Performance-based Wind Research Articles

Performance-Based Wind Design of Tall Buildings Considering Corner Modification and Inelastic Behavior

Performance-Based Wind Design of Tall Buildings Considering Corner Modification and Inelastic Behavior

Potential for mitigating hurricane wind impact on informally-constructed homes in Puerto Rico under current and future climate scenarios

This study investigates the resilience of informally-constructed light-frame timber houses in Puerto Rico, a region where households with limited resources face significant risks from climate hazards, notably hurricanes. This study conducts a component-based, performance-based wind engineering assessment of informally-constructed house typologies, defined based on extensive fieldwork, under both existing and projected future climate conditions. Key findings highlight the effectiveness of certain mitigation strategies, such as reinforcing roof-to-wall connections, in significantly reducing the probability of failure. Fully-mitigated cases, which involve applying mitigation measures to the roof envelope, roof-to-wall connections, and shear walls, exhibited annual probabilities of failure that are much closer to, but do not necessarily meet, the threshold targeted by American building standards (i.e., ASCE 7). The results also show a dramatic increase in probability of failure of these houses projected by the adopted climate change model scenarios, driven by the increased frequency and intensity of hurricanes in Puerto Rico. Results from feedback from those working in the informal construction sector also identify challenges hindering the effective implementation of mitigation measures in Puerto Rican communities, including a lack of knowledge about how to implement the mitigation strategies and barriers related to real and perceived costs. Taken together these results underscore the urgent need for changes in building practices and revising building standards and suggesting potentially feasible mitigation strategies to improve those practices.

Performance-based wind engineering for roof cladding based on vulnerability analysis of roof plate unit

In response to frequent wind damage accidents in roof cladding, a performance-based wind engineering framework for roof cladding is proposed, taking the roof plate unit as the research object. In the uncertain analysis part, extreme wind pressures in each zone of the roof are evaluated using the independent storm method. In the vulnerability analysis part, a large number of numerical simulations are carried out based on Latin hypercube sampling to obtain the probability vulnerability curves of various types of roof plate units through regression fitting. In the loss analysis part, a total life cycle cost model of the roof cladding is established considering initial cost and wind disaster losses. In the performance target part, wind load levels and performance levels are divided based on the extreme wind pressure in each zone of roof under various return periods and the wind uplift failure process of roof plates respectively. Combined with wind load levels and performance levels, performance targets that can be selected by owners are proposed. The application of performance-based wind engineering is introduced using a flat roof as an example, which shows that the probability of reaching insignificant, moderate damage, and moderate damage under recurrence periods of 10, 50, and 100 years for a certain type of roof plate unit is 89 %, 91 %, and 72 %, respectively, which meets the owner's performance objectives and can be applied to guide the wind-resistant design of the cladding of the flat roof. Compared with the complexity of existing performance-based wind engineering, the performance-based wind engineering proposed in this manuscript can coordinate with the traditional wind-resistant design method of roof cladding, and can ensure the economy of design results.

Directional alongwind and crosswind effects on the performance of a 15-storey steel braced frame building in seismic environment

The effect of crosswind loads on buildings has been studied since the 1980s, but only a few researchers reported on the nonlinear response of tall buildings under ultimate crosswind loads. Performance-based wind design procedures provide a structurally efficient and economical alternative to prescriptive code based design, however their establishment necessitates further research in the following areas: i) development of a straightforward procedure for the derivation of reliable wind time-history loadings from wind tunnel data; ii) assessment of the dynamic behavior of tall buildings excited by wind in the full range of response: linear-nonlinear-near collapse; and iii) quantification of the effect of directionality on building performance in the full range of response. Herein, local aerodynamic data are used to produce reliable estimations of the directional alongwind and crosswind time-history loadings for a 15-storey steel braced frame hospital building, in Montreal, Canada. The case study is designed to withstand the code-based wind and earthquake loads, as independent load combination cases. Then, advanced finite element models are employed to assess the effect of directional alongwind and crosswind loads on the building performance under increasing levels of input wind motion. Ten excitation angles from 0° to 90° are considered. Incremental dynamic analysis is employed to assess the building performance under recurring winds, including the wind directionality effect. To monitor fatigue failure, the rainflow counting method is used to approximate the number and amplitude of loading cycles exhibited by ductile brace members of the lateral force resisting system.

Global vibration control of offshore wind turbines with a flexible monopile foundation using a pendulum-tuned mass damper: Risk mitigation and performance incrementation

This study investigates an optimized design approach for a passive-adaptive pendulum-tuned mass damper (PTMD). The PTMD is used to mitigate structural vibrations in offshore wind turbines (OWTs) with flexible monopile foundations considering Pile-Soil Interaction (PSI). The model OWT is based on the 5-MW design proposed by the National Renewable Energy Laboratory (NREL). The PSI incorporates a pile that is modeled as beam–column elements supported by nonlinear springs and accounts for lateral loads (p-y curves) and axial loads (t-z and Q-z curves) at nodal points. Wind and wave spectra estimation, as well as hydrodynamic and aerodynamic load analysis, are performed using a bespoke MATLAB® program operated in conjunction with an ANSYS® 3-D finite element global model. The resultant peak response at the OWT hub was evaluated through power spectral density (PSD) analysis. Optimal design choices for PTMD parameters are obtained via parametric analysis, which assesses the dynamic response in the along and across directions at the hub and stress at the tower base. A systematic representation considers the uncertainties stemming from the geometric and mechanical properties of the tower, environmental loads, and rotating blade dynamics. To address these uncertainties, a Monte Carlo simulation is employed to assess the structural risk via the Performance-Based Wind Engineering (PBWE) framework. Consequently, the probabilistic evaluation of structural response, foundation stresses, and power production assists in the optimal design process of PTMDs that mitigate the global structural vibrations of OWTs.

Performance evaluation of high-rise buildings using database-assisted design approach

In recent years, performance-based design (PBD) has gained attention and is sought to be the benchmark approach in the field of wind engineering. While the concept of performance-based design is well-accepted in earthquake engineering, it is yet to be embraced for the design of buildings to resist severe wind loads. This paper introduces a framework for the performance-based wind design (PBWD) of tall steel buildings using a time domain analysis that keeps the process of wind effects and the structural design process integrated, transparent, and fully auditable. From the perspective of PBWD, the main objective is to achieve a desirable performance level for a given hazard level, i.e., mean recurrence interval of extreme wind. The wind effects are directly related to the mean annual return of wind through a well-accepted simulation approach. A 180 m tall standard CAARC building is used for the case study to illustrate the proposed methodology. The wind load time histories are determined using the pressure tap data on exterior faces of the building measured in the wind tunnel. With the calculated wind loads, nonlinear dynamic analysis is conducted with various wind directions and mean wind speeds based on database-assisted design (DAD) approach. The key performance measures such as demand-to-capacity indices, inter-story drift, damage deformation index, and floor accelerations are calculated as a function of wind directions and mean wind speed. The obtained responses are used in conjunction with a local wind climatological database to determine the extreme wind effects for any specific mean recurrence interval. The performance of the steel building is evaluated for three performance criteria, including occupant comfort, operational, and continuous occupancy. The conducted performance assessment reveals that building fails to satisfy the serviceability requirement of drifts. However, the building satisfies the requirements for the occupant comfort and operational performance levels for strength design, while it also satisfies the continuous occupancy, limited interruption in Risk category II. The result reveals that the proposed framework provides realistic assessment of performance of the building incorporating the wind directionality and return period of the wind speeds.

Performance-based wind engineering assessment of a telecommunication mast utilizing Bayesian extreme wind velocity model

A promising design concept, the performance-based wind engineering methodology is adopted, implementing a finite element model (FEM) to analyse the structural behaviour of a telecommunication steel lattice mast. The integration of site-specific wind loading models into the standardized FEM-based design can be a powerful tool for design engineers. The tower being investigated, located in Central Hungary, is equipped with sensors to measure wind velocity and strains in chord members. The stochastic modelling of the extreme wind velocity, i.e., the basic wind velocity is assessed using the peak-over-threshold approach with an automated threshold selection method. To enhance the accuracy of the analysis, Bayesian inference is employed, combining the information from a relatively short duration of measurements collected at the tower site with a more extensive dataset from measurement locations across the country. Numerical model of the telecommunication mast subjected to wind loading is developed in a general-purpose finite element software. The probabilistic design system module is applied for performing probabilistic calculations of both serviceability criterion and load-bearing capacity of the structure using Monte Carlo simulation with Latin hypercube method. Numerical results are compared and validated with measurement data. The accuracy of wind load assessment is examined in this study, considering both the standardized design method according to EN 1993-3-1 and wind tunnel testing. The main objective is to demonstrate the potential of integrating the Performance-based Wind Design framework with a monitoring system and a finite element model, highlighting their combined benefits.

Nonlinear Behavior Study of Reinforced Concrete Coupling Beams Subjected to the Effect of Wind Loading

Reinforced concrete shear walls connected by coupling beams are considered an efficient structural system for tall buildings subjected to lateral loads. For seismic design of such buildings, performance-based design has been commonly used in regions with strong earthquakes for its ability to achieve economical and safe design, however the use of performance-based wind design (PBWD), which permits nonlinear response of ductile elements at specific locations under wind loads is still hindered due to the lack of information regarding the performance of these elements. In addition to that, there is still a need for developing an analytical model that can represent nonlinear behavior of these elements when subjected to wind loads. Therefore, in this study two analytical models using two different methods to consider bond slip effect (Bond SP01 (BS) model and steel modification factor (SMF) model) were developed and implemented in OpenSees software and validated with a tested specimen of reinforced concrete coupling beam subjected to a simulated windstorm loading protocol. Then, a parametric study was conducted using the SMF model to investigate the effect of axial restraint, and modification of the ductility demand. Results showed that both of the models showed good agreement with the experiment, however results of the SMF model were more accurate. As for the parametric study, it was concluded that with axial restraint, the beam behavior was dominated by shear, and a slight increase of strength was observed. At ductility demand of 1.8 θ y , the beam performed well with no significant damage and minor residual rotations.

Reliability of inelastic wind excited structures by dynamic shakedown and adaptive fast nonlinear analysis (AFNA)

The ever-growing interest in performance-based wind engineering has created a need for assessment frameworks that can efficiently deal with inelasticity. The computationally efficient strain-driven dynamic shakedown approach has provided a solution that is not only capable of identifying failure mechanisms that are potentially critical during extreme winds, e.g., low cycle fatigue and ratcheting, but also allows direct estimation of inelastic deformations. This approach, however, can only solve problems at dynamic shakedown, i.e., with limited nonlinearity, and is not capable of providing response time histories. To address these limitations, this paper presents an efficient framework for reliability assessment of inelastic structures at dynamic shakedown and beyond. To this end, a novel step-by-step integration algorithm is developed for rapid response time history analysis within the setting of dynamic shakedown. The method is based on advancing fast nonlinear analysis through introducing schemes for enabling at each time step the adaptive selection of the step size, number of modes to be included, and number of potentially nonlinear elements. Inelasticity is modeled as distributed at the level of the stress resultants through a return mapping scheme based on the Haar–Kàrmàn principle, therefore enabling the integrated estimation of the state of dynamic shakedown. The scheme is seen to preserve the efficiency of recently developed strain-driven dynamic shakedown algorithms while providing a full range of response time histories at and beyond the state of dynamic shakedown. To enable reliability analysis, the scheme is embedded in a general uncertainty propagation framework.

Performance-based wind and earthquake design framework for tall steel buildings with ductile detailing

According to the Canadian building code, wind design relies on prescriptive static methods, which lead to a conservative design. In consequence, in moderate seismic regions where both winds and earthquakes are critical, the size of ductile members resulting from seismic design, and especially those of bottom floors, may not accommodate the elastic wind demand and larger member sizes are required. In general, this is the case of rectangular buildings, where in the direction perpendicular to the largest building dimension, the base shear due to elastic wind demand is critical, while in the orthogonal direction the seismic demand governs. Hence, in one direction, the allowable base shear increases above the seismic demand, which results in reduced energy dissipation and amplification of torsion. To mitigate the incoherence in the current building code, a refined code-based multi-hazard design approach, targeting performance of tall steel buildings in Eastern Canada, is proposed. Thus, accounting for the building’s overstrength and allowing limited controlled inelasticity under high-intensity wind, a wind-related reduction factor RW is proposed to reduce the design wind load. The method is implemented for the design of two identical 15-storey steel braced frame buildings, but of different occupancy, hospital and office, respectively. Nonlinear response history analyses are performed to verify the member sections of steel braced frames, while the parameters investigated are the interstorey drift, residual interstorey drift and floor acceleration. Then, seismic and wind incremental dynamic analyses provide insight into the multi-hazard dynamic response of buildings subjected to ground motions and winds of increasing intensity. The fragility concept is used to quantify the performance of studied buildings designed with RW = 2 versus the building designed with RW = 1. Comfort criteria, as well as, the drift acceptance criteria, commonly considered in research and practice, are used to verify the effectiveness of the proposed method. The nonlinear response of the studied buildings at the design level and beyond shows that using RW = 2 for wind design does not change the response at design level, but slightly decreases the collapse capacity within the acceptable range.

Peak Inelastic Displacement of Bilinear Systems in Support of Performance-Based Wind Design

A fundamental notion in building engineering is the equal displacement rule, which posits that the peak inelastic displacement of a system subjected to a ground motion excitation is approximately equal to the displacement of the same system responding elastically. The purpose of this study is to determine if the equal displacement rule can additionally be applied to wind excitations. To achieve this purpose, bilinear single-degree-of-freedom systems were subjected to B-spline wavelet excitations, Fejér–Korovkin wavelet excitations, and wind excitations derived from wind tunnel tests. The results showed the equal displacement rule generally held for excitations with neutral polarity. The frequency content of the excitation had a significant effect on the response because it shifted the location of the displacement-controlled region of the response spectrum. Duration had a mild effect for excitations with neutral polarity. The effect of stiffness and strength degradation due to gravity loads on the response was more pronounced for short-period structures. For regularly shaped buildings subjected to wind forces, the findings suggest that the equal displacement rule applies in the cross-wind direction however not in the along-wind direction.

Characterizing wind-structure interaction for performance-based wind design of tall buildings

Performance-based wind design (PBWD) has been receiving a great deal of attention from the wind and structural engineering communities. This is specifically highlighted with the release of the ASCE pre-standard for PBWD (2019). The PBWD of tall building requires a series of steps one of which is the interaction parameter, i.e. characterizing the interaction of the tall building with the wind field. In the studies involving slender structures-such as tall buildings, it is essential to consider this interaction parameter which is a function of the time-varying aerodynamic loads. The aerodynamic loads consist of the turbulent loads due to fluctuating wind, known as buffeting loads, and the self-excited loads resulting from the interaction of the structural motions with wind, referred as aeroelastic loads. Flexible structures can become unstable at a critical wind speed, known as flutter speed, wherein a diverging motion of the structure occurs. Aerodynamic instability that is caused by self-excited loads generally doesn’t occur in tall buildings within their design wind speeds but certainly needs to be considered in a wind-structure interaction analysis, particularly when tall buildings become increasingly slender and are allowed to enter post-elastic region. This study aims to characterize the interaction parameter in the PBWD of tall buildings by including the self-excited loads in its response analysis corresponding to the three-degree-of-freedom response motions of the building in along-wind, across-wind, and torsional directions. For this purpose, the flutter derivatives that are used to represent the self-excited loads in frequency domain are first obtained from wind tunnel tests of scaled section models of the structure and then converted into approximate coefficients known as Rational Function Coefficients (RFC) as part of Rational Function Approximations (RFA) of the self-excited loads in Laplace or time domain. The wind loads on a structure in time domain are calculated by combining both the buffeting loads and self-excited loads associated with the calculated RFC. The non-linear structural behavior of a 44-story and a 60-story tall building each is studied using nonlinear dynamic time-history analysis in extreme wind conditions and then observed for any flutter-like instabilities. The concept PBWD is applied considering the performance objective involving those associated with occupant comfort and structural or non-structural damages.

The impact of parameter estimation uncertainty in extreme wind speed models

AbstractAll the available information and uncertainties should be taken into account in a model to give correct answer to a stated problem and evaluate the performance of a structure. This study deals with the impact of parameter estimation uncertainty in extreme wind speeds on the assessed reliability index using frequentist approach. The peak-over-threshold approach with an automated threshold selection method is applied and bootstrapping is used to determine the 95% confidence interval of the estimated reliability index. Based on the results practical recommendations, i.e., a framework of this procedure are derived on how to handle peak-over-threshold in extreme wind speed models for the application of the proposed performance-based wind engineering design.

Uncertainty quantification and probabilistic performance-based assessment of nonlinear behavior of moment resisting frames under design and extreme wind loads

Recent advancements in performance-based assessment and design of buildings subjected to wind loads call for the incorporation of uncertainties in the simulation of both loading and structural response. Additionally, they require a better understanding of nonlinear wind-induced response of buildings. Probabilistic analysis approaches are commonly used for the incorporation of uncertainties in performance-based assessment of building response. These approaches, however, focus more on the wind loading side as opposed to incorporating detailed nonlinear models for the structures. This study leverages SimCenter's newly developed tool WE-UQ to integrate a detailed nonlinear structural model of a 20-story 2D building frame into larger probabilistic simulations. The detailed structural model is created in finite element software OpenSEES and can simulate complex behavior such as stiffness and strength degradation and provide reasonably accurate predictions of yield and collapse. Simulation results are then utilized for probabilistic performance-based assessment of the building frame using the new guidelines proposed by the ASCE pre-standard for performance-based wind design. Additionally, performance of the frame under higher wind speeds that would lead to yielding or collapse of the building is also assessed. The results obtained from the probabilistic simulations are compared with pure deterministic simulation outcomes to investigate the effects and necessity of adding uncertainties into the response prediction of buildings subjected to wind loads.

Performance-based wind design for tall buildings: Review and comparative study

A brief review and state of the art for Performance-Based Wind Design (PBWD) has been presented to provide researchers with clear historic literature on the development of PBWD concepts. The literature clearly emphasizes the main differences between Performance-Based Seismic Design (PBSD) and Performance-Based Wind Design and the challenges incurred. The study presents a brief description of the current prescriptive approaches and the challenges and limitations to their use and the broad wide range of research areas in Performance-Based Design (PBD). It also highlights the nonlinear inelastic response studies for structures subjected to wind loads and the envelope performance for structures. Immense efforts have been made to develop the PBD concepts, and similar to PBSD, the PBWD approach has shown great potential, yet it has several uncertainties that need further investigation. Those PBWD approaches will have a tangible effect on the design concepts and consequently on the design of the fast-growing tall buildings for more resilient communities subjected to extreme wind events and accordingly, more economic designs. Wind tunnels and reliable Computational Fluid Dynamics (CFD) analysis can help in developing concepts and provide a dynamic load time history which will greatly help in Performance-Based Wind Engineering. The incorporation of field data on non-structural elements' performance during non-synoptic wind incidents (i.e., hurricane and thunderstorm events) into the simulation and analytical models is still under development and shows high potential and promising research outcomes that would help in developing more accurate damage evaluation and serviceability satisfaction. A comparative case study was also presented for the responses under wind and seismic forces. From the study, it can be concluded that PBWD has potential in some cases especially if the governing wind case is the across-wind case, where a significant reduction in base shear and moment values (∼50%) was observed when the building stiffness decreased. On the other hand, when the along-wind load is the governing load case, decreasing the building's stiffness has led to higher base forces (∼100% increase in the responses). However, further investigation is needed to study different aspect ratios and shapes and include more frequency ranges.

Wind-induced fragility of a monopole structure via Artificial Neural Network based surrogate analysis

Although brute-force Monte Carlo (BFMC) sampling has been commonly used in performance-based wind engineering (PBWE) due to its robustness and efficiency, the computing cost required by the considerable amounts of repetitious, stochastic realizations for situations that involve large structures and a multitude of uncertainties is still prohibitive. To alleviate the computational burden, this communication proposes a surrogate modeling approach, based on artificial neural networks (ANNs), to evaluate the probabilistic integral required to quantify wind-induced fragilities. The resultant ANN models form a computationally viable alternative between input and output variables, based on a database of observations obtained through BFMC stochastic simulations. A preliminary study is conducted to examine the fragility of a slender, monopole tower structure under the excitation of multidirectional, mixed-climate wind loads. The ANN-powered surrogate results show adequate accuracy while drastically reducing the computing time to less than 1% of the cost of BFMC approach. It is promising to incorporate the surrogate ANN modeling in a PBWE framework.

An efficient stratified sampling scheme for the simultaneous estimation of small failure probabilities in wind engineering applications

With the advent of performance-based engineering frameworks for extreme winds, greater efficiency in the estimation of failure probabilities associated with multiple limit states at ultimate load levels, including collapse, is required. To meet this demand, an optimal stratified sampling-based simulation scheme is proposed that shares several meritorious characteristics of standard Monte Carlo simulation (MCS), including the capability to deal with high-dimensional uncertain spaces and multiple limit state functions. The optimality of the scheme is governed by the allocation of MCS samples among the strata as well as the strata division itself. A constrained optimization problem is formulated to address efficient sample allocation which is an extension of the Neyman allocation. Details for the practical implementation of the scheme within wind engineering reliability assessment applications are discussed. It is observed that the proposed methodology can reduce the variance by several orders of magnitude compared to MCS, which is illustrated on a wind-excited steel structure for the limit states of member/system first yield and collapse. The applicability of Latin hypercube sampling within stratified sampling-based simulation and the resulting efficiency gains are also critically studied. The results show promise in the wider applicability of the proposed scheme in performance-based wind engineering.

Wind-Induced Impact Behavior of Base-Isolated High-Rise Buildings with Adjacent Structures

The base-isolation technology has been increasingly applied in high-rise buildings in recent years. Previous studies have shown that the unfavorable wind-induced response can be effectively reduced by a certain degree of hysteretic energy dissipation after the yielding of the isolation system under strong wind load. However, a large relative inelastic displacement at the isolation level will occur under this condition, which is likely to exceed the width of seismic gap, and cause a structural impact with the adjacent structures (i.e. retaining wall or other barriers). Such wind-induced impacts may have detrimental consequences on the structural performance and have not been investigated much before. This study prospectively investigated the wind-induced impact behavior of base-isolated high-rise buildings with adjacent structures. The multi-story superstructure is modeled as a linear elastic shear building, while the isolation system is represented by bilinear hysteresis restoring force model. An impact element combined with linear spring and damper is used. The story wind load is determined by its cross power spectral density (PSD). Responses for two kinds of typical impact including crosswind and along-wind impact are examined by time history analysis. The results demonstrate that the impact will increase the fluctuation components of superstructure displacement, shear force and bending moment to some extent compared with that of the base-isolated building without impact. The floor accelerations, especially floors close to the base, are significantly increased during impact. The impact has no effect on the mean component of each response. At last, a parametric analysis is carried out to explore the influences of various impact parameters on the inelastic impact response. The results of this study can help to better understand the impact behavior of base-isolated high-rise buildings under strong wind excitation and be useful for performance-based wind resistance design.

Wind fragility assessment and sensitivity analysis for a transmission tower-line system

Wind fragility is essential to performance-based wind engineering, risk, and resilience assessment for transmission towers. However, it has not been sufficiently studied due to the key issues in performance evaluation and uncertainty treatment for transmission towers. The performance of high-rise structures can be severely weakened by geometric imperfections, but these impacts have not been well addressed for transmission towers. Besides, the current uncertainty treatment only considers the tower itself although the transmission tower is part of an interconnected tower-line system that has complex interactions with wind environment. Therefore, this paper provides a systemic solution for geometric imperfections of transmission towers, where the users can clearly observe the effect of geometric imperfections on the capacity and failure positions of transmission towers. On this basis, a wind fragility framework that incorporates the uncertainties of each line component, wind environment, and aerodynamic parameters is proposed for transmission towers. Finally, sensitivity analysis was conducted to identify the significant uncertainty parameters for tower capacity and demand by sensitivity diagram. It is found that in addition to the uncertainties of the tower itself, the uncertainties of wind profile exponent, outer diameter and aerodynamic parameter of conductors have significant effects on the fragility of transmission towers.

Performance-Based Wind Design of Tall Buildings Considering the Nonlinearity in Building Response

Performance-Based Wind Design of Tall Buildings Considering the Nonlinearity in Building Response