TY - THES A1 - Kavrakov, Igor T1 - Structural Optimization of Composite Cross-Sections and Elements using Energy Methods N2 - Structural optimization has gained considerable attention in the design of structural engineering structures, especially in the preliminary phase. This study introduces an unconventional approach for structural optimization by utilizing the Energy method with Integral Material Behavior (EIM), based on the Lagrange’s principle of minimum potential energy. An automated two-level optimization search process is proposed, which integrates the EIM, as an alternative method for nonlinear structural analysis, and the bilevel optimization. The proposed procedure secures the equilibrium through minimizing the potential energy on one level, and on a higher level, a design objective function. For this, the most robust strategy of bilevel optimization, the nested method is used. The function of the potential energy is investigated along with its instabilities for physical nonlinear analysis through principle examples, by which the advantages and limitations using this method are reviewed. Furthermore, optimization algorithms are discussed. A numerical fully functional code is developed for nonlinear cross section, element and 2D frame analysis, utilizing different finite elements and is verified against existing EIM programs. As a proof of concept, the method is applied on selected examples using this code on cross section and element level. For the former one a comparison is made with standard procedure, by employing the equilibrium equations within the constrains. The validation of the element level was proven by a theoretical solution of an arch bridge and finally, a truss bridge is optimized. Most of the principle examples are chosen to be adequate for the everyday engineering practice, to demonstrate the effectiveness of the proposed method. This study implies that with further development, this method could become just as competitive as the conventional structural optimization techniques using the Finite Element Method. KW - Strukturoptimierung Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20190815-39593 ER - TY - THES A1 - Fröhlich, Jan T1 - On systematic approaches for interpreted information transfer of inspection data from bridge models to structural analysis N2 - In conjunction with the improved methods of monitoring damage and degradation processes, the interest in reliability assessment of reinforced concrete bridges is increasing in recent years. Automated imagebased inspections of the structural surface provide valuable data to extract quantitative information about deteriorations, such as crack patterns. However, the knowledge gain results from processing this information in a structural context, i.e. relating the damage artifacts to building components. This way, transformation to structural analysis is enabled. This approach sets two further requirements: availability of structural bridge information and a standardized storage for interoperability with subsequent analysis tools. Since the involved large datasets are only efficiently processed in an automated manner, the implementation of the complete workflow from damage and building data to structural analysis is targeted in this work. First, domain concepts are derived from the back-end tasks: structural analysis, damage modeling, and life-cycle assessment. The common interoperability format, the Industry Foundation Class (IFC), and processes in these domains are further assessed. The need for usercontrolled interpretation steps is identified and the developed prototype thus allows interaction at subsequent model stages. The latter has the advantage that interpretation steps can be individually separated into either a structural analysis or a damage information model or a combination of both. This approach to damage information processing from the perspective of structural analysis is then validated in different case studies. KW - Brückenbau KW - Strukturanalyse KW - Schadensanalyse KW - BIM KW - IFC KW - bridge inspection KW - damage information model KW - structural analysis KW - IFC KW - BIM Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20200416-41310 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 -