No description available.

Interruption of railway traffic creates important financial losses for the transportation utilities and society at large. At this moment, to limit this impact, the CN uses emergency girders stored around their territory to decrease the time to transport the materials to the site. However, this method is difficult to put in place and bypass of the traffic is not possible everywhere. The development of a portable railway bridge is interesting for this purpose. This structure has to be transported, erected and in services within 48h. This type of bridge should also be adjustable in length to allow reusing of the existing bearings, piers and abutments (5 to 28m of span). Between the steel superstructure possibilities, three solutions have been chosen: (a) plate girder, (b) through girder and (c) through truss. The geometry and the construction method are the particularities to consider. After those conceptions, the three alternatives have been analyzed as a function of many criteria. The number of bolts, the quantity of material and the dimension of the prefabricated sections were considered to determine the best solution for this kind of utilization.

An investigation was performed for live load forces applied to soil-steel structures under shallow backfill depths, specifically a long span deeply corrugated box culvert. The work was also relevant to other types of flexible buried structures and loading scenarios. The investigation involved the application of both a robust experimental testing process and the development of 3-D finite element models. Full scale live load tests, performed in Dorchester NB, were executed to obtain a large sample of experimental data. The testing program was designed specifically to fully characterize the structural response of a long span box culvert to CHBDC design truck live loads. The program included live load testing at six different backfill depths with 21 unique truck positions per lift, with instrumentation at four separate rings. The experimental data was used to assess and calibrate the finite element models being developed to predict structural effects. The finite element software package ADINA was used to model the test structure in 3-D. The basics of model development, such as element types, boundary conditions, loads, and other analysis options were discussed. An orthotropic shell modeling approach to accurately describe the corrugated plate properties was developed. A number of soil constitutive models, both linear and nonlinear, were examined and evaluated. The data obtained from experimental testing was compared to the results obtained by the finite element modeling and the various soil models were evaluated. A parametric study was performed examining the sensitivity of modeling parameters. The impact of various assumptions made regarding the model was quantitatively established. The thesis provided guidance on the 3-D modeling of soil-steel structures allowing future researchers to study the factors which were significant to their design and field applications.

An explosion is characterized as a sudden release of large energy over a very short duration. As the blast wave travels parallel to a surface, it creates a side-on pressure and when it hits a surface perpendicularly or at an angle, it creates a reflected pressure. Side-on pressure and reflected pressure are much higher than service loads for the structure. Thus, when a blast happens near a building that is not designed to withstand blast loads, it can cause catastrophic damage. The objective of this study is to present a formulation for the design optimization of framed steel structures subjected to blast loads. Also, a formulation is presented for the design optimization of structures that can withstand some possible damage due to blast loads. To this end, an optimization procedure that includes definitions of design variables, cost function, constraints, and structural analyses is discussed. The design variables for beams and columns are the discrete values of the W-shapes selected from American Institute of Steel Construction (AISC) tables. The optimization problem is to minimize the total structural weight subjected to AISC strength requirements and blast design displacement constraints. Linear static, linear dynamic, and nonlinear dynamic analyses are incorporated in the optimization process and optimum designs are compared. Due to design variables and some constraints discontinuity, gradient-based optimization algorithms cannot be used to solve the optimization problem. Therefore, metaheuristic algorithms are used that require only simulation results to solve problems with discrete variables and non-differentiable functions. Since the number of simulations and robustness to obtain good designs are important for the class of problems discussed in this research, a new hybrid optimization algorithm based on Harmony Search (HS) and Colliding Bodies Optimization (CBO) is developed and examined. The algorithm is named Hybrid Harmony Search - Colliding Bodies Optimization (HHC). Also, a novel design domain reduction technique is incorporated in HHC. Some benchmark discrete variable structural design problems are used to evaluate HHC. In comparison with some popular metaheuristic optimization algorithms, HHC is shown to be robust, effective, and needs fewer structural analyses to obtain the best designs. Depending on the size of the structure to be designed, optimization of structures that require linear or nonlinear dynamic analyses using metaheuristic algorithms can be computationally expensive because these types of algorithms need large number of simulations to reach good designs. Equivalent Static Loads (ESL) approach, which has been used for optimization of structural systems subjected to dynamic loads using gradient-based algorithms, is examined for optimization of structures that have discrete design variables using metaheuristic algorithms. The proposed approach is named global optimization with equivalent static loads (GOESL). Solution of four numerical examples shows that GOESL can drastically reduce the number of dynamic analyses needed to reach the best design compared to an algorithm without the ESL approach. However, the ESL step alone cannot converge to the best design for the current formulation, even with many ESL cycles. Therefore, after a few ESL cycles, the procedure may switch to the original algorithm without the ESL cycles to improve designs further. HHC and GOESL are used to solve three-dimensional framed steel structures subjected to blast loads with linear and nonlinear dynamic analyses as separate solution cases. The source of the blast loads is a car carrying 250 lbs of Trinitrotoluene (TNT) with 50 ft standoff distance from the front face of a 4-bay x 4-bay x 3-story building. Optimum designs of the structure to withstand blast loads show that penalty on the optimum structural weight is substantial when linear dynamic analysis is used. With nonlinear dynamic analysis, the penalty on the structural weight is substantially reduced. When the stiffness of the walls is included in the analysis model, there is very little penalty on the optimum structural weight with linear or nonlinear dynamic analysis models. The best designs obtained with the linear and nonlinear dynamic analysis models are checked for some possible damages due to a blast. Two types of damage conditions are defined: (i) complete removal of some key members from the analysis model, and (ii) reduction of stiffness of some members. It is shown that the best designs using linear or nonlinear dynamic analyses can withstand all damage conditions. Thus, resilience of the designs to withstand blast loads is observed.

No description available.

No description available.

The Thirteenth East Asia-Pacific Conference on Structural Engineering and Construction, September 11-13, 2013, Sapporo, Japan (EASEC-13)

As part of the water resources policy of the state of CearÃ, in Northeast Brazil, COGERH, as an operational instrument, has among its tasks the distribution of bulk water for various uses. Among the water systems that COGERH operates are the pumping stations, which are responsible for supplying water for cities, industries, irrigation, etc. It is vital that these structures operate satisfactorily and efficiently. Among the many devices that make up the pumping stations are the semisubmersible floating metal chambers that are located on the water surface of the reservoirs, providing support to the pumps and motors such that they can be set and operated reliably and efficiently. However, these structures are made from steel and therefore are subject to severe corrosion processes, making it necessary for the painting of the submerged areas to ensure the necessary protection to avoid oxidation of them. As painting alone is not a process that ensures 100% efficiency in terms of coating and has a relatively short lifespan, complementary processes are necessary to ensure safe protection against corrosion. Among these processes is the Cathodic Protection, which ensures that, while a difference in electrochemical potential is being generated between the structure to be protected and a sacrificial anode, the structure will not undergo corrosion processes. For this study, it has been designed and installed an Impressed Current Cathodic Protection System with a potential ON of protection of -2.67 Volts (DC) for the Pumping Station known as "EB GaviÃoâ chosen due to its strategic importance within the state infrastructure of water resources, responsible for supplying water for major cities and industries. Keywords : / Dentro da polÃtica dos recursos hÃdricos do estado do CearÃ, no Nordeste do Brasil, a COGERH, como instrumento operacional, tem entre suas atribuiÃÃes a distribuiÃÃo de Ãgua bruta para usos diversos. Dentre os sistemas que a COGERH operacionaliza estÃo as estaÃÃes de bombeamento, as quais sÃo responsÃveis por abastecer cidades, indÃstrias, irrigantes, etc. à fundamental que tais estruturas operem de forma satisfatÃria e eficiente. Dentre os muitos equipamentos que compÃem as estaÃÃes de bombeamento estÃo Ãs cÃmaras metÃlicas flutuantes emisubmersÃveis que se localizam na superfÃcie de Ãgua dos reservatÃrios, dando sustentaÃÃo para que as bombas e motores possam ser fixados e operados de forma confiÃvel e eficiente. No entanto estas estruturas, por serem de aÃo, estÃo sujeitas a processos de corrosÃo severos, fazendo-se necessÃrio que a pintura das Ãreas submersas assegurem a proteÃÃo necessÃria para que nÃo haja oxidaÃÃo das mesmas. Como a pintura nÃo à um processo que garante uma eficiÃncia de 100% e termos de revestimento e tem uma vida Ãtil relativamente curta, fazem-se necessÃrios processos complementares para uma segura proteÃÃo anti-corrosÃo. Dentre esses processos està a ProteÃÃo CatÃdica que assegura que enquanto estiver sendo gerada uma âdiferenÃa de potencial eletroquÃmicoâ entre a estrutura a ser protegida e um anodo de sacrifÃcio a estrutura nÃo sofrerà severos processos de corrosÃo. Neste estudo foi dimensionado e instalado um Sistema de ProteÃÃo CatÃdica por Corrente Impressa assegurando um potencial ON de proteÃÃo de -2,67 Vcc para a estaÃÃo de bombeamento denominada âEB GaviÃoâ pela importÃncia estratÃgica que ocupa dentro da infraestrutura estadual de recursos hÃdricos, fazendo parte de sistema responsÃvel pelo abastecimento de importantes cidades e indÃstrias.

The diploma thesis is focused on the assessment and verification dimensions of the existing supporting steel structure for the K5 boiler in the locality of Olomouc. The ground dimensions of the existing main supporting structure are 24.4 x 12.2 m. The clear construction height is approx. 44 m. The main supporting columns are made of welded box cross sections. The spacing of the individual cross-links is 7.6-8.9 m. The structural stiffness of the structure is secured by transverse and longitudinal bracing. Stainless steel S235 and S355 are used as the main material of the supporting elements. The design has been assessed according to valid EN ISO standards. Part of the thesis is a technical report, a static calculation containing the assessment of the main structural elements of the structure and joints and the drawing documentation.

The subject of the master thesis is the design and assessment of the supporting roof steel structure on the building, which will be used for various sports events in Znojmo. The building has a rectangular floor plan with dimensions of 50 x 60 m. The height at the top is 15 m. The trusses are articulated on concrete columns. Structure stability ensures system of bracings. The work contains a static calculation of the main load-bearing elements, including the relevant joints. The roof and cladding consist of sandwich panels.