When a fire reaches the point of flashover the hot gases inside the burning room ignite resulting in furnace-like conditions. Thereafter, the building frame experiences temperatures sufficient to compromise its structural integrity. Physical and mathematical models help to predict when this will happen. This thesis looks at both the thermal and structural aspects of modelling a frame exposed to a post-flashover fire. The temperatures in the frame are calculated by solving a 2D heat conduction equation over the cross-section of each beam. The solution procedure uses the finite element method with automatic mesh generation/adaption based on the Delaunay triangulation process and the recovered heat flux. With the Euler-Bernoulli assumption that the cross-section of a beam remains plane and perpendicular to the neutral line and that strains are small, an error estimator, based on the work of Bank and Weiser [9], has been derived for finite element solutions to small-deformation, thermoelastic and thermoplastic frame problems. The estimator has been shown to be consistent for all finite element solutions and asymptotically exact when the solution involves appropriate higher degree polynomials. The asymptotic exactness is shown to be closely related to superconvergence properties of the approximate solution in these cases. Specifically, with coupled bending and compression, it is necessary to use quadratic approximations, instead of linear, for the compression and twisting terms to get a global O(h2) rate of convergence in the energy norm, some superconvergence properties and asymptotic exactness with the error estimator.

<p>Some products share one or two modules and while developing these products, structural optimization with stiffness as the objective function can be a useful tool. There might be no or very little CAD-data available in the pre-development phase and it is not certain that existing designs can be, or is desirable to use as a reference. The main objective of this thesis is to establish an accurate and fast-to-use methodology which can be utilized while developing new cars.</p><p>In this thesis, the Volvo products S40, V50 and C70 serve as a basis for this case study. All the models are beam structures and the masses of components are added as point and line masses. Several optimization analyses are performed on one or three products exposed to seven load cases. Additional analyses with shell elements, more simplified models and changed load case balance achieved by normalization of the different load case compliances are also studied to investigate how these factors influence the results.</p><p>Analyses show that front crash to a great extent dominates the results while normalization increases the influence of the remaining load cases. Since front crash is dominating and the front area is shared in all products, the performance is remarkably similar when three products are optimized compared to separate analyses of one product. Analysis of models without added point or line masses gives a result which greatly differs from previous results and therefore shows that added masses are required. The methodology is applicable to develop products and detect new load paths through the car.</p>

Some products share one or two modules and while developing these products, structural optimization with stiffness as the objective function can be a useful tool. There might be no or very little CAD-data available in the pre-development phase and it is not certain that existing designs can be, or is desirable to use as a reference. The main objective of this thesis is to establish an accurate and fast-to-use methodology which can be utilized while developing new cars. In this thesis, the Volvo products S40, V50 and C70 serve as a basis for this case study. All the models are beam structures and the masses of components are added as point and line masses. Several optimization analyses are performed on one or three products exposed to seven load cases. Additional analyses with shell elements, more simplified models and changed load case balance achieved by normalization of the different load case compliances are also studied to investigate how these factors influence the results. Analyses show that front crash to a great extent dominates the results while normalization increases the influence of the remaining load cases. Since front crash is dominating and the front area is shared in all products, the performance is remarkably similar when three products are optimized compared to separate analyses of one product. Analysis of models without added point or line masses gives a result which greatly differs from previous results and therefore shows that added masses are required. The methodology is applicable to develop products and detect new load paths through the car.

Subject of this master thesis is a flyover bridge over the road II/434 and flood-land. As a load-bearing construction is designed two-beam structure. Traffic loads on this structure are considered according to standard ČSN EN 1991-2. The structure design is based on resultant stressing according to standard ČSN EN 1992-2.

The master's thesis object is to design a road bridge over the Jihlava river. Three studies are proposed from which pre-stressed two-beam structure with three spans variant is chosen. A detailed structural analysis elaborated and the bridge is analysed according to ultimate limit state and serviceability limit state. Drawing documentation and visualisation were made. The structure design is based on the European standarts.

A series of composite beam models are constructed for efficient high-fidelity beam analysis based on the variational-asymptotic method (VAM). Without invoking any a priori kinematic assumptions, the original three-dimensional, geometrically nonlinear beam problem is rigorously split into a two-dimensional cross-sectional analysis and a one-dimensional global beam analysis, taking advantage of the geometric small parameter that is an inherent property of the structure. The thermal problem of composite beams is studied first. According to the quasisteady theory of thermoelasticity, two beam models are proposed: one for heat conduction analysis and the other for thermoelastic analysis. For heat conduction analysis, two different types of thermal loads are modeled: with and without prescribed temperatures over the crosssections. Then a thermoelastic beam model is constructed under the previously solved thermal field. This model is also extended for composite materials, which removed the restriction on temperature variations and added the dependence of material properties with respect to temperature based on Kovalenoko’s small-strain thermoelasticity theory. Next the VAM is applied to model the multiphysics behavior of beam structure. A multiphysics beam model is proposed to capture the piezoelectric, piezomagnetic, pyroelectric, pyromagnetic, and hygrothermal effects. For the zeroth-order approximation, the classical models are in the form of Euler-Bernoulli beam theory. In the refined theory, generalized Timoshenko models have been developed, including two transverse shear strain measures. In order to avoid ill-conditioned matrices, a scaling method for multiphysics modeling is also presented. Three-dimensional field quantities are recovered from the one-dimensional variables obtained from the global beam analysis. A number of numerical examples of different beams are given to demonstrate the application and accuracy of the present theory. Excellent agreements between the results obtained by the current models and those obtained by three-dimensional finite element analysis, analytical solutions, and those available in the literature can be observed for all the cross-sectional variables. The present beam theory has been implemented into the computer program VABS (Variational Asymptotic Beam Sectional Analysis).

The subject of this thesis was to design and assess the load-bearing structure of the grandstand roof at the sports stadium. The ground plan dimensions are 35x70 m. The object will be located in Moravské Budějovice. The construction is made of grade steel S355 and steel fasteners. Assessments were created for 2 variants. Variant A with truss, Variant B with plate girder. The truss variant, which is elaborated in more detail, was evaluated as more advantageous.