6th American Association for Wind Engineering Workshop (online) Clemson University, Clemson, SC, USA

May 12-14, 2021

* Manuel Matus

Investigation of irregular-shaped buildings and their pressure distribution

Manuel Matus a*, Ioannis Zisis b

a Florida International University, Miami, Florida, USA, mmatu016@fiu.edu b Florida International University, Miami, Florida, USA, izisis@fiu.edu

ABSTRACT:

Wind related damages on low-rise residential buildings have caused billions of dollars in losses. Building code

provisions, that have been developed to mitigate such impact, were predominately based on testing models of regular

plans. This study aims at evaluating the wind-induced loads on buildings with non-rectangular shapes. Six models

with irregular shaped plans were tested at the Wall of Wind Experimental Facility at Florida International University.

Preliminary results showed that separation zones are more complex than those observed in a regular shaped building

and result in higher local and overall peak pressures. Preliminary area averaging curves have shown that current wind

standards might underestimate the actual pressures building undergo. Additional testing is ongoing to better

understand the effect of building shape in the local and overall pressure distribution.

Keywords: wind load, low-rise building, irregular-shaped

1. INTRODUCTION

Extreme wind events have caused billions of dollars in losses in the low-rise residential building

sector and are expected to increase to 39 billion dollars by 2075 (USDOC 2010, CBO 2019).

Current wind standards provide guidance for the safe design of residential structures to reduce

potential damages due to wind induced loads (ASCE 7-16). These wind load provisions have been

developed based on results obtained from wind tunnel testing on regular shaped structures in the

late 1970’s (Akins et al., 1977, Davenport et al., 1977 and Stathopoulos 1979) and have been

enhanced and improved over the next few decades through several wind tunnel studies. With

advancements on technology and construction techniques, the shapes of structures have become

considerably more complicated than just rectangular and squared shapes. As a result, several wind-

tunnel and numerical investigations have been carried out to better understand the effects of

extreme wind events on such structures; however, most have focused on mid- to high-rise

structures (Shuai et al., 2019; Stathopoulos et al., 1993; Mashalkar et al., 2015; Gomez et al., 2005;

Young et al., 2016; Souvik et al., 2014; Yi et al., 2016, 2017, 2020; Don-Xue et al., 2017).

Although current building codes provides guidance on how to account for building plan

irregularities, there are no guidelines on how to account for the aerodynamic effects caused by

complex shapes. Some investigations have concluded that there has been a lack of attention on the

investigation on low-rise residential buildings and that the current building code wind provisions

underestimates the actual wind loads on such structures (Stathopoulos 1984 and Jin et al., 2020).

2. METHODOLOGY AND TEST PLAN

14

6th American Association for Wind Engineering Workshop (online) Clemson University, Clemson, SC, USA

May 12-14, 2021

To obtain the most common irregular shapes of low-rise residential structures, several satellite

images of South Florida residential areas were obtained and visually analysed. From these images,

T, L and C were observed to be the most common shapes. Having identified the shapes, dimensions

were obtained and a total of seven models were designed and constructed (two T-, L- and C- and

one Rectangular-shaped model) out of 3/8” plexiglass, at a 1:50 scale and instrumented with

approximately 350 pressure taps each. The models were tested at the Wall of Wind (WOW)

Experimental Facility at Florida International University in Miami, Florida, with an open terrain

exposure. The tests were carried out at 30 mph with a 15degree wind direction step.

3. RESULTS

From the experimental data obtained, pressure coefficients (𝐶𝑝,𝑚𝑒𝑎𝑛 𝑎𝑛𝑑 𝐶𝑝,3𝑠) were acquired and

some of the contour plots are presented here. The rectangular model served as the base model and

was compared against NIST and TPU results with satisfactory agreement (Ho et al., 2005, Tamura

2012). Representative cases of the 𝐶𝑝,𝑚𝑒𝑎𝑛 for a T- and an L-shaped models at 0 degrees is

presented in Figure 1 and Figure 2. The pressure distributions reveal that these structures develop

more separation zones than a regular shaped structure due to the increased number of sharp

edges/corners, thus experiencing more local and overall peaks. Area averaging calculations, for

roof and walls, were also generated with peak pressure coefficients for all examined wind

directions. These graphs provide information to estimate the critical pressures that components

and cladding (C&C) elements can experience based on their different surface areas. They also

provide the means to compare results to current building code wind load provisions envelope

curves. This preliminary exercise showed that current recommendations may underestimate the

wind-induced pressures on more complex building shapes.

Figure 1. Mean Cps model T1

Figure 2. Mean Cps model L1

4. CONCLUSIONS

Low-rise residential structures are highly susceptible to wind-induced damage. Substantial

economical loses indicate the urgent need to enhance the survivability and resilience of residential

construction. Wind load provisions were developed based on regular-shaped isolated-models

tested in wind tunnel over the past 40 years. Today’s built environment has evolved in structures

having complex shapes making the design process of such structures somewhat intuitive. The work

presented in this paper provides preliminary findings obtained from testing seven irregular shaped

models at the WOW Experimental Facility. Results show that buildings having irregular plans

15

6th American Association for Wind Engineering Workshop (online) Clemson University, Clemson, SC, USA

May 12-14, 2021

have more edges where flow separation occurs, areas which are known to develop high suction

zones thus resulting in high local and overall peak pressure coefficients. Area averaging curves

developed from the tested cases, show that ASCE 7-16 might underestimate the loads that

buildings with irregular shapes undergo. A comprehensive investigation is needed to fully

understand the effect of irregular plans in the local and overall pressure distribution as well as the

aerodynamics of such structures to mitigate wind induced damages.

5. REFERENCES C. B. O. Congress of the United States, "Potential Increase in Hurricane Damage in the United States: Implications

for the Federal Budget," June 2016.

Dong-Xue Zhao, Bao-Jie He. 2017. Effects of architectural shapes on surface wind pressure distribution: Case studies

of oval-shaped tall buildings. Journal of Building Engineering. 2017. 12 (2017) 219-228.

DOI:http://dx.doi.org/10.1016/j.jobe.2017.06.009

Gomes M. G., Rodrigues A. M., and Mendes P. 2005. Experimental and numerical study of wind pressures on

irregular-plan shapes. Journal of Wind Engineering and Industrial Aerodynamics.

Ho, T. C. E., D. Surry, D. Morrish, and G. A. Kopp. 2005. The UWO contribution to the NIST aerodynamic

database for wind loads on low buildings. Part 1: Archiving format and basic aerodynamic data. Journal of Wind

Engineering and Industrial Aerodynamics. 93 (1): 1–30. https://doi.org/10.1016/j.jweia .2004.07.006.

Jin Wang, Gregory A. Kopp. 2021. Comparisons of aerodynamic data with the main wind force-resisting system

provisions of ASCE 7-16. I. Low-rise buildings. Journal of Structural Engineering. DOI:10.1061/(ASCE)ST.1943-

541X.0002925.

Mashalkar B. S., Patil G. R., and Jadhav A. S. 2015. Effect of plan shapes on the response of buildings subjected to

wind vibrations. IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE).

Shuai Shao, Tuji Tian, Qingshan Yang, Ted Stathopoulos. 2019. Wind-induced cladding and structural loads on low-

rise buildings with 4:12-sloped hip roofs. Journal of Wind Engineering and Industrial Aerodynamics, Beijing China.

Souvik C., Sujit K. D., and Ashok K. A. 2012. Wind load on irregular plan shaped tall building - a case study.

Stathopoulos T. 1984. Wind loads on low0rise buildings: a review of the state of the art. Engineering Structures. Vol.

6. Issue 2. 1 1984- 119-135.

Stathopoulos, Ted and Zhou, Y. 1993. Computation of wind pressures on L-shaped buildings. Journal of Engineering

Mechanics.

Tamura, Y. (2012), Aerodynamic Database for Low-Rise Buildings, Global Center of Excellence Program, Tokyo

Polytechnic University, Database.

United States Department of Commerce (USDOC). 2010. Coastline Population Trends in the United States: 1960-

2008.

Yi Li, Q.S. Li, Fubin Chen. 2017. Wind tunnel study of wind-induced torques on L-shaped tall buildings. Journal of

Wind Engineering and Industrial Aerodynamics. 167 (2017) 41-50.

DOI:http://dx.doi.org/10.1016/j.jweia.2017.04.013.

Yi Li, Qiu-Sheng Li. 2016. Wind-induced response based optimal design of irregular shaped tall buildings. Journal of

Wind Engineering and Industrial Aerodynamics. 155 (2016) 1978-207.

DOI:http://dx.doi.org/10.1016/j.jweia.2016.06.001.

Yi Li, Ru-Biao Duan, QIU-Sheng Li, Yong-Gui Li, Chao Li. 2020. Research on the characteristics of wind pressures

on L-shaped tall buildings. Advances in Structural Engineering. DOI:10.1177/1369433220906934.

16

6th American Association for Wind Engineering Workshop (online) Clemson University, Clemson, SC, USA

May 12-14, 2021

Young Tae Lee, Soo Li Boo, Hee Chang Lim, kunio Misutani. 2016. Pressure distribution on rectangular buildings

with changes in aspect ratio and wind direction. Wind and Structures. Vol. 23, No. 5 (2016) 465-483.

DOI:http://dx.doi.org/10.12989/was.2016.23.5.465.

17