Performance-based Wind Research Articles

Performance-based wind-induced structural and envelope damage assessment of engineered buildings through nonlinear dynamic analysis

Performance-based wind engineering (PBWE) is undergoing a period of rapid development with numerous procedures and frameworks being proposed over the past few years. Notwithstanding these advancements, there is still a knowledge gap concerning the relative severity, dependency and rate of occurrence of structural and envelope damage in extreme wind events. This work is focused on investigating this problem for engineered buildings. In particular, envelope damage is estimated through a recently introduced PBWE framework that explicitly includes the effects of demands originating from dynamic net pressure and the structural responses. Structural damage is estimated through both fragility analysis as well as material yielding/hysteresis modeled through the adoption of a nonlinear fiber-based finite element formulation. Structural responses include the effects of large deformations through solving the finite element model in a corotational environment. To investigate the relative severity and dependency between the damages, a carefully calibrated archetype 45-story steel building located in Miami, FL, and subject to hurricane winds is studied. Probabilistic damage metrics are estimated for both the envelope and structural systems and are subsequently discussed in terms of relative severity, occurrence rates and nonlinear structural behavior.

Knowledge-Enhanced Deep Learning for Wind-Induced Nonlinear Structural Dynamic Analysis

AbstractRecent advancements of performance-based wind design of tall buildings have placed increasing importance on effectively modeling of the nonlinear structural dynamic response under extreme s...

Performance-based wind design of tall buildings: concepts, frameworks, and opportunities

One of the next frontiers in structural wind engineering is the design of tall buildings using performance-based approaches. Currently, tall buildings are being designed using provisions in the building codes and standards to meet an acceptable level of public safety and serviceability. However, recent studies in wind and earthquake engineering have highlighted the conceptual and practical limitations of the code-oriented design methods. Performance-based wind design (PBWD) is the logical extension of the current wind design approaches to overcome these limitations. Towards the development of PBWD, in this paper, we systematically review the advances made in this field, highlight the research gaps, and provide a basis for future research. Initially, the anatomy of the Wind Loading Chain is presented, in which emphasis was given to the early works of Alan G. Davenport. Next, the current state of practice to design tall buildings for wind load is presented, and its limitations are highlighted. Following this, we critically review the state of development of PBWD. Our review on PBWD covers the existing design frameworks and studies conducted on the nonlinear response of structures under wind loads. Thereafter, to provide a basis for future research, the nonlinear response of simple yielding systems under long-duration turbulent wind loads is studied in two phases. The first phase investigates the issue of damage accumulation in conventional structural systems characterized by elastic-plastic, bilinear, pinching, degrading, and deteriorating hysteretic models. The second phase introduces methods to develop new performance objectives for PBWD based on joint peak and residual deformation demands. In this context, the utility of multi-variate demand modeling using copulas and kernel density estimation techniques is presented. This paper also presents joined fragility curves based on the results of incremental dynamic analysis. Subsequently, the efficiency of tuned mass dampers and self-centering systems in controlling the accumulation of damage in wind-excited structural systems are investigated. The role and the need for explicit modeling of uncertainties in PBWD are also discussed with a case study example. Lastly, two unified PBWD frameworks are proposed by adapting and revisiting the Wind Loading Chain. This paper concludes with a summary and a proposal for future research.

A Performance-Based Wind Engineering Framework for Envelope Systems of Engineered Buildings Subject to Directional Wind and Rain Hazards

AbstractThe adoption of performance-based wind engineering (PBWE) is rapidly becoming recognized as a fundamental step to reducing the huge economic losses caused by severe windstorms. This has led...

Performance-Based Wind Engineering of Tall Buildings Examining Life-Cycle Downtime and Multisource Wind Damage

AbstractStructural performance against wind hazards is necessary in modern tall building design. In current wind engineering practice, most efforts focus on structural safety, such as the avoidance...

A new stochastic formulation for synthetic hurricane simulation over the North Atlantic Ocean

Hurricanes are among the most destructive weather phenomena in the United States (US) of America. Accurate modeling of hurricane trajectories, as they land ashore and approach the built environment, is important for public safety. This study presents a new stochastic model for the simulation of hurricane trajectories in the North Atlantic Ocean. Trajectory of the hurricane eye is modeled as a two-dimensional partially-correlated Brownian motion with drift term. Hurricane intensity is modeled as a second-order auto-regressive process, accounting for sea surface temperature.The model is validated by comparing the numerically-generated hurricane tracks against historical records, derived from the HurDat database (NOAA, National Oceanic and Atmospheric Administration). Simulated hurricane arrival and landing rates along the US Eastern coastline are also examined to demonstrate model validity. Finally, performance-based wind engineering (PBWE) application is presented by comparing simulated hurricane wind speeds against ASCE 7-16 recommendations.

Performance-Based Wind-Resistant Optimization Design for Tall Building Structures

This paper presents a novel framework for the performance-based wind-resistant design of tall buildings accounting for the joint probability distribution of wind speed and direction obtained from long-term wind measurements of local meteorological stations. The joint probability distribution of the wind speed and direction, as well as the uncertainties and probability distributions of natural frequencies and damping ratios, are integrated to investigate the realistic structural performance of optimized target buildings under the wind action. A procedure on the performance-based wind-resistant optimization design of tall buildings is then proposed by adopting the optimality criteria algorithm. The proposed framework is applied to the Commonwealth Advisory Aeronautical Research Council building; the total weight and sizes of structural members are selected as the objective function and design variables in the optimization process, respectively. Compared with the deterministic constraints adopted in the conventional optimization procedure, the optimization constraint conditions in this paper are expressed by the failure probabilities in terms of the maximum displacement, interstory drift, and wind-induced acceleration responses at different design levels, which are associated with different return periods required by the strength and serviceability criteria in the performance-based wind engineering design. The mapping transformation method and checking point algorithm in structural reliability theory are adopted to conduct reliability analysis on the probability constraints in the optimization procedure. The optimized results are analyzed and discussed in the numerical example to verify the effectiveness of the proposed performance-based wind-resistant optimization design of tall buildings.

An efficient framework for the inelastic performance assessment of structural systems subject to stochastic wind loads

The modeling and estimation of the inelastic response of wind excited structures is attracting growing interest with the introduction of performance-based wind engineering. While frameworks based on direct integration have been widely adopted in earthquake engineering for estimating inelastic responses, the significantly longer duration of typical windstorms, as compared to seismic events, makes this approach extremely computationally challenging in the case of wind excited systems. This is especially true in the case of modern performance-based wind engineering frameworks, which are based on probabilistic metrics estimated through simulation and therefore repeated evaluation of the system. This paper addresses this challenge through the development of a simulation framework based on dynamic shakedown theory. In particular, an efficient path-following algorithm is proposed for estimating not only the shakedown multipliers, but also the plastic strains and deformations associated with occurrence of the state of shakedown. The efficiency with which this information can be estimated for any given wind load time history enables the development of a simulation-based framework, driven by general stochastic wind load models, for the estimation of the system-level inelastic performance of the structure. The validity and practicality of the proposed framework is illustrated on a large-scale case study.

Probabilistic serviceability-performance assessment of tall mass-timber buildings subjected to stochastic wind loads: Part I - structural design and wind tunnel testing

Tall mass-timber buildings utilize engineered wood panels to form their main gravity and lateral load resisting systems, which makes them lighter and very flexible. As a result, frequent exposure to excessive wind-induced vibrations can cause occupant discomfort and unserviceability due to horizontal floor acceleration and excessive deflection. Therefore, the objective of this and the companion paper is to assess the serviceability performance of tall mass-timber buildings probabilistically. For this purpose, the Alan G. Davenport Wind Loading Chain is adapted as a probabilistic Performance-Based Wind Engineering framework. The framework is applied to quantify the serviceability performance of a 102-m tall mass-timber building. In this paper, a complete tall-mass timber building structural design process is outlined. Wind loads are obtained from aerodynamic wind tunnel tests conducted at the Boundary Layer Wind Tunnel Laboratory at Western University. The design process involves preliminary strength design using the provisions of building codes, design revisions using wind load from wind tunnel tests, and serviceability checks. The structural design of the case study tall mass-timber building considers the axial compression, in-plane-shear, and in-plane and out-of-plane bending moment demands, along with their interactions due to gravity and wind loads. Dynamic analysis is carried out to assess the drift performance of the case study mass-timber building. The results show that the building satisfies the drift requirements prescribed by the building codes with a small safety margin. For the designed tall mass-timber building, an in-depth probabilistic serviceability-performance assessment and vulnerability estimations are presented in the companion paper.

Probabilistic serviceability-performance assessment of tall mass-timber buildings subjected to stochastic wind loads: Part II - structural reliability analysis

In this paper, the second of two companion papers, the serviceability-performance of a tall mass-timber building is evaluated probabilistically. For the assessment, the Alan G. Davenport Wind Loading Chain is adapted to a probabilistic Performance-Based Wind Engineering (PBWE) framework. The framework allows incorporation of uncertainties at each step of the wind loading chain, i.e., local wind climate and exposure, aerodynamics, dynamic effects, and criteria. As a case study, the framework is applied to quantify the serviceability-performance of a 102-m tall mass-timber building. Initially, parametric analyses are carried out to study the influence of critical damping ratio, wind direction, and local turbulence intensity on the response of the case study tall mass-timber building. Results showed the dependence of story level structural responses on the studied parameters and hence the need to consider the role of uncertainties. Therefore, uncertainties in various parts of the Wind Load Chain are explicitly modeled using fifteen random variables. Structural reliability analysis using Monte Carlo sampling is performed to propagate the uncertainties through the Wind Loading Chain. The results from reliability analysis are used to develop fragility curves for wind vulnerability estimations. Based on the results, design recommendations based on building functionality are forwarded.

A unified framework for performance-based wind engineering of tall buildings in hurricane-prone regions based on lifetime intervention-cost estimation

Accurate evaluation of structural performance is necessary in modern tall building design. In wind engineering, the current approach employed by researchers is the Monte-Carlo sampling method. Structural failure probability is calculated by combining structural fragility curves with the random variability of wind speed and direction, depending on local wind climate. In the hurricane-prone regions of the USA, wind climate and its effects on building response require accurate assessment of wind-induced structural performance.This paper proposes a simulation framework for tall buildings that combines fragility analysis with local wind climate information to evaluate structural vulnerability. Hurricane wind climate information directly considers maximum wind speed, wind direction along with their correlation at hurricane landfall. Consequently, structural fragility surfaces will be generated, conditional on these two variables. This result will be used to examine lifetime intervention cost accumulation, associated with nonstructural damage on the building façade, and to determine an “optimal” wind-direction-dependent building orientation.

Risk Analysis of Three-storey Reinforced Concrete Moment-resisting Frame Structures Using Performance-based Wind Engineering

This paper discusses the application of concepts of performance-based wind engineering used to determine the effects of changing building design elements to the performance of a structure against severe wind hazards in the Greater Metro Manila Area, Philippines. Only three-storey reinforced concrete moment-resisting frame structures were subject to analysis through computational fluid dynamics. Before assessing the performance of structures, severe wind hazards for the study area was characterized by collecting wind speed data from over 50 years and fitting the data using the Gumbel distribution. The building stock was developed by varying roof pitch and floor aspect ratio values in certain set increments. Roof pitches observed were 15, 30, and 45 along with structures with floor aspect ratios of 1:1, 1:2, and 1:3. The damage to roof and windows, as well as the damage index which gives the ratio of the repair cost to the replacement cost of a building, were identified. Damage for each model was classified according to the Hazard-US Damage State Matrix in order to generate a damage probability matrix. From this damage probability matrix, the probability of exceedance of each damage state was compute by taking the cumulative probabilities. Data points for each damage state were then fitted with a lognormal function. Vulnerability curves were developed by multiplying the probability of exceedance of each damage state to cost percentages adopted from the UPD-ICE Report [2]. Damage indices were computed per wind speed by summing the total damage for damage states. Wind speed versus risk density curves were generated by multiplying values for each data point in the vulnerability curves to the probability density function of the hazard. Risk curves were then obtained by plotting wind speeds against values of damage indices that correspond to said wind speeds. One key observation is that damage percentage increased as roof pitch also increased, having as much as around a 15% difference between structures with roof pitches of 15 and 45. Slender structures whose windward sides were also the long sides had the most damage. For all structures, a top-to-bottom progressive damage trend was observed.

Examination of experimental variability in HFFB testing of a tall building under multi-directional winds

Examination of wind loading uncertainty is necessary for structural fragility analysis of tall buildings in the context of performance-based wind engineering. One of the sources of uncertainly is represented by random experimental error, which may occur during a standard test in wind tunnel, such as the high frequency force balance (HFFB) test. Few examples of systematic experimental error analysis are available. This study examines a series of experiments on a model of a standard benchmark building under simulated turbulent flow. HFFB experiments were conducted in the Northeastern University's small-scale wind tunnel. Three model equations are proposed to represent the power spectral density (PSD) functions of the above three forces in the frequency domain.Furthermore, effects of experimental errors are incorporated by allowing the parameters in each function to vary randomly. Variability is evaluated by considering the second-order statistical moments of the parameters (standard deviations and correlations). At last, this paper introduces a data-driven Monte-Carlo approach to reconstruct the generalized PSD of the wind loading through model equations. Experimental variability is accounted for by exploiting information on the probability distributions of the model parameters. Verification of the reconstructed PSD functions against experiments suggests that the Monte-Carlo approach can effectively generate synthetic PSD curves.

A performance-based design framework for the integrated collapse and non-collapse assessment of wind excited buildings

Current prescriptive design provisions are moving towards performance-based design approaches in which system-level probabilistic measures are used to explicitly describe performance. While earthquake engineering has embraced these changes over the last few decades, the same cannot be said for wind engineering where design provisions have remained predominantly prescriptive. The significant wind related economic losses incurred each year around the world has spurred strong interest in developing general performance-based wind engineering frameworks. To this end, this paper presents a simulation-based framework for multistory wind excited buildings that rigorously integrates system-level estimates of both collapse and non-collapse losses. In particular, it is proposed to use the theory of dynamic shakedown as an efficient means for describing the collapse probability of the main wind force resisting system. The practicality and potential of the proposed framework is illustrated on a full scale case study.

Performance-based design of steel towers subject to wind action

Performance-based Wind Engineering (PBWE) is a novel design philosophy that aims to identify and quantify the uncertainties involved in structural design, in order to ensure predictable performance levels to engineering structures. Due to the recent proposal of the methodology and formulation complexity, there are few studies related to PBWE, each presenting different limitations. This paper proposes an application of the Performance-based Wind Engineering methodology to the probabilistic analysis of steel towers, evaluating different calculation models for the estimation of wind forces on this type of structure. Uncertainties involved in the characterization of the wind field and the structural strength were investigated, and two procedures of the Brazilian winds standard NBR6123:88 for the estimation of wind forces on steel towers were analyzed. A case study concerning the reliability estimation of a telecommunication tower was also conducted. It was found that both studied calculation models lead to similar safety levels, and that the design of towers considering that wind always blows from the worst direction is too conservative. It is also shown that, in PBWE, minimum cost design can be guided by assigning same target reliability, but different mean recurrence intervals for different performance levels.

Experimental analysis of a stochastic model for estimating wind-borne compact debris trajectory in turbulent winds

The impact of flying debris against building envelopes during high winds is a major source of structural damage. For example, damage produced by Hurricanes Katrina and Ike in the United States on the facades of tall buildings, located in urban areas, has been documented. It is therefore of relevance to analyze the vulnerability of tall buildings to debris-induced non-structural damage in the general context of performance-based wind engineering. In order to analyze the random trajectory of debris in highly turbulent winds, a numerical model combined with a probability-based algorithm was recently proposed by the authors (Moghim and Caracoglia, 2013). This model investigates the trajectory of “compact debris”, defined as point-mass objects of negligible mass moments of inertia and for which the aerodynamics is predominantly controlled by the drag force. The model replicates both the inherent randomness in debris properties and the effect of wind shear and atmospheric turbulence to estimate debris trajectory and the likelihood of impact against vertical building facades in a probabilistic setting.This paper describes the comparison between numerical model results and wind tunnel experiments. Tests were carried out in the Northeastern University׳s small scale wind tunnel in both smooth flow and grid-generated turbulent flow. The motion of spheres and cubes, simulating compact debris objects, was investigated in two dimensions (2D) on a vertical plane.The 2D motion of compact objects of various sizes was captured by a high-speed digital camera at different flow speeds. Experimental results showed to be consistent with numerical simulations. They also confirmed that not only mean flow speed but also turbulence features can have a non-negligible effect on the trajectory of compact objects.

Performance-based design optimization of tall concrete framed structures subject to wind excitations

This paper presents an integrated computational design optimization method for the performance-based design of tall buildings subjected to various levels of wind excitation. A performance-based wind engineering design framework is proposed by defining various performance objectives associated with multiple levels of wind hazards. A nonlinear static pushover analysis is employed to predict the inelastic drift performance of tall buildings subject to very rare extreme wind events. The optimal performance-based design problem considering inelastic deformation is formulated and solved by the augmented optimality criteria method. The effectiveness and practicality of the optimal wind-resistant performance-based design technique are illustrated by a practical 40-story residential building.

A stochastic model for examining along-wind loading uncertainty and intervention costs due to wind-induced damage on tall buildings

This study describes some recent results of a numerical study on the wind-induced response of a tall building, contaminated by along-wind loading uncertainty. The study also proposes the use of “intervention costs” in the form of a dimensionless random variable, which nonlinearly depends on the dynamic response of the structure, for the examination of the structural performance during high-wind events.The CAARC building is employed as the benchmark structure. Three nonlinear reduced-order models are used to describe the dynamic response. In these models various hypotheses are introduced to systematically and efficiently simulate both loading uncertainty and cost variability. The generalized models are formulated in terms of stochastic differential equations and are approximately solved by equivalent stochastic linearization. In the case of loading uncertainty analysis, the joint probability density function of the roof-top lateral dynamic displacements in the two primary bending planes of the building is determined as a function of the mean wind speed and the standard deviation of a parametric error term. Dependence of the cross-correlation among the two response components on the input standard deviation of the parametric error term is observed. In the case of the intervention cost analysis, it is noted that the main contributing factor to the distribution of the intervention cost random variable is the mean wind speed.The combination of wind loading uncertainty and projected intervention costs on the dynamic response of the structure is the first step towards the implementation of alternative but rational analysis methods for performance-based wind engineering, applied to tall buildings.

Risk design optimization using many-objective evolutionary algorithm with application to performance-based wind engineering of tall buildings

Risk design optimization (RDO) is a competent approach for automated performance-based structural design by achieving a balance between safety and economy. Performance-based wind engineering (PBWE) is aimed at improving the life-cycle functionality of wind-sensitive structures, hence could be the very field RDO is tailor-made for. In this paper, we embed PBWE of tall buildings into RDO and tackle some difficulties when integrating them directly. We first formulate an integrated stiffness and vibration control RDO problem, and employ a frequency domain closed-form solution for uncertainty quantification and uncertainty propagation through the excitation–response–performance chain. Then we reveal the multi-objective optimization nature of RDO, and circumvent the difficulties in serviceability loss estimation by replacing scalar total cost with high-dimensional objective vector. Micro multi-objective particle swarm optimization in conjunction with kernel-learning based principle component analysis is employed to solve the corresponding many-objective problem with multiple probabilistic constraints and discrete design variables. The optimization results of CAARC benchmark indicate that we simplify risk-based PBWE of tall buildings from a complex multi-objective decision making process into a relatively easy multi-attribute decision making process. Accordingly, convincing decisions can be made based on the explicit building performance rather than the unreliable loss information.

Peak Distributions and Peak Factors of Wind-Induced Pressure Processes on Tall Buildings

The emergence of performance-based wind engineering calls for improved probabilistic modeling of wind effects on buildings. This paper focuses on the development of probabilistic models of the peak distribution and peak factor for non-Gaussian processes and explores the applications of this development in wind engineering. The closed-form expressions for the mean, SD, and fractile levels of extremes are derived for a random process whose peaks are modeled by the parametric Weibull distribution. A new translated-peak-process method is then developed for the estimation of the peak distribution, peak factor, and variability of extremes, based on the Weibull distribution and point-to-point mapping procedure. The proposed translated-peak-process method is validated by wind-tunnel pressure measurements on a standard tall building and is shown to be more robust and practical than many existing methods in analyzing non-Gaussian wind pressure data.