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Tensegrity structures consist of isolated compression members (rigid bars) suspended by a continuous network of tension members (cables). Tensegrity structures can be used as variable geometry truss (VGT) mechanisms by actuating links to change their length. This paper will present a new method of position finding for tensegrity structures that can be used for actuation as VGT mechanisms. Tensegrity structures are difficult to understand and mathematically model. This difficulty is primarily because tensegrity structures only exist in specific stable tensegrity positions. Previous work has focused on analysis based on statics, dynamics, and virtual work approaches. This work considers tensegrity structures from a kinematic viewpoint. The kinematic approach leads to a better understanding of the conditions under which tensegrity structures exist in the stable positions. The primary understanding that comes from this kinematic analysis is that stable positions for tensegrity structures exist only on the boundaries of nonassembly of the structure. This understanding also allows the tensegrity positions to be easily found. This paper presents a method of position finding based on kinematic constraints and applies that method to several example tensegrity structures. / Master of Science

In current bridge practice, all tension members in a truss bridge are identified as fracture critical members which implies that a collapse is expected to occur once a member of this type fails. However, there are several examples which show that bridges have remained standing and shown little distress even after a fracture critical member was completely damaged. Due to the high inspection cost for fracture critical members, it would be beneficial to remove fracture critical designation from some tension members. This could be achieved via considering system redundancy. Since there is no clear guidance in existing codified provisions for assessing system redundancy, this research is undertaken to develop simplified analysis techniques to evaluate system redundancy in truss bridges. The proposed system redundancy analysis in this research starts with the identification of the most critical main truss members whose failure may significantly affect the system redundancy. The system redundancy is then measured by the remaining load capacity of a damaged bridge after losing one of the critical members. The bridge load capacity is checked using 3D models with nonlinear features that can capture the progression of yielding and buckling in a bridge system. The modeling techniques are validated through the case studies of the I-35W Bridge and one test span of the Milton-Madison Bridge. Reasonable correlations are demonstrated between the models and the measured data for these two bridges both in an undamaged and in a damaged state. The feasibility of the proposed methodology for system redundancy evaluation is examined by applying the methodology blindly to two other simple truss bridges. The application shows that the proposed methodology can efficiently measure the system redundancy. To improve the system redundancy, this research also proposes sample retrofit strategies for the four example bridges. / Ph. D.

As the necessity of sustainable mobility rises, the demand to reduce the environmental impact of transporting mediums increases. The SUGAR Truss-Braced Wing (TBW) aircraft is a venture of Boeing, NASA and Virginia Tech for the N+3 generation of aircraft. These high-aspect-ratio aircraft are being designed with the aim to improve the structural and aerodynamic performance by implementing advanced technologies. Aerodynamics is a major factor influencing the performance of the aircraft, affecting the fuel consumption and emissions, especially due to drag. The multidisciplinary design optimization architecture for truss-braced-wing aircraft is dedicated to generate configurations with low fuel burn, maximum weight carrying capabilities and aircraft stability for long and medium range missions. The incorporation of flight dynamics at the conceptual design stage offers enhanced aerodynamic performance and wing flexibility for the aircraft. A robust flight dynamic system would need a detailed aerodynamic analysis of the aircraft with the focus on aeroelasticity. In this thesis, various aerodynamic coefficients and stability derivatives are investigated by applying Vortex-Lattice Method using OpenVSP, an open-source platform. The variation in aerodynamic parameters with changes in configurations and flow conditions are discussed as well. OpenVSP allows for study of these results with low computational expense. This will aid in efficient aerodynamic design and lay basis for flight dynamics analysis and its inclusion in the Multidisciplinary Design Analysis and Optimization (MDAO) framework. / Master of Science / The demand for sustainable mobility and green transportation is increasing. Reduction in the environmental impact of these mediums is the prime motivation for various research studies conducted in this domain. The SUGAR Truss-Braced Wing (TBW) aircraft configuration research, led by Boeing, NASA and Virginia Tech over the last two decades, aims at developing highly fuel-efficient next-generation aircraft. These high-aspect-ratio aircraft are being researched for improving the structural and aerodynamic performance by implementing advanced technologies. Aerodynamic performance of the aircraft influences the fuel consumption and emissions produced drastically. The current design optimization framework for the TBW aircraft focuses on development of these aircraft configurations with the goal to limit fuel burn and maximize payload carrying capability. Flight dynamics analysis can be significant to improve and obtain optimal solutions from the design process. Incorporation of flight dynamics at the conceptual design stage offers enhanced aerodynamic performance and wing flexibility for the next generation aircraft. Therefore, a detailed aerodynamic analysis of the aircraft would be needed to establish a systematic flight dynamics module. This thesis presents a new approach for formulating and analysing the aerodynamic coefficients and stability derivatives by implementing Vortex-Lattice Method available in the open-source software. This will further allow for inclusion of flight dynamics study of the new configurations for long and medium range missions within the existing framework.

Since the last century a lot of effort has been spent trying to analyze damage and crack evolution in solids. This field is of interest because of the many applications that require the study of the behavior of materials at the micro- or nanoscale, i.e. modeling of composites and advanced aerospace applications. Peridynamics is a recently developed theory that substitutes the differential equations that constitute classical continuum mechanics with integral equations. Since integral equations are valid at discontinuities and cracks, peridynamics is able to model fracture and damage in a more natural way, without having to work around mathematical singularities present in the classical continuum mechanics theory. The objective of the present work is to show how peridynamics can be implemented in finite element analysis (FEA) using a mesh of one-dimensional truss elements instead of 2-D surface elements. The truss elements can be taken as a representation of the bonds between molecules or particles in the body and their strength is found according to the physical properties of the material. The possibility implementing peridynamics in a finite element framework, the most used method for structural analysis, is critical for expanding the range of problems that can be analyzed, simplifying the verification of the code and for making fracture analysis computationally cheaper. The creation of an in-house code allows for easier modifications, customization and enrichment if more complex cases (such as multiscale modeling of composites or piezoresistive materials) are to be analyzed. The problems discussed in the present thesis involve plates with holes and inclusions subjected to tension. Displacement boundary conditions are applied in all cases. The results show good agreement with theory as well as with empirical observation. Stress concentrations reflect the behavior of materials in real life, cracks spontaneously initiate and debonding naturally happens at the right locations. Several examples clearly show this behavior and prove that peridynamics is a promising tool for stress and fracture analysis. / Master of Science

Yes / This paper proposes a new design concept for a steel truss-reinforced concrete box girder which incorporates a steel truss instead of longitudinal bars and stirrups. A comprehensive assessment of the flexural and shear behavior of the proposed steel truss-reinforced concrete box girders was conducted through the testing of twelve girders until failure. All test specimens had the same concrete depth and width of 400 mm and 300 mm, but the length of concrete in the shear and flexural specimens were 3300 mm and 3100 mm, respectively. Moreover, the reinforcing steel truss configuration and member sizes were different. The effects of the angle steel size of the lower chord, vertical webs spacing, shear span ratio and presence of diagonal webs on the cracking, yield and ultimate loads, crack patterns, failure modes, vertical load-deflection curves and strain distribution of these steel truss-reinforced concrete box girders were studied. The test results showed that the flexural capacity of the steel truss-reinforced concrete box girder increases with the increase of angle steel size of the lower chord. Moreover, the spacing of vertical webs and presence of diagonal webs have little effect on the flexural capacity of steel truss-reinforced concrete box girders tested. With the decrease of the shear span ratio and vertical webs spacing, the shear capacity of the steel truss-reinforced concrete box girder increases. Finally, simplified formulae for calculating the flexural and shear capacities of steel truss-reinforced concrete box girders were proposed, showing good agreement with the experimental results. / The full-text of this article will be released for public view at the end of the publisher embargo on 2 Oct 2024.

The subject of this master's thesis is a static and structural design of a Load-carrying steel structure of railway bridge with bottom steel deck of the span of 42 + 60 + 42 m over the Labe river in Děčín. A solid steel beam forms the main load-bearing structure of the bridge reinforced with truss-work. The truss-work is made up of an open top chord and diagonal strut without secondary vertical struts. The calculations were done in compliance with valid ČSN EN documents.

The subject of diploma thesis is design and static assessment of steel structure of multipurpose hall. Construction is located in the city Brno. The floor plan is rectangular with dimensions 60 x 80 m. Headroom of the structure is 12,5 m and total height is 16,5 m. A main frame is created of arch truss supported by column and truss structure on both sides. The main frames are joined by purlins. Final support structure was selected from two preliminary variants. For the selected variant was made static calculation of main bearing elements including joints and anchoring, technical report, drawings and bill of quantities.

Diploma thesis describes the design and assessment of the roof structure that covers the courtyard of office buildings. Structure has a regular floor plan and roof height is 15,0 m. The material if the structure is steel S355, bolts 8.8., steel of the pins is S355. Construction is located in Brno. Two options were produced and designed, evaluated according to the latest standards.