Facade Wind Loading

Modeling Facade Performance Subject to Wind Loads in Urban Environments

Overview

Authors


Keywords


Abstract

Wind induced pressure is a major design consideration for building facades. However, the effects of facade geometry and urban terrain on wind loading are often difficult to quantify without costly and time-consuming wind tunnel testing. Accurate 3-dimensional data, covering most major cities, is becoming increasingly accessible, and such models are ideal to support numerical modeling of environmental effects on the built environment, especially if such modeling attempts to capture the geometric effects of the cityscape.

This paper describes a new methodology to assess the effects of wind loads on the structural strength of glass using transient, geometrically non-linear analyses and improved glass failure prediction models. A description is provided for both the calculation of wind-induced facade loads, and the development and employment of a finite element (FE) solver to model facade performance.

A Reynolds Averaged Navier-Stokes (RANS) solver for incompressible turbulent flow with the standard k-ε turbulence model is used to calculate air flow velocities and pressure loads for the model. The RANS approach predicts the mean flow field in the domain and can be applied to achieve analysis results in a computationally cost-effective manner. Facade response is calculated using a FE solver that represents the structural mullions as Timoshenko-type beam elements while glass lites, interlayers, and IGU spacers are modeled with reduced-integration shell elements. Constant stress solid elements are used to represent the IGU air gaps and structural silicone. Using this mixed element approach, a design-level fidelity is achievable, facilitated through the use of user-defined constitutive models for glass, PVB, and silicone. Glass material behavior is characterized with a material model with an embedded flaw-based probabilistic failure criterion consistent with ASTM E1300 Standard Practice for Determining Load Resistance of Glass in Buildings. In addition to glass material behavior, hyper-elastic material models that incorporate dynamic strength increases associated with both strain and strain-rate are also used to characterize the material behavior of PVB and silicone.

Introduction

The design of buildings and structures requires an accurate assessment of wind loads on the structural system and cladding elements to ensure efficient and reliable design. Loads obtained from building

Members Only

Background

The wind speeds used to determine loads in this study are based on the “consistent risk” concept used in ASCE 7, in which “design loads,” when multiplied by a load

Members Only

Model Development

Accurate 3-dimensional data, covering most major cities, is becoming increasingly accessible and these models are ideal for numerical modeling, especially if such modeling attempts to capture the geometric effects of

Members Only

Wind Load Calculation

For smaller domains (e.g., single buildings), and internal flow problems PEC leverages a large eddy simulation (LES) approach. However, for wind calculations within urban cityscape environments a steady-state solver for

Members Only

High-Fiedlity Glazing Design

Leveraging the modeling and analysis capabilities of the finite element code LS-DYNA, PEC engineers have developed an approach for evaluating curtain wall performance during dynamic loading events, such as wind

Members Only

Conclusion and Future Work

The potential for finding optimized building solutions is unfolding through enormous development in computational design tools. CFD software, as detailed herein, enables the assessment of the wind loads on complex

Members Only

Rights and Permissions

American Society of Civil Engineers (ASCE) . 2016. "Minimum Design Loads for Buildings and Other Structures (ASCE 7-16)."

ASTM. 2016. E1300-16, Standard Practice for Determining Load Resistance of Glass in Buildings. West Conshohocken, PA: ASTM International.

Marchand, K., Davis, C., Sammarco, E., and Bui, J. 2017. "Extending Glass Facade Performance Predictions for Natural and Man-made Hazards Using Accesible High-Fidelity Formulations." 39th IABSE Symposium. Vancouver, Canada.