Structural Design

A conceptually new structural design approach has recently been proposed by the authors to predict the resistance of stainless steel members subjected to various types of loading with cross-sections formed from thin flat plates including angles, channels, lipped channels, I-sections and rectangular hollow sections (RHS). The proposed method does not follow the traditional cross-section classification approach, which primarily relies on the assumption of a bilinear, elastic-perfectly-plastic material model. Instead, deformation capacity of a cross-section is determined directly from the local buckling characteristics of the constituent plate elements. This is then used to obtain the corresponding local buckling stress utilising an appropriate material model. This basic concept is extended herein to predict compression resistance of stainless steel columns with circular hollow sections (CHS). Available test and finite element (FE) results have been used to develop the basic design equation to predict the compression resistance of cross-sections and to propose column curves to determine flexural buckling resistances. The predicted resistances have been compared to those obtained using the current Eurocode; the predictions are significantly more accurate and more consistent than those given by the existing Eurocode.

The paper describes the test results of an ongoing major European research project which is concerned with the further development and refinement of structural design guidance for stainless steel. The paper concentrates on the work carried out to date on the design of beams, columns and beam-columns and compares the test results with resistances predicted by the design pre-standard for structural stainless steel, ENV 1993-1-4. In general, the design guidance is conservative. The tests on CHS beams indicate that the limiting diameter-to-thickness ratios for section classification can be considerably increased. For welded I-section beams, the ENV 1993-1-4 lateral torsional buckling curve appears very conservative and the less conservative curve adopted in ENV 1993-1-1 for carbon steel appears to give a better fit to the data.

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

| Carbon fibre polymer composites have evolved over the years to become major structural materials for primary structures of the aircraft today. The paper reviews the work carried out over last four decades on carbon fiber polymer composites to create an understanding of their behaviour in order to set up a philosophy of design and arriving at design allowable values for strength so as to ensure safety and performance of aircraft with minimum weight penalty. The rationale behind the choice of allowable values and the process to arrive at them is explained. While several issues are discussed, three major aspects are emphasised: the environmental (hygrothermal) effect, the effect of holes and fasteners and impact damage. The directions of the current improvements and course of future developments are indicated in relation to their influence on the design allowables.

The paper begins with a discussion on new ways of using computers based on knowledge engineering. Expert systems are defined as computer programs which attempt to model the performance of human experts within their respective domains. Simple architectural examples are provided for each class of knowledge that expert systems can deal with. An analysis of the requisite characteristics of expert systems in architecture is presented. The generic areas in architecture in which expert systems can play a role are described and examples are provided of prototypical expert systems based on a general expert system builder. These include evaluation using the knowledge in a specific planning code and synthesis of decisions using a designer's knowledge. The expert system builder is written in Prolog implemented under Unix. Implications of the availability of expert systems in architecture are explored.

While a significant effort is currently being undertaken by the CHI community in order to apply and extend current usability evaluation techniques to new kinds of interaction techniques very little has been done to improve the reliability of software offering these kinds of interaction techniques. As these new interaction techniques are currently more and more used in the field of command and control safety critical systems the potential of incident or accidents increases. Similarly, the non reliability of interactive software can jeopardize usability evaluation by showing unexpected or undesired behaviors. Lastly, iterative design processes promote multiple designs through evolvable prototypes in order to accommodate requirements changes and results from usability evaluations thus reducing reliability of the final system by lack of global and structured design. The aim of this SIG is to provide a forum for both researchers and practitioners interested in safety critical interactive systems. Our goal is to define a roadmap of activities to cross fertilize usability, reliability and safety for these kinds of systems to minimize duplicate efforts and reuse knowledge in all the communities involved.

Aspects of the morphology of 3 related Neogene species of Bolivinita are described and some features are related to the structural design of the shells. Possible hydromechanical consequences of the architectural differences between B. quadrilatera (rectangular spiral profile) and B. compressa (flattened, alate, spiral profile) are inferred but, qualitatively, no outstanding advantages of the descendant alate form (B. compressas are apparent. Both taxa occupied deep water biotopes. Biometric data on spiral shape of the species (topotypic or near topotypic material) does not support previous views that B. pobana was the immediate ancestor of B. com pressa. Toothplate construction in the group involves partial closure of the antecedent aperture. The location and shape of the tooth plate indicate that it would impede rather than Iaci litate the passage of cytoplasm.

One of the most important practical considerations in the optimization of steel structures is that structural members are generally to be selected from available steel pro®les. Furthermore, the solutions produced according to the national speci®cations are undoubtedly valuable from the point of view of applicability in real-life practice. This paper reports the development of a computer-based systematic approach for discrete optimal design of planar and space structures composed of one-dimensional elements. The main characteristic of the solution methodology is the use of a genetic algorithm (GA) as the optimizer. Applications and experience on steel frame and truss structures are discussed. The results of comparative studies of the GA against other various discrete and continuous optimization algorithms for a class of representative structural design problems are reported to show the eciency of the former. It is observed that a GA often ®nds the region of the search space containing the global optimum, but not the true optimum itself. Also, in this study an approach based on a proposed multilevel optimization is tested and proved to overcome this shortcoming. #

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

Optimal shape design of structural elements based on boundary variations results in final designs that are topologically equivalent to the initial choice of design, and general, stable computational schemes for this approach often require some kind of remeshing of the finite element approximation of the analysis problem. This paper presents a methodology for optimal shape design where both these drawbacks can be avoided. The method is related to modern production techniques and consists of computing the optimal distribution in space of an anisotropic material that is constructed by introducing an infimum of periodically distributed small holes in a given homogeneous, i~otropic material, with the requirement that the resulting structure can carry the given loads as well as satisfy other design requirements. The computation of effective material properties for the anisotropic material is carried out using the method of homogenization. Computational results are presented and compared with results obtained by boundary variations.

UK government Policy Planning Guidance promotes optimum use of the existing building stock through mixed use in urban centres and encourages conversion of redundant office and retail space into leisure, service or residential uses. Whilst social pressures are evident in the push to more effectively utilise existing building stock, new building stock also has to meet the commercial requirements of the client, which often translates into maximum occupancy of the building. This is encouraging greater innovation in the design of new buildings to allow change of use throughout the structure's lifetime. This paper describes the concepts surrounding an adaptable design for new buildings, along with a review of factors influencing the mode of use. The major physical parameters of storey height, building proximity, plan depth, structural design, services, fire safety, cladding and noise abatement are evaluated in the context of adaptable building use.

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.

Computations performed using end-user developed spreadsheets have resulted in serious errors and represent a major control risk to organizations. Literature suggests that factors contributing to spreadsheet errors include developer inexperience, poor design approaches, application types, problem complexity, time pressure, and presence or absence of review procedures. We explore the impact of using a structured design approach for spreadsheet development. We used two ®eld experiments and found that subjects using the design approach showed a signi®cant reduction in the number of`linking errors,' i.e., mistakes in creating links between values that must connect one area of the spreadsheet to another or from one worksheet to another in a common workbook. Our results provide evidence that design approaches that explicitly identify potential error factors may improve end-user application reliability. We also observed that factors such as gender, application expertise, and workgroup con®guration also in¯uenced spreadsheet error rates. # (D. Janvrin), [email protected] (J. Morrison) 0378-7206/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 -7 2 0 6 ( 9 9 ) 0 0 0 2 9 -4

The structure of the skin in the epauletted fruit bat ( Epomophorus wahlbergi ) wing and body trunk was studied with a view to understanding possible adaptations for gas metabolism and thermoregulation. In addition, gas exchange measurements were performed using a respirometer designed for the purpose. The body skin had an epidermis, a dermis with hair follicles and sweat glands and a fat-laden hypodermis. In contrast, the wing web skin was made up of a thin bilayered epidermis separated by a connective tissue core with collagen and elastic fibres and was devoid of hair follicles and sweat glands. The wings spanned 18-24 cm each, with about 753 cm 2 of surface exposed to air. The body skin epidermis was thick (61 ± 3 µ m, SEM), the stratum corneum alone taking a third of it (21 ± 3 µ m). In contrast, the wing web skin epidermis was thinner at 9.8 ± 0.7 µ m, with a stratum corneum measuring 4.1 ± 0.3 µ m (41%). The wing capillaries in the wing web skin ran in the middle of the connective tissue core, with a resultant surface-capillary diffusion distance of 26.8 ± 3.2 µ m. The rate of oxygen consumption ( w O 2 ) of the wings alone and of the whole animal measured under light anaesthesia at ambient temperatures of 24 ºC and 33 ºC, averaged 6% and 10% of the total, respectively. Rate of carbon dioxide production had similar values. The membrane diffusing capacity for the wing web was estimated to be 0.019 ml O 2 min -1 mmHg -1 . We conclude that in Epomophorus wahlbergi , the wing web has structural modifications that permit a substantial contribution to the total gas exchange.

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.

Historic Building Information Modelling (HBIM) is a novel prototype library of parametric objects, based on historic architectural data and a system of cross platform programmes for mapping parametric objects onto point cloud and image survey data. The HBIM process begins with remote collection of survey data using a terrestrial laser scanner combined with digital photo modelling. The next stage involves the design and construction of a parametric library of objects, which are based on the manuscripts ranging from Vitruvius to 18th century architectural pattern books. In building parametric objects, the problem of file format and exchange of data has been overcome within the BIM ArchiCAD software platform by using geometric descriptive language (GDL). The plotting of parametric objects onto the laser scan surveys as building components to create or form the entire building is the final stage in the reverse engineering process. The final HBIM product is the creation of full 3D models including detail behind the object's surface concerning its methods of construction and material make-up. The resultant HBIM can automatically create cut sections, details and schedules in addition to the orthographic projections and 3D models (wire frame or textured) for both the analysis and conservation of historic objects, structures and environments. Ó

The present article presents a synthesis of the guiding principles in four areas of crisis management, planning, coordination, leadership and civil behaviour, and outlines interventions in organizational development that may contribute to the achievement of these principles. This OD incursion stems from the observation that despite advances in the knowledge of crisis management, organizations apply them to a greater or less degree, so that dysfunctional behaviour continues to operate against an efficient resolution of crises. This observation is confirmed by a qualitative meta-analysis based on five major disasters that strike many countries around the world in the last 10 years. Various interventions proposed by OD in terms of human processes, structural design and human resource management, as well as strategy, could possibly be coupled with crisis management guiding principles to increase individuals' and organizations' resilient capacities in times of crises. The conclusion lays out the necessary conditions for cross-fertilization of the two fields.

This paper intends to report the problems and challenges that lie ahead in transistor design methodology in nano-CMOS structure. Thus, it is desired to see the options in improving the device design on top of continuing the scaling process of transistor in the next few years to come. The main concern is to see how the transistors behave as the size of device shrinks down to below 100nm range. Besides, the demand of future generations is expected as a result of more compact of digital circuit. It is concluded that although several problems surfaces as the transistor enters the nano-CMOS era, there are excellent options to solve those problems and thus could help to reduce the transistor size and yet uncompromised the device performance.

A design method for reverse osmosis desalination plants has been developed. It incorporates rigorous mathematical models for the prediction of the performance of various process units (reverse osmosis modules, pumps, energy recovery turbines) employed in the flowsheet and takes into account the network structure using an appropriate superstructure, which represents various reverse osmosis networks. Cost equations relating the capital and operating cost to the design variables, as well as the structural variables of the designed network have been introduced in the objective function. The total cost of the plant is minimized in order to determine the optimal operating and structural variables. The model is accurate enough to describe the process and yet simple enough to be used for design purposes. During the simulation and optimization studies, several structures for multistage reverse osmosis systems have been found. Results concerning the economics of the process are presented. Optimal results have also been used for the derivation of design curves concerning the effect of quality and quantity of produced water to the total annualized cost of the plant for various types of membrane modules.

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

Mining and Data Warehousing are two most significant techniques for pattern detection and concentrated data management in present technology. ELearning is one of the most important applications of data mining. The foremost idea is to provide a proposal for a practical model and architecture. The standards and system structural design are analyzed here. This paper provides importance to the combination of Web Services on the e-Learning application domain, because Web Service is the most complex choice for distance education during these days. The process of e-Learning can be promising more efficiently by utilizing of Web usage mining. Mor07/e sophisticated tools are developed for internet customer's behaviour to boost sales and profit, but no such tools are developed to recognize learner's performance in e-Learning. In this paper, some data mining techniques are examined that could be used to improve web-based learning environments.

In November 1995, at the E&P Forum Workshop on 'Uncertainties in the Design Process', the reliable determination of a suitable air-gap for setting the minimum deck elevation on offshore structures was identified as one of the most important areas of uncertainty in the design process. Most of the uncertainty in air-gap

We report low noise multiplication region structures designed for avalanche photodiodes grown on InP substrates. By either implementing a single heterostructure or using a pseudograded structure in the multiplication region, better control of spatial distribution of impact-ionization for both injected and feedback carriers can be achieved; localization of the carrier impact ionization process has resulted in very low excess noise.

Power dissipation from a low power integrated circuit is reported. The IC implements an adaptive version of the cross-correlation derivative algorithm for the estimation of interaural time difference. The architecture and logic structure as well as measured results reporting the performance of the IC-fabricated in a standard CMOS 0.5µm process-are shown.

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.

The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts results not only in a more systematic layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-storey building. To investigate the problem of openings in beams, the author initiated a research program in the early 1980s. Since then extensive research has been carried out giving a comprehensive coverage on both circular and large rectangular openings under various combinations of bending, shear and torsion. In this paper, major findings relevant to the analysis and design of such beams under the most commonly encountered loading case of bending and shear are extracted and summarized. An attempt has been made to answer the frequently asked questions related to creating an opening in an already constructed beam and how to deal with multiple openings. It has been shown that the design method for beams with large openings can be further simplified without sacrificing rationality and having unreasonable additional cost.

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.

The need for a consistent seismic design philosophy to establish design shear forces for reinforced concrete columns of bridges and buildings under seismic attack is discussed. It is shown that because of a combination of the effects of conservatism in flexural strength design equations and approximations in representation of seismic loads for analysis purposes, real shear forces generated during earthquakes may exceed three times the shear corresponding to code levels of seismic latera/loads. Existing U.S. and New Zealand design expressions for shear strength of circular columns are discussed and compared with results from a comprehensive test program involving 25 circular columns tested under axial load and cyclic lateral inelastic displacements. It is shown that existing design equations are inconsistent and very conservative for initial shear strength. The experimental results indicate, however, that the shear strength reduced with increasing flexural ductility for displacement ductility factors in excess of 2. A model for the influence of flexural ductility on shear strength is advanced, with design equations for initial shear strength applicable for low flexural ductilities, and for final shear strength applicable for fully ductile flexural designs.

Considerations and techniques are proposed that reduce the complexity ofprograms by dividing them into functional modules. This can make it possible to create complex systemsfrom simple, independent, reusable modules. Debugging and modifying programs, reconfiguring I/O devices, and managing large programming projects can all be greatly simplified. And, as the module library grows, increasingly sophisticated programs can be implemented using less and less new code.

Fax 0044 131 6508019 Abbreviated title: Structural design of Gothic vaults in England Structural design of Gothic vaults in England 2 ABSTRACT The introduction of rib systems in High Gothic vaults in England initiated a period of greater ambition in the design of churches, while subsequent experimentation increased the confidence of the masons in working with more complex forms. This development is discussed through the study of the structural behaviour and efficiency of vaults at the cathedrals of Durham, Canterbury, Wells and Lincoln that represent significant technical innovations. The collapse mode and safety margin of the original designs is examined, focusing on the dominant action that results from failure of the buttressing system. The study highlights how the integrity of the fabric provided by the rib had to be enhanced by refinements of the form and lateral support. Although the discussion shows a consistent development, each of the innovations brought individual solutions that this study attempts to treat as options available to the masons. KEYWORDS Gothic architecture, vaults, structural safety, England, structural design Structural design of Gothic vaults in England 3