Seymour M.J. Spence

Tall Buildings and Damping: A Concept-Based Data-Driven Model

AbstractModern tall buildings are characterized by their slenderness and sensitivity to resonant wind effects. This is especially true considering the acceleration-based motion perception criteria under which they must be designed. In light of the significance of the resonant response, damping plays an important role in the design of tall buildings. Unfortunately, unlike other mechanical characteristics of structures, damping is far more difficult to estimate. This is due to the inherent complexity and high number of mechanisms responsible for damping. For this reason, the experimental determination of damping levels for tall buildings from full-scale data collected during monitoring programs has obtained a tremendous amount of interest over the past years. This paper firstly reviews the predictive damping models that are available in the literature highlighting their merits and shortcomings in light of the extensive experimental damping data collected over the past few years. A novel amplitude-dependent ...

Performance-Based Design of High-Rise Buildings for Occupant Comfort

AbstractThis paper introduces a framework for the performance-based design (PBD) of high-rise buildings with respect to the occupant comfort performance objective. The performance is expressed in terms of the probability—conditional on the wind event intensity—that the fraction of the building occupants on one floor that perceive the motion is greater than a chosen threshold value. The framework is fully probabilistic, and numerous uncertainties affecting both the structural response and the human perception threshold are considered in the assessment of the exceedance probability. In addition, a new database-enabled online analysis module based on the proposed PBD framework [Performance-Based Data-Enabled Design module for Occupant Comfort (PBDED-OC)] is presented. The PBDED-OC allows the assessment of the occupant comfort performance of a tall building by taking advantage of databases of high-frequency base balance measurements or by adopting specific user-supplied wind tunnel data and is envisaged to be...

A cyberbased Data-Enabled Design framework for high-rise buildings driven by synchronously measured surface pressures

Abstract This study presents a new Data-Enabled Design Model for high-rise buildings driven by pressure datasets, DEDM-HRP, which seamlessly combines synchronous pressure measurement databases with a rigorous computational framework to offer convenient estimation of wind load effects on high-rise buildings for their preliminary design. To respond to the need for practical applications, DEDM-HRP employs a web-based on-the-fly framework designed with user-friendly/intuitive web interfaces for the assessment of wind-induced responses as well as equivalent static wind loads in the three principal response directions, for any incident wind angle of interest, with minimum added complications or requirements of knowledge of comprehensive background theories for its use.

Performance Evaluation of Database-Enabled Design Frameworks for the Preliminary Design of Tall Buildings

AbstractDatabase-enabled design (DED) frameworks offer convenient meshing of wind-tunnel driven databases with state-of-the-art analysis methodologies for the design of low-rise to high-rise buildings. These procedures can serve as an alternative or supplementary tool to codes and standards. Despite their obvious advantages over simplified code-specified procedures, the response estimates obtained from these data-driven frameworks are by nature susceptible to the accuracy of both the analysis schemes employed within the procedure as well as the aerodynamic databases that are driven by different wind tunnels, instrumentations, and experimental techniques. To examine and quantify these potential sources of discrepancy, this paper attempts to evaluate the performance of various cyber-based DED frameworks that are currently used in the preliminary design of tall buildings. To this end, a systematic comparison is carried out among along-wind and across-wind response estimates of a typical building example usin...

Control of the wind induced response of structures

In recent years, a drive towards the construction of buildings of increasing heights and bridges of increasing span lengths has generated the most fascinating challenges in the civil engineering field. Indeed, the particular sensitivity to wind loads of such extreme structures has to be faced when designing structural systems that have to possess adequate stiffness and damping characteristics to ensure acceptable performance for survivability, serviceability and habitability. In order to meet these needs, several routes can be taken that involve different design aspects. In addition to the modification of the structural system, which is the first and foremost option for the structural designers, these can be divided in the adoption of shape tailoring measures, aimed at improving the aerodynamics/aeroelasticity of the structure, and the introduction of auxiliary motion control devices. In this chapter these two aspects are treated, with the intent of providing the reader with a general overview of the engineering solutions that may be considered for the control of the wind induced response of structures. In particular, discussion on the aerodynamic/aeroelastic shape tailoring is provided, alongside with meaningful examples of application of this strategy to real structures. The possibility of adopting motion control devices is also investigated. The most important typologies of devices for the control of wind induced vibrations are classified according to the principle on which they are based and their main characteristics are illustrated.

A Performance-Based Methodology for the Topology Design of Tall Buildings

Topology optimization methods have recently been used as a tool for conceptual tall building design. These techniques were originally developed in a deterministic setting despite the inherently uncertain nature of the real-world environment. If uncertainties are neglected during the design process there is a possibility that the final constructed designs may perform unsatisfactorily. Thus it is necessary to account for uncertainties affecting the problem, including stochastic environmental loads and time-invariant uncertainties. Furthermore, the dynamically sensitive nature of tall buildings must be considered during the design process. This paper presents a methodology for the topology optimization of tall buildings in this setting using a framework based on the PEER Equation. A novel decoupling approach is developed that defines approximate sub-problems that can be solved using established topology optimization techniques. The successive resolution of the sub-problems until convergence results in an optimal design that satisfies the original performance constraints. A case study is used to demonstrate the validity of this framework.

Turbulence model verification and validation in an open source environment

In this paper, the verification of two low-Reynolds-number turbulence models in an open source environment is reported. The two models are the Spalart-Allmaras model without the ft2 term and the k – ω SST model using vorticity in production estimation. Grid convergence is achieved in all verification cases, while reasonable agreements with other codes are found. The two turbulence models are also validated through comparison with some well-known validation cases, the results of which show good agreement with experimental data. The differences between the results obtained from incompressible and compressible codes are also discussed. The impact of wall distance estimation on the performance of turbulence modelling is also evaluated through grid convergence studies. Within the realm of search algorithms for wall distance estimation, a three-level search approach is found to be necessary in order to achieve correct and converged results, especially for skewed meshes. It is shown, through a 2D bump flow grid convergence study, that the use of a one-level search approach can not only lead to a maximum friction coefficient deviation of 3.8%, but also cause an inconsistent convergence behaviour.

Topology optimization for buildings in seismic zones within a pbee framework

This paper presents a probabilistic performance-based topology optimization framework for the conceptual design of uncertain building systems in seismic zones. The stochastic nature of the ground motions is rigorously considered in a simulation-based probabilistic performance assessment framework that allows for the definition of a novel decoupling technique that efficiently separates the probabilistic analysis from the optimization loop. In particular, the methodology is based on the construction of a series of approximate sub-problems with simplified governing equations, which conveniently allows their evaluation using established techniques for static, deterministic topology optimization problems. The applicability and efficiency of the method is demonstrated on a case study.