Parameter Study on Weight Minimization of Network Arch Bridges

The article concerns optimization of network arch bridges. This is challenging optimization problem involving even for conventional scheme of network arch bridge the identification of some topological parameters as well as shape configurations and all sizing parameters of structural members, seeking the minimum weight. Optimal bridge scheme is sought tuning a large set of design parameters of diverse character: the type of hanger arrangement, the number of hangers, their inclination angles and placement distances, the arch shape and rise, etc. Mathematically, the optimization of the bridge scheme is a mixed-integer constrained global optimization problem solved employing stochastic evolutionary algorithm. Plane heavy/moderate/and light-deck bridges of 18, 30, 42 and 54 m spans were optimized using proposed optimization technique. The decisive design parameters and their promising ranges were revealed. Also, the influence of some simplifications is shown: changing the arch shape from elliptical to circular, placing the hangers at equal distances, etc

Genetic algorithm based optimum design of prestressed concrete beam

ABSTRACT Design of prestressed concrete (PSC) beam involves many design variables. Simultaneously handling many design variables computationally expensive and in most cases finds relative optima. An efficient optimization technique, Genetic Algorithm (GA) is well suited for solving such problems and they can find global optimum solution. In the present paper six design variables are considered for optimizing the cost of simply supported prestressed concrete beam with all practical constraints. Since absolute cost of materials changes from time to time, total cost of the beam is expressed in terms of cost ratio. Parametric study has been done to observe the effect of size of population, number of generation, intensity of live load, cable profile and various practical beam lengths. Finally data base is prepared for various practical span lengths. Keyword: Genetic algorithm, cost ratio, prestressed concrete beam. Nomenclature P = Prestrssed force e= eccentricity B = beam width D = depth of beam Dc = diameter of the cable Aco = Area of the concrete ρco = density of concrete Cr co = cost ratio of the concrete ft = stress in top fiber ftt = permissible stress in tension at transfer Mg = moment due to dead load Zt = section modulus at top fb= stresses at bottom ftw = permissible tensile stress in concrete under working load η= prestress loss ratio Mq = moment due to live load Zb = section modulus at bottom W = UDL on beam E = young's modulus I = moment of inertia finf = minimum required prestress at the bottom fiber fsup = maximum tensile prestress at the top fibe

Shape optimisation of concrete open spandrel arch bridges

U ovom se radu analizira lučni most s otvorenim nadlučnim sklopom. Računalni kod je izveden za izradu modela na temelju geometrijskih podataka, a radi rješavanja problema optimalizacije. U ovom se radu provodi postupak optimalnog projektiranja, a ukupan obujam materijala ugrađenog u donji ustroj mosta usvaja se kao objektivna funkcija. Donji ustroj sadrži stup i armiranobetonski luk. Na kraju je proveden i postupak optimalizacije pomoću algoritma za istovremeno stohastičko predviđanje poremećaja.An open spandrel arch bridge is analysed in this paper. A computer code is written to create a model from geometrical data, so as to solve the optimisation problem. An optimum design procedure is conducted in the paper, and the total material volume of the bridge substructure is adopted as an objective function. The substructure includes the column and the reinforced-concrete arch. Finally, the optimization technique is implemented using the Simultaneous Perturbation Stochastic Approximation algorithm

Multivariate correspondence analysis in optimization studies of concrete bridges

[EN] The socio-cultural situation in which we find ourselves today, with limited budgets, greater awareness of the environment and high levels of gas emissions into the atmosphere, makes the future in general and the construction of structures in particularly aimed at finding designs that are more efficient. Since the 60s of last century to the present, several research groups spread across the five continents have tried to carry out optimization studies of concrete bridges, either the bridge in general and some of its elements in particular, publishing articles in scientific journals world-class. The featured paper extracts some qualitative variables defined and parameterized by reading that articles published over the years and it makes a simple multivariate correspondence analysis (SMCA). A sample of 93 articles has been analyzed and seven variables has been extracted from its. The two overall objectives are to determine whether the dependency relationships between different categories that the variables can take are statistically significant and to define possible new lines of research. Therefore, SMCA is divided into 10 pairs of variables namely ten independent studies. The software used has been IBM SPSS Statistics 21. The results show that the type of optimization problem resolution are related to the development of technology and computers, that genetic algorithms are related with maintenance phase, or that the optimization design of I-beam bridges is related with prestressed concrete among other. Finally, the thesis concludes that the optimization concrete bridge in construction phases or with special type of concrete could be new lines of research.Este estudio ha sido financiado por el Ministerio Español de Economía y Competitividad y fondos FEDER (proyecto de investigación BIA2014-56574-R)Yepes, V.; Marmaneu, A.; Gonzalez Vidosa, F.; Martí Albiñana, JV. (2017). Multivariate correspondence analysis in optimization studies of concrete bridges. International Center for Numerical Methods in Engineering (CIMNE). 1289-1306. http://hdl.handle.net/10251/180310S1289130

Aplicabilidad del análisis multivariante a las técnicas de optimización de los puentes de hormigón

[EN] The future of building structures in general and bridges in particular, for its costs, its high consumption of natural resources and pollution associated with such activity, is aimed at seeking greater efficiency in all its phases: design, construction and maintenance. An optimal solution will generate a solution with minimal costs, higher quality and more sustainable throughout the life of the structure. This increases the interest in the study of techniques to achieve this objective. In this sense, numerous investigations have been developed over the past 50 years, reflected in scientific articles in leading international journals, conferences and presentations for various doctoral theses. This final master thesis aims to analyze the evolution of research carried out over period named in the preceding paragraph, to establish relationships between what has been done in the past, what is doing in the present and future fields studies[ES] El futuro de la construcción de estructuras en general y de los puentes en particular, por sus costes, su elevado consumo de recursos naturales y la contaminación asociada a dicha actividad, está encaminado a la búsqueda de una mayor eficiencia en todas sus fases: diseño, construcción y mantenimiento. Una solución óptima será la que genere una solución con los mínimos costes, mayor calidad y más sostenible, en toda la vida útil de la estructura. Esto hace que aumente el interés en el estudio de técnicas para conseguir dicho objetivo. En este sentido, se han desarrollado numerosa investigaciones a lo largo de los últimos 50 años, plasmadas en artículos científicos en revistas de primer nivel internacional, en presentaciones para congresos y diversas tesis doctorales. La presente tesis final de máster pretende analizar la evolución de las investigaciones llevadas a cabo a lo largo del periodo nombrado en el párrafo anterior para poder establecer relaciones entre lo realizado en el pasado, los campos abiertos en el presente y hacia donde pueden ir los futuros estudios.Marmaneu Menero, A. (2016). Aplicabilidad del análisis multivariante a las técnicas de optimización de los puentes de hormigón. http://hdl.handle.net/10251/68969TFG

Analysis of design variables of prestressed concrete structures using optimization algorithms

V posledních letech je stále více kladen důraz na úspory a ekologická hlediska ve stavebnictví. Celkové množství vyprodukovaného betonu na zemi je obrovské (odhadem 1010 tun za rok). Možnost snížení jeho výroby pouze o několik procent může přinést významné materiálové úspory, redukci výdajů na přepravu a s tím souvisejících nákladů. Mezi další aspekty je možné zařadit omezení produkce CO2 a jiných škodlivin. Z těchto důvodů se jeví optimalizační analýza návrhových parametrů betonových konstrukcí jako velmi důležitá. Obecně lze definovat optimalizaci jako nalezení nejlepšího řešení pro danou úlohu. Optimalizační úlohy jsou definovány pro různá odvětví a spojuje je hledání minima nebo maxima cílové funkce. Je známo, že matematické metody a algoritmy umožňující nalezení optimálního tvaru nebo parametrů konstrukce, jsou již řadu let používány ve strojírenství. Každodenní aplikace ve stavebnictví je však doslova výjimečná. Návrhem stavební konstrukce pomocí optimalizačních algoritmů se zabývají pouze práce na vědecké úrovni. Nalezení optimálního tvaru konstrukce je obvykle otázkou zkušeností a znalostí projektanta, který návrh následně ověří svým výpočtem. Existuje mnoho důvodů, proč nejsou tyto algoritmy používány v běžné praxi. Patří mezi ně zejména absence uživatelsky přístupného a srozumitelného programu, který by napomáhal zoptimalizovat konstrukci v relativně krátkém čase, a také složitost optimalizační úlohy. Dalším imitujícím faktorem je skutečnost, kdy stavební konstrukce jsou vystaveny mnoha omezujícím podmínkám požadovaných normou. A v neposlední řadě pak změna návrhových parametrů budov, mostů či speciálních typů konstrukcí nevykazuje pravidelnou odezvu. Výše uvedená problematika je náplní předložené disertační práce.During recent years more and more emphasis has been put on saving and ecological aspects of the civil engineering industry. As the total volume of concrete being produced on our planet is immense (ca 1010 tons per year), the possibility of decreasing it by even a small percentage can bring large savings in material costs, transport and other costs and reduction of CO2 production and other pollution. Therefore, optimal analysis of design variables of concrete structures appears to be of high importance. Optimization is finding the best solution to a given problem. Many disciplines define different optimization problems and it is typically the minimum or maximum value of the objective function that is searched. It is known that mathematical procedures and algorithms to find an optimal structural design are used in practice in mechanical engineering, but the use of these tools in civil engineering is rather exceptional. Generally, scientific works deal with the optimal design of structures only. Finding of an optimal shape and dimensions is usually a question of the engineer’s experience and good “guess”, which is then verified by calculation. There are many reasons explaining why optimization in common practise is used only occasionally. One of them is the absence of proper user friendly software tools which could help within relatively short time available for structural design. Another reason is the complexity of optimization tasks as well as a lot of constraints in civil engineering design codes. Last but not least, the change of design variables of buildings, bridges and structures of special types do not express regular response. This issue is discussed in the submitted work.