Conceptual design of long-span trusses using multi-stage heuristics

A hybrid method that addresses the design and optimization of long-span steel trusses is presented. By utilizing advancements in present day computing and biologically inspired analysis and design, an effort has been made to automate the process of evolving optimal trusses in an unstructured problem domain. Topology, geometry and sizing optimization of trusses are simultaneously addressed using a three stage methodology. Multi-objective genetic algorithms are used to optimize the member section sizes of truss topologies and geometries. Converting constraints into additional objectives provides a robust algorithm that results in improved convergence to the pareto-optimal set of solutions. In addition, the pareto-curve plotted based on how well the different objectives are satisfied helps in identifying the trade-offs that exist between these objectives, while also providing an efficient way to rank the population of solutions during the search process. A comparison study between multi-objective genetic algorithms, simulated annealing, and reactive taboo search is conducted to evaluate the efficiency of each method with relation to its overall performance, computational expense, sensitivity to initial parameter settings, and repeatability of finding near-global optimal designs. The benefit of using a three stage approach, and also implementing the entire model on parallel computers, is the high level of computational efficiency that is obtained for the entire process and the near-optimal solutions obtained. The overall efficiency and effectiveness of this method has been established by comparing the truss design results obtained using this method on bridge and roof truss benchmark problems with truss designs obtained by other researchers. One of the salient features of thisresearch is the large number of optimal trusses that are produced as the final result. The range of designs available provides the user with the flexibility to select the truss design that best matches their design requirements. By supporting human-computer interactions between these stages, the program also incorporates subjective aesthetic criteria, which assist in producing final designs in consonance with the user's requirements

Otimização de Coberturas em Aço de Edifícios Industriais

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Civil.O presente trabalho apresenta um procedimento de otimização para estruturas de coberturas em aço de edifícios industrias. A formulação baseia-se em determinar telhas, terças, tirantes, contraventamentos dos banzos inferiores e barras a serem utilizados no projeto, como também as coordenadas nodais e o espaçamento entre pórticos que minimizem a massa da cobertura, e por consequência, o consumo de aço. Para tanto, utiliza-se o algoritmo de otimização Search Group Algorithm (SGA), ou Algoritmo do Grupo de Busca, obedecendo-se os critérios das normas ABNT NBR6123 (1988) – Forças devidas ao vento em edificações e ABNT NBR8800 (2008) – Projeto de estruturas de aço e de estruturas mistas de aço e concreto de edifícios. Propõem-se dois problemas, nos quais primeiramente se busca a cobertura com menor massa por meio da otimização dimensional, em seguida pela otimização dimensional em conjunto com a geométrica, e por último pela otimização dimensional em conjunto com a geométrica considerando o número de pórticos como variável. Os resultados mostraram a importância de se considerar o número de pórticos como uma variável de projeto, assim como o melhor espaçamento entre terças, devido a sua influência nas telhas e estas na massa final da cobertura.This paper presents an optimization procedure of steel roofing structures for industrial buildings. The formulation is based on determining tiles, purlins, risers, bracing of the bottom chord and bars to be used in the design, as well as nodal coordinates and the spacing between frames to minimize the roofing mass, and therefore decreasing steel consumption. To do so, it uses the optimization algorithm named Search Group Algorithm (SGA), and follows the criteria of ABNT NBR6123 (1988) - Building construction - Bases for design of structures - Wind loads - Procedure and ABNT NBR8800 (2008) - Design of steel and composite structures for buildings. It proposes two problems, in which firstly seeks to the roofing a smaller mass through size optimization, then through size optimization together with shape optimization and at last through size optimization together with shape optimization considering the number of frames as a variable. The results showed the importance of considering the number of frames as a design variable, as well as the best spacing between purlins due to its influence on tiles and these on the roofing structures final mass

Optimal design of vehicle with internal space frame structure subjected to high impact load

Armored military vehicles are heavily used in modern warfare. These vehicles are subjected to lethal attacks from projectiles and land mines. The shocks from these attacks may risk the safety of the occupants and damage the electronic instruments within the vehicle. Extensive research on the analysis and reduction of shocks on civilian vehicles has been performed. Fewer researchers addressed these problems in the case of military vehicles. Space frames are usually used to enhance structural strength of the vehicle while reducing its overall weight. These frames comprise of beams connected together at joints. Recently, space frames were incorporated in military vehicles. In this dissertation, a finite element model of a military vehicle with an internal space frame is developed. The space frame is composed of hollow square cross-section bars and angle sections. These frame members are bolted to the joints. The space frame is enclosed by uniform-thickness armor, except at the turret. The vehicle is subjected to high impact load that simulates a projectile hit. The vehicle design is optimized to reduce the overall mass, and shock at critical locations of the space frame. A lab-scale space frame structure derived from the military vehicle space frame is designed and built. The lab-scale space frame is subjected to non-destructive shock propagation tests. A finite element model of this structure is developed with the objective of matching the experimental results

History of Construction Cultures Volume 1

History of Construction Cultures Volume 1 contains papers presented at the 7ICCH – Seventh International Congress on Construction History, held at the Lisbon School of Architecture, Portugal, from 12 to 16 July, 2021. The conference has been organized by the Lisbon School of Architecture (FAUL), NOVA School of Social Sciences and Humanities, the Portuguese Society for Construction History Studies and the University of the Azores. The contributions cover the wide interdisciplinary spectrum of Construction History and consist on the most recent advances in theory and practical case studies analysis, following themes such as: - epistemological issues; - building actors; - building materials; - building machines, tools and equipment; - construction processes; - building services and techniques ; -structural theory and analysis ; - political, social and economic aspects; - knowledge transfer and cultural translation of construction cultures. Furthermore, papers presented at thematic sessions aim at covering important problematics, historical periods and different regions of the globe, opening new directions for Construction History research. We are what we build and how we build; thus, the study of Construction History is now more than ever at the centre of current debates as to the shape of a sustainable future for humankind. Therefore, History of Construction Cultures is a critical and indispensable work to expand our understanding of the ways in which everyday building activities have been perceived and experienced in different cultures, from ancient times to our century and all over the world

Proactive-reactive, robust scheduling and capacity planning of deconstruction projects under uncertainty

A project planning and decision support model is developed and applied to identify and reduce risk and uncertainty in deconstruction project planning. It allows calculating building inventories based on sensor information and construction standards and it computes robust project plans for different scenarios with multiple modes, constrained renewable resources and locations. A reactive and flexible planning element is proposed in the case of schedule infeasibility during project execution

A study of illegal housing of Lisbon built in 1974 to 1984 : from description to computation

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Architecture, 2005.Vita.Includes bibliographical references (leaves [123]-129).A morphological description of illegal housing built by homeowners in the Metropolitan Area of Lisbon between 1974 and 1984 is presented. This description is based on a parametric set grammar that attempts to formulate both topological and geometric aspects of the house. Therefore, the grammar is made of shapes, symbols, and their relations in space. The architectural description herein considers aspects of structure, function and use. The main characteristic of this illegal housing is that design and building are here the inhabitant's responsibility. These houses are usually seen by society as a chaotic and ugly constituent of the built environment. Yet for the users these are dream houses, shaped with symbolic references that helped assure each homeowner a good assimilation into the big city. Three basic goals led to this study: first, to search for a better understanding of these dream houses despite their many contradictions, second, to find a formal representation despite the chaotic appearance and genesis of these illegal houses, and third, to contribute to the formalizing of a computer implementation that could help to prevent further echoes of this scenario.(cont.) As analyses and synthesis may not have the same type of description, relating the substance of representation, both inside or outside computation, and the processes that should work with that representation became an important issue for the work herein. The result creates a speculative framework which, it is hoped, will help to define a computer representation of an architectural chain that can deal with the complexity of scaling house representation from abstract to concrete. Therefore, some considerations are made regarding shape grammars and their ancillary grammars, as well as the heuristic processes that may operate with those grammars.by Luís António dos Santos Romão.Ph.D

Topology Optimization of Engine Exhaust-Washed Structures

Aircraft structure subjected to elevated temperature and acoustic loading present a challenging design environment. Thermal stress in a structural component has typically been alleviated by allowing thermal expansion. However, very little work has been done which directly addresses the situation where such a prescription is not possible. When a structural component has failed due to thermally-induced tensile stresses, the answer to the question of how best to stiffen the structure is far from trivial. In this work, we demonstrate that conventional stiffening techniques, for example, those which add material to the thickness of a failing panel, may actually increase the rate of damage as well as increasing load into sub- and surrounding structure. The typical compliance minimization topology optimization formulation is applied to a thermally-loaded panel resulting in extremely non-optimal configurations. To generate successful thermal stress designs where the objectives are to lower the tensile stresses while simultaneously limiting the amount of additional load into sub- and surrounding structures, a well-known characteristic of topology optimization for a single-load case mechanical loading is exploited which by construction limits additional load into surrounding structure. Acoustic loading is also a major concern as exhaust gases with random frequency content impinge on aircraft structure in the vicinity of the engines. An evolutionary structural optimization algorithm is developed which addresses both the maximum von-Mises stress and minimum natural frequency for a generic thermal protection system. The similarities between the two approaches are demonstrated

Proactive-reactive, robust scheduling and capacity planning of deconstruction projects under uncertainty

A project planning and decision support model is developed and applied to identify and reduce risk and uncertainty in deconstruction project planning. It allows calculating building inventories based on sensor information and construction standards and it computes robust project plans for different scenarios with multiple modes, constrained renewable resources and locations. A reactive and flexible planning element is proposed in the case of schedule infeasibility during project execution

Travels in lounge space : placing the contemporary British motorway service area

This thesis reads contemporary British motorway service areas as questions of place, and as instances of what I call ‘lounge space’, a space of transient consumption that conceals the power of the host. Motorways and service areas are sites where clear boundaries have been asserted, materially as well as theoretically, between local and national, traditional and modern, country and city, place and ‘non-place’. Through close readings of service area forms, details and materials in context, this thesis shows how such absolute distinctions cannot be maintained. Rather than instances of ‘non-place’ – Marc Augé’s term for spaces lacking social relations, history or identity – service areas show place as process: as never absolutely fixed and always dependent on interrelated material, socio-cultural and historical contexts. This is not to dissolve the differences between places, but to show how they are contested and the power relations involved. The thesis thus explores a notion of place informed by what Jacques Derrida calls ‘iterability’, a logic of irreducible contamination, of repetition with difference. Chapter 1 considers two typical recent service areas, Hopwood Park and Donington Park. It shows how boundaries of place are dissimulated and yet tightly policed, how allusions to ‘public’ space also recall the ‘private’ space of the home, and how an illusion of unlimited hospitality conceals the power of the host. By comparison, ‘independent’ operator Westmorland, the focus of Chapter 2, appears to be an exception. On one level, the company’s Tebay Services reclaim the roadside for the locality; on another, however, the sites, and the region they represent, become caught up in the cultures, forces and economies they claim to resist. Westmorland the company is conflated with Westmorland the place. As this ‘natural’ host offers an idyllic Lakeland refigured for the outsider’s consumption, it contests how and by whom that place is to be consumed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design optimization of N-shaped roof trusses using reactive taboo search

Design optimization of a class of plane trusses called the N-shaped truss (NST) is addressed. The parametric model of NST presented is intended for real-world application, avoiding simplifications of the design details that compromise the applicability. The model, which includes 27 discrete variables concerning topology, configuration and sizing of the truss, presents a challenging optimization problem. Aspects of such challenge include large search space dimensionality, absence of a closed-form objective function (OF) and constraints, multimodal objective function and costly CPU time per objective function evaluation. Three implementations of general-purpose genetic algorithms (GAs) are tested for this problem, along with a version of taboo search called reactive taboo search (RTS). In this study, the raw version of RTS exhibited better performance than the tested versions of GA but lacks some of the GA capabilities to span the search space. A modification of RTS that uses a population-based exploitation of the search history is proposed. The optimization results show that the introduced modification can further improve the performance of RTS.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90876/1/Saitou32.pd