placed on evaluating debris transport and impact forces. This is evidenced by the robust body of literature regarding physical model experiments of these processes and thorough design procedures for both load considerations in current structural engineering standards (ASCE, 2022). Debris damming forces, resultant of debris being transported and accumulating against structures, are less thoroughly studied, having only recently begun to transition from steady flow experiments to transient flow conditions representative of coastal inundation events. A recent pair of experiments bridges this gap, comparing debris damming via steady-state, subcritical flow conditions to that caused by a dam-break style hydraulic bore (Stolle et al., 2018). That paper aimed to study debris dam formation, stability, and loading as well as runup of the flow onto idealized structural columns. Another study varied debris quantity, orientation, and arrangement to determine the effect had on damming and impact loads (Shekhar et al., 2020), however neither compared findings to current standards. The experimental work presented herein represents initial findings of a multi-year experimental campaign to better understand the mechanisms that lead to debris damming and increased structural loading. This work builds upon previous studies by using larger scale debris elements, more numerous debris fields, and more trials to better model such a stochastic process as debris damming. Three different incident wave conditions also led to varied hydrodynamics at the column specimen. In later phases, this campaign will also investigate the debris damming consequences of heterogeneous debris, which more accurately represent highly variable debris fields observed in post-event site surveys (Nistor et al., 2017). This paper aims to compare experimental debris dam loading parameters to those in the current ASCE 7-22 standard (ASCE, 2022). Namely, evaluating conservatism of ASCE 7-22 design values for: overall drag force on buildings, minimum closure ratios used in load determination, and empirical rectilinear structure drag coefficients during both debris accumulation and quasi-steady debris damming phases. 
    more » « less
  3. Boundary Layer Wind Tunnel (BLWT) facilities are commonly used for assessing wind loads on structures. Although BLWT facilities routinely match 1st and 2nd-order wind profile models, evidence suggests that turbulence in the roughness sublayer and the inertial sublayer exhibit non-Gaussian higher-order properties. These non-Gaussian properties can influence peak wind pressures, which govern certain structural limit states and play an important role in design. In the first part of this project, Machine learning (ML) methods are employed to identify relationships between roughness element configurations and higher-order statistical properties of the wind field. A semi-automated framework with an active learning portion and a wind tunnel experimental procedure is developed. The learning framework adaptively selects roughness profiles and launches new experiments to identify differing profiles with second-order equivalent flow as quantified by turbulence intensity. The premise is that second-order equivalent wind fields can differ in higher-order properties and therefore extreme value derived peak loads may differ. Over the course of this project, the turbulence profiles from hundreds of different Terraformer roughness element configurations were collected, providing a very rich dataset of boundary layer flow as a function of upwind fetch. Experiment 1 provides the metadata to describe and interpret measured wind profiles at the UFBLWT for a data set collected for the Benchmark experiments and 3 different phases: 1) Sinusoidal waves experiments, 2) Shape study experiments and, 3) Random field experiments. Experiment 2 of this dataset presents the results of experiments conducted in the UFBLWT, with a focus on measuring turbulence characteristics and pressure coefficients on a bluff body under varying terrain roughness configurations. The dataset provides valuable insights into the influence of upwind fetch and surface roughness on wind-induced forces, contributing to improved modeling and prediction of wind loads on structures. Based on the Terraformer configurations in experiment 1, select configurations (Benchmark and Phase 1 Terraformer configurations only) were chosen for bluff body experiments, along with additional approach turbulence measurements at a lateral location to the model. This dataset includes three key components for Benchmark and Phase 1 Terraformer configurations: reference wind velocity (uRef), lateral approach flow profiles (LatFlow), and pressure coefficients (Cpdata) on the bluff body. 
    more » « less
  4. Investigations on simulated near-surface atmospheric boundary layer (ABL) in an open-jet facility are carried out by conducting experimental tests on small-scale models of low-rise buildings. The objectives of the current study are: (1) to determine the optimal location of test buildings from the exit of the open-jet facility, and (2) to investigate the scale effect on the aerodynamic pressure characteristics. Based on the results, the newly built open-jet facility is well capable of producing mean wind speed and turbulence profiles representing open-terrain conditions. The results show that the proximity of the test model to the open-jet governs the length of the separation bubble as well as the peak roof pressures. However, test models placed at a horizontal distance of 2.5H (H is height of the wind field) from the exit of the open-jet, with a width that is half the width of the wind field and a length of 1H, have consistent mean and peak pressure coefficients when compared with available results from wind tunnel testing. In addition, testing models with as large as 16% blockage ratio is feasible within the open-jet facility. This reveals the importance of open-jet facilities as a robust tool to alleviate the scale restrictions involved in physical investigations of flow pattern around civil engineering structures. The results and findings of this study are useful for putting forward recommendations and guidelines for testing protocols at open-jet facilities, eventually helping the progress of enhanced standard provisions on the design of low-rise buildings for wind. 
    more » « less
  5. Abstract. Research often neglects historic and ageing infrastructure when investigating the impact of extreme wind loading and structural strengthening. This is exemplified by the ASCE 7-22 standard in the US that prescribes design loads for tornado hazard, which currently does not apply to Risk Categories (RC) 1 and 2, comprising a significant proportion of historic structures. After a disaster, analyzing these structures numerically can be difficult due to their complex geometries, use of multiple construction materials, and alterations to the original structure. This study aimed to digitally document and evaluate the damage caused by the Midwest Tornado in Kentucky in December 2021, specifically focusing on the historic downtown of Mayfield, KY. Building data was gathered using various devices, such as Unmanned Aerial Vehicle’s, LiDARs, and cameras, and converted into finite element meshes using the open-source software Cloud2FEM. Multiple meshes for the historic post office building in Mayfield, KY, was generated using varied rules within Cloud2FEM. These meshes were then simulated using Abaqus to qualitatively assess the stress concentrations observed under tornadic loading calculated using the ASCE7-22. 
    more » « less