Structural Design

Özet
Matematiğin mimarlık dahil olmak üzere farklı disiplinlerle girdiği sıkı ilişki ve teknolojinin gün geçtikçe gelişmesiyle kullanım alanı artan bilgisayar destekli tasarım teknolojisi sayesinde tasarım sürecinde farklı matematiksel modellerin kullanılması mümkün olmuştur. Matematiksel modellerle strüktür tasarımı, geometri ve malzeme parametrelerini ön plana çıkarmıştır. 
Karmaşıklık kuramının sistemdeki dinamiklerin modellenmesi açısından strüktür tasarımındaki rolü önemlidir. Birbirinden farklı birçok parametrenin olması ve bunlar arasındaki ilişkilerin keşif süreci taşıyıcı sistemi tasarlanabilir bir sistem yapmıştır.  Geometri, bu sistemin formunu oluşturur ve ilk dikkat çeken parametredir. Yaratılan her form bir geometri içerir ve formun ayakta durabilmesi için de strüktür tasarımına ihtiyaç vardır. Mimarlıkta geometriyle birlikte malzeme, tasarımın dokusunun, biçiminin ve binanın görünümünün oluşmasında temel bileşenlerdendir.
Strüktür tasarımında en temel yöntem olan sonlu elemanlar analizi ışığında, arup optimizeri, dinamik rahatlama, evrimsel şekil optimizeri ve evrimsel strüktür optimizeri incelenmiştir. Bu analizler sonucu ortaya çıkan zincir eğrisi, bükülme, minimal yüzey ve nurbs modelleri araştırılmıştır. Arup optimizeri, tüm sistemde kendi kendini organize etmesini sağlayacak en uygun tekrar elemanlarını seçer ve bu elemanları tek tek analiz eder. Dinamik rahatlama, malzemenin yerçekimi ile kendiliğinden şekil almasını sağlayan topolojik şekildeki kemer yapının optimizasyonunu sağlar. Evrimsel şekil optimizeri ise serbest forma en uygun alanı seçmek için en az deplasman yaptıracak strüktürel eleman yerleşmesini analiz eder. Evrimsel strüktür optimizeri ise sistemde vektörel gerilimi azaltmaya yönelik analizler yapar.
Strüktür modellerinden zincir eğrisi modelinde zincir, yerçekimine karşı oluşan eğrinin formunu alır. Bükülme, malzemenin kırılma noktasının gelişen teknoloji ve yeni malzemelerle eşik değerinin artması sonucunda, eski kırılma noktasının bükülmesiyle oluşan formdur. Minimal yüzeyler, minimum yüzey-gerilim potansiyel enerjisine sahip ve alan olarak da minimum olan formlardır. Nurbs ise üniform olmayan çizgiler eğrisidir ve bu eğriler, bir strüktür modelinde geometrinin haritalamasını yaparak serbest form yapıların strüktüre referans olabilecek olası çizgi ve yüzey ilşikilerinin hesaplanmasında kullanılırlar.
Matematiğin bir model oluşturduğu bu strüktür sistemlerinde, bilgisayar ortamında oluşan simülasyon, geçmişin sıkıcı ve anlaması zor olan hesaplamalarını geride bırakıp mimar ve mühendislere ortak olarak kullanabilecekleri bir ara yüz oluşturmuştur.

          Anahtar Kelimeler: Strüktür Tasarımı, Karmaşıklık Kuramı, Optimizasyon, Geometri, Kendi kendini Organize Etme, Topoloji

The authors discuss the overall structural design of a self-contained hydraulic six-legged machine, called MECANT I, which has been constructed for studying possible applications of legged vehicles in natural environments, like forests. First, the main mechanical solutions and control hardware of the machine are presented. The systematic approach to the motion planning of a legged vehicle and some algorithmical features are discussed. The special features of the leg control are presented. The use of a simulator in the design work is discussed, and the main principles of the control software structure, which supports fast software design and testing, are presented. Some continuing research topics and the present situation are discussed

In recent decades, shear walls and tube structures have been the most appropriate structural forms for the construction of high-rise concrete buildings. Thus, recent Reinforced Concrete (RC) tall buildings have more complicated structural behaviour than before. Therefore, studying the structural systems and associated behaviour of these types of structures is very important. The main objective of this paper is to study the linear and nonlinear behaviour of one of the tallest RC buildings, a 56-storey structure, located in a high seismic zone in Iran. In this tower, shear wall systems with irregular openings are utilized under both gravity and lateral loads and may result in some especial issues in the behaviour of structural elements such as shear walls and coupling beams. The analytical methodologies and the results obtained in the evaluation of life-safety and collapse prevention of the building are also discussed. The weak zones of the structure based on the results are introduced, and a detailed discussion of some important structural aspects of the high-rise shear wall system with consideration of the concrete time dependency and constructional sequence effects is also included. Copyright © 2010 John Wiley & Sons, Ltd.

The characterization of the prominent features of near-fault pulse-like ground motions is under scrutiny. Relationships between pulse characteristics and the performance of structures are here established. Two wavelet energy-based signal processing procedures are introduced. The aim is the construction of simplified signals containing the prominent features of the data distribution recorded from pulse-like earthquakes; signals that can be efficiently used in the design of civil engineering structures, increasing the safety and reliability of the structural design itself. The first procedure is based on the analysis of the absolute input energy. The second one considers the relative input energy. Comparisons with other wavelet-based earthquake analyses are developed.

email: [email protected], http://www.cee.ltu.se SUMMARY: The Swedish IT-stomme (IT-structure) project is a two year research project, which is aimed at applying product models in practice and developing modelling tools for cast in place concrete structures. Implementations and applications discussed in this paper are mainly driven by the interests from a ready mixed concrete supplier who identified product modelling as a threat and as an opportunity for its business process. A number of product model dimensions is discussed that result from combining different software applications. An example of a potential n th dimension of product model development and use is given, in addition to a product model's 2 nd , 3 rd , 4 th and 5 th dimension. The n th dimension is illustrated by integrating a product model with results from a program used to calculate the optimal drying process for concrete slabs. This paper concludes by discussing main challenges for the uptake of product mod...

Il periodo di vibrazione fondamentale svolge un ruolo fondamentale nella valutazione della domanda sismica. Il suo valore dipende dalle distribuzioni di massa e rigidezza nella struttura in esame ed è in genere valutato mediante analisi numeriche o, per alcune tipologie strutturali ricorrenti, mediante formulazioni empiriche semplificate. Nel presente articolo vengono presentati i risultati di una campagna sperimentale di identificazione dinamica di torri in muratura ricadenti nel territorio molisano. Queste ...

Splitting tensile strength (STS) is one of the concrete mechanical properties that are used in structural design. It can be related to numerous parameters, which include compressive strength, water/binder (W/B) ratio and concrete age. Until now, most researchers estimated the STS directly from compressive strength data. This paper suggests formulae that relate STS with that of compressive strength, W/B ratio and concrete age. The predicted STS can be obtained accurately using these formulae. It is proposed that the equation with the concrete age (t) parameter be used in predicting the STS of high-performance concrete (HPC). © 2002 Elsevier Science Ltd. All rights reserved.

http://www.sciencedirect.com/science/article/pii/S0008884602007688

One of the evocative structural design solutions for sustainable tall buildings is embraced by the diagrid (diagonal grid) structural scheme. Diagrid, with a perimeter structural configuration characterized by a narrow grid of diagonal members involved both in gravity and in lateral load resistance, has emerged as a new design trend for tall-shaped complex structures, and is becoming increasingly popular due to aesthetics and structural performance. Since it requires less structural steel than a conventional steel frame, it provides for a more sustainable structure. This study focuses on the structural performance of a steel tall building, using FEM nonlinear analyses. Numerical comparisons between a traditional outrigger system and different diagrid configurations (with three different diagrid inclinations) are presented for a building of 40 stories, with a total height of 160m, and a footprint of 36m x 36m. The sustainability of the building (in terms of structural steel weight sa...

In this paper, a variety of wafer level packaging (WLP) structures, including both fan-in and fan-out WLPs, are investigated for solder joint thermo-mechanical reliability performance, from a structural design point of view. The effects of redistribution layer (RDL), bump structural design/material selection, polymer-cored ball application, and PCB design/material selection are studied. The investigation focuses on four different WLP technologies: standard WLP (ball on I/O WLP), ball on polymer WLP without under bump metallurgy (UBM) layer, ball on polymer WLP with UBM layer, and encapsulated copper post WLP. Ball on I/O WLP, in which solder balls are directly attached to the metal pads on silicon wafer, is used as a benchmark for the analysis. 3-D finite element modeling is performed to investigate the effects of WLP structures, UBM layer, polymer film material properties (in ball on polymer WLP), and encapsulated epoxy material properties (in copper post WLP). Both ball on polymer and copper post WLPs have shown great reliability improvement in thermal cycling. For ball on polymer WLP structures, polymer film between silicon and solder balls creates a ‘cushion’ effect to reduce the stresses in solder joints. Such cushion effect can be achieved either by an extremely compliant film or a ‘hard’ film with a large coefficient of thermal expansion. Encapsulated copper post WLP shows the best thermo-mechanical performance among the four WLP structures. Furthermore, for a fan-out WLP, it has been found that the critical solder balls are the outermost solder balls under die-area, where the maximum thermal mismatch takes place. In a fan-out WLP package, chip size, other than package size, determines the limit of solder joint reliability. This paper also discusses the polymer-cored solder ball applications to enhance thermo-mechanical reliability of solder joints. Finally, both experimental and finite element analysis have demonstrated that making corner balls non-electrically connected can greatly improve the WLP thermo-mechanical reliability.

This paper presents a combined shape and reinforcement layout optimization method of shell structures. The approach described in this work is applied to optimize simultaneously the geometry of the shell mid-plane as well as the layout of surface stiffeners on the shell. This formulation involves a variable ground structure, since the shape of the shell surface is modified in the course of the process. Here we shall consider a global structural design criterion, namely the compliance of the structure, following basically the classical problem of distributing a limited amount of material in the most favourable way. The solution to the problem is based on a finite element discretization of the design domain. The material within each of the elements is modelled by a second-rank layered Mindlin plate microstructure. By a simple modification, this type of microstructure can be used to find the optimum distribution of stiffeners on shell structures. The effective stiffness properties are computed analytically through a “smear-out” procedure. The proposed method has been implemented into a general optimization software called Odessy and satisfactorily applied to the solution of some numerical examples, which are illustrated at the end of the paper.