TY - JOUR
A1 - Kavrakov, Igor
A1 - Legatiuk, Dmitrii
A1 - Gürlebeck, Klaus
A1 - Morgenthal, Guido
T1 - A categorical perspective towards aerodynamic models for aeroelastic analyses of bridge decks
JF - Royal Society Open Science
N2 - Reliable modelling in structural engineering is crucial for the serviceability and safety of structures. A huge variety of aerodynamic models for aeroelastic analyses of bridges poses natural questions on their complexity and thus, quality. Moreover, a direct comparison of aerodynamic models is typically either not possible or senseless, as the models can be based on very different physical assumptions. Therefore, to address the question of principal comparability and complexity of models, a more abstract approach, accounting for the effect of basic physical assumptions, is necessary.
This paper presents an application of a recently introduced category theory-based modelling approach to a diverse set of models from bridge aerodynamics. Initially, the categorical approach is extended to allow an adequate description of aerodynamic models. Complexity of the selected aerodynamic models is evaluated, based on which model comparability is established. Finally, the utility of the approach for model comparison and characterisation is demonstrated on an illustrative example from bridge aeroelasticity. The outcome of this study is intended to serve as an alternative framework for model comparison and impact future model assessment studies of mathematical models for engineering applications.
KW - Brücke
KW - Aerodynamik
KW - Aeroelastizität
KW - bridge
KW - abstract modelling
KW - category theory
KW - bridge aerodynamics
KW - bridge aeroelasticity
KW - aerodynamic models
KW - model complexity
Y1 - 2019
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20190314-38656
UR - https://royalsocietypublishing.org/doi/10.1098/rsos.181848
IS - Volume 6, Issue 3
ER -
TY - THES
A1 - Damanik, Batta Septo Van Bahtiar
T1 - Aerodynamic Analysis of Slender Vertical Structure and Response Control with Tuned Mass Damper
N2 - Analysis of vortex induced vibration has gained more interest in practical held of civil engineering. The phenomenon often occurs in long and slender vertical structure like high rise building, tower, chimney or bridge pylon, which resulting in unfavorable responses and might lead to the collapse of the structures. The phenomenon appears when frequency of vortex shedding produced in the wake area of body meet the natural frequency of the structure. Even though this phenomenon does not necessarily generate a divergent amplitude response, the structure still may fail due to fatigue damage.
To reduce the effect of vortex induced vibration, engineers widely use passive vibration response control system. In this case, the thesis studies the effect of tuned mass damper. The objective of this thesis is to simulate the effect of tuned mass damper in reducing unfavorable responses due to vortex induced vibration and initiated by numerical model validation with respect to wind tunnel test report. The reference structure that being used inside the thesis is Stonecutter Bridge, Hongkong.
A numerical solver for computational uid dynamics named VX ow which developed by Morgenthal [6] is utilized for wind and structure simulation. The comparison between numerical model and wind tunnel result shows 10% maximum tip displacement diference in the model of full erection freestanding tower. The tuned mass damper (TMD) model itself built separately in finite element software SOFiSTiK, and the efective damping obtained from this model then applied inside input modal data of VX ow simulation. A single TMD with mass ratio of TMD 0.5% to the mass of first bending frequency, the maximum tip displacement is measured to be average 67% reduced.
Considering construction limitation and robustness of TMD, the effects of multiple TMD inside a structure are also studied. An uncoupled procedure of applying aeroelastic loads obtained from VX
ow inside finite element software SOFiSTiK is also done to observe the optimum distribution and optimum mass ratio of multiple tuned mass damper. The rest of the properties of TMD are calculated with Den Hartog's formula. The results are as follows: peak displacement in the case of multiple TMD that distributed with polynomial spacing achieve 7.8% more reduction performance than
the one that distributed with equal spacing. Optimum mass of tuned mass damper achieved with ratio 1.25% mass of first bending frequency corresponds to across wind direction.
KW - aerodynamic
KW - wind
KW - tuned mass damper
KW - bridge
KW - structure
KW - Aerodynamic
Y1 - 2015
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20151030-24714
ER -
TY - THES
A1 - Bayer, Veit
T1 - Zur Zuverlässigkeitsbeurteilung von Baukonstruktionen unter dynamischen Einwirkungen
T1 - On the reliability assessment of building structures subjected to dynamic excitation
N2 - Die Arbeit befaßt sich mit varianzmindernden Verfahren zur Monte Carlo Simulation von stochastischen Prozessen, zum Zweck der Zuverlässigkeitsbeurteilung von Baukonstruktionen mit nichtlinearem Systemverhalten. Kap. 2 ist eine Literaturstudie zu varianzmindernden Monte Carlo Methoden. In Kap. 3 wird die Spektrale Darstellung eines stationären, skalaren Gauß - Prozesses hergeleitet. Auf dieser Grundlage werden verschiedene Simulationsmodelle diskutiert. Das in Kap. 4 entwickelte varianzmindernde Simulationsverfahren basiert auf der Spektralen Darstellung. Nach einer ersten Pilotsimulation werden die Frequenzen für die Einführung zufälliger Amplituden bestimmt und deren Parameter angepaßt. Der zweite Lauf erfolgt mit diesen Parametern nach dem Prinzip des Importance Sampling. Das Verfahren wird in Kap. 5 für eine Brücke unter Erdbebenbelastung angewendet. Die Brücke ist mit sog. Hysteretic Devices zur Energiedissipation ausgerüstet. Es werden einerseits die Genauigkeit und Effizienz des Simulationsverfahrens, andererseits die Leistungsfähigkeit der Hysteretic Devices zur Erdbebenertüchtigung von Bauwerken demonstriert.
N2 - Main topic is the development of variance–reducing Monte Carlo methods, for the purpose of reliability analyses of engineering structures with nonlinear behaviour. Ch. 2 is a literature survey on variance-reducing Monte Carlo methods. The Spectral Representation of a scalar, stationary Gaussian process is derived in ch. 3. On this basis, two popular simulation methods are discussed. The variance-reducing simulation concept developed in ch. 4 is based on the Spectral Representation. After a first pilot simulation, the frequencies are selected for introduction of amplitudes as random variables. In addition, the parameters of the amplitudes are adapted. This is the basis for the second simulation following the Importance Sampling principle. This simulation concept is utilized for reliability analysis of a bridge subjected to earthquake excitation in ch. 5. The bridge is equipped with Hysteretic Devices for dissipation of energy. The example demonstrates, on one hand, the accuracy and efficiency of the developed simulation method. On the other hand, the effectiveness of Hysteretic Devices for earthquake protection of building structures becomes evident.
KW - Baukonstruktion
KW - Dynamische Belastung
KW - Zuverlässigkeit
KW - Sicherheitstheorie
KW - Erdbeben
KW - Probabilistik
KW - Brücke
KW - Monte-Carlo Simulation
KW - reliability assessment
KW - earthquake
KW - probabilistics
KW - bridge
KW - Monte Carlo simulation
Y1 - 1999
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20040205-215
ER -