Simple Design Tool Research Articles

The building performance sketch

A new approach to the creation of design tools is proposed that addresses the real information needs of designers in the early stages of design of non-residential buildings. Traditional simplified design tools are typically too limited to be of much use, even in conceptual design. The proposal is to provide access to the power of detailed simulation tools at a stage in design when little is known about the final building, but at a stage also when the freedom to explore options is greatest and the ability to improve the design is greatest. The concept of the building performance sketch forms the basis of the proposed design tool. It was derived from consultation with design analysis teams as part of the development of the COMFEN tool for fenestration design. Tools like COMFEN are explored to understand how they were shaped by consultation and how requests from these teams for real-world relevance might shape such tools in the future. The simulation process can effectively utilize some of the as-built, as-occupied and as-managed lessons on behaviours and technical outcomes from the Post-occupancy Evaluation (PoE) of buildings. Il est proposé pour la création des outils de conception une nouvelle approche répondant aux véritables besoins d'information des concepteurs dans les premières phases de conception des bâtiments non résidentiels. Les outils de conception simplifiée traditionnels sont habituellement trop limités pour être très utiles, même en design conceptuel. Ce qui est proposé est de pouvoir accéder à la puissance d'outils de simulation détaillée à un stade de la conception où l'on sait encore peu de choses concernant le bâtiment final, mais également à un stade auquel la liberté d'exploration des options possibles comme la capacité d'amélioration de la conception sont les plus grandes. Le concept du schéma de performance du bâtiment constitue la base de l'outil de conception proposé. Il découle de la consultation des équipes chargées de l'analyse de la conception dans le cadre du développement de l'outil COMFEN de conception du fenêtrage. Des outils tels que COMFEN sont examinés afin de comprendre comment ils ont été modelés par la consultation et comment les demandes de ces équipes en termes de pertinence réelle pourraient façonner ces outils à l'avenir. Le processus de simulation peut tirer efficacement parti de certaines des leçons, conformes à l'exécution, à l'occupation et à la gestion, en matière de comportements et de résultats techniques, retirées de l'Evaluation Après Occupation des bâtiments. modèles d'information du bâtiment bâtiments processus de conception outils de conception début de conception efficacité énergétique retour d'information simulation des performances évaluation après occupation

Automatic design of the flexural strengthening of reinforced concrete beams using fiber reinforced polymers (FRP)

Changing the functions of a building, the presence of some design or construction errors, the incidence of seismic actions and even the updating of design codes may demand the strengthening of certain structures. In the specific case of reinforced concrete structures it is desirable the application of a technique of strengthening which is fast, economic and efficient, in order to provide advantages when an intervention is necessary. The technique of strengthening chosen must provide less disorder as possible as well as the guaranty of safety. Taking into account this scenery, fiber reinforced polymers have been working as a very attractive alternative for rehabilitating in-service structures. In that way, the present study aims at presenting the main properties of this new material as well as the design routines for flexural strengthening of reinforced concrete beams. Finally, a package-software developed into the MATLAB platform is presented, intending to generate a simple tool for the automatic design using fiber reinforced polymers.

Assessment and Design Procedure for the Seismic Retrofit of Reinforced Concrete Beam-Column Joints using FRP Composite Materials

In this study, an analytical procedure for the evaluation of the expected performance of existing reinforced concrete (RC) beam-column joints before and after being retrofitted using fiber-reinforced polymer (FRP) composite materials is presented. Focus is given on the evaluation of the shear-strength versus deformation properties of the panel zone region either in the as-built or FRP-retrofitted configuration. Based on experimental and numerical evidence as well as on physical models representing the mechanics of the joint region, principal tensile stresses versus joint shear deformation relationships are adopted and preferred to more traditional nominal shear-strength rules, to evaluate, within a step-by-step iterative procedure, the combination of the joint shear contribution provided by the FRP composite material and that provided by the concrete core alone. The use of principal stresses allows one to directly account for the effects of variation of axial load, typically neglected in the assessment and retrofit of beam-column joints. The hierarchy of strength and sequence of events (damage mechanisms) expected within a beam-column subsystem are visualized via M-N interaction performance domains, used as a basis for a performance-based retrofit philosophy. Specific limit states or design objectives are targeted, with attention given to both strength and deformation limits. The proposed analytical procedure is validated on the results of a set of experimental tests available in the literature. With the intention to provide a simple design tool that can be easily implemented by practicing engineers, a worked example for the evaluation of the expected performance of an FRP retrofitted beam-column joint is provided and used as a basis for a parametric study to illustrate the effects of different strengthening schemes on the behavior of strengthened exterior joint panels under various axial load levels.

An Approximation for Blocking Probabilities and Delays of Optical Buffer With General Packet-Length Distributions

An all-optical network still remains a long way from realistic deployment. However, all-optical packet switches, in which optical packets are buffered and routed in optical form, are still expected to solve the problems of electronic bottlenecks and large power consumption in electronic routers. An approximation is presented for blocking probabilities and delays of optical buffers, where optical packet arrival process is Poisson and packet-length distribution is general. The approximation aims at providing a simple calculation tool for optical buffer design without requiring computer simulations or extensive iterative computations. An approximation for the cumulative distribution function of the waiting time for general packet-length distributions was obtained that holds when the waiting time is sufficiently large and the traffic load is heavy. The difference in the blocking probabilities between the approximation and the simulation results was found to be less than 10% when the offered load was greater than 0.7. The approximation can be applied to investigate multiclass optical buffers for priority queueing and to design wavelength-division-multiplexing optical packet switches and networks with the maximum throughput.

A FEASIBILITY STUDY ON MICROWAVE IMAGING FOR BRAIN STROKE MONITORING

The adoption of microwave imaging as a tool for non- invasive monitoring of brain stroke has recently gained increasing attention. In this respect, the paper aims at providing a twofold contribution. First, we introduce a simple design tool to devise guidelines to properly set the working frequency as well as to choose the optimum matching medium needed to facilitate the penetration of the probing wave into the head. Second, we propose an imaging strategy based on a modifled formulation of the linear sampling method, which allows a quasi real time monitoring of the disease's evolution. The accuracy of the design guidelines and performance of the imaging strategy are assessed through numerical examples dealing with 2D anthropomorphic phantoms.

Global Interventions for Seismic Upgrading of Substandard RC Buildings

A methodology is developed in this paper for the design and proportioning of interventions for seismic upgrading of substandard reinforced-concrete (RC) buildings. The retrofit approach is presented in the form of a simple design tool that aims toward both demand reduction and enhancement of force and deformation supply through controlled modification of stiffness along the height of the building. This objective is achieved by engineering the translational mode-shape of the structure, so as to optimize the distribution of interstory drift. Results from the proposed approach are summarized in a spectrum format in which demand, expressed in terms of interstory drift, is related to stiffness. Design charts, which relate the characteristics of commonly used global intervention procedures to influence drift demands, are developed to facilitate the retrofit design. The intervention procedures considered in this paper are reinforced-concrete jacketing, the addition of reinforced-concrete walls, and the addition of masonry infills. The proposed methodology is also amenable to adaptation to other strengthening methods, such as the addition of cross-bracing.

Numerical modelling: a tool for better constructed wetland design?

There is a need for a simplified computer-based design tool for subsurface flow constructed wetlands (CWs) which is based on process-based numerical models. Parameters of existing design guidelines and rules have been derived from experiments under specific conditions. Therefore designing CWs using these parameters is limited to these conditions (i.e., temperature, wastewater composition, filter material, etc.). Process-based numerical models describe the main processes in CWs in detail. If the design of CWs is based on these models it will be possible to design CWs for a variety of different boundary conditions and therefore the main limitation of existing design guidelines and rules could be overcome. The use of process-based models is currently limited mainly due to their complexity in structure and use. To make numerical modelling a useful and applicable tool for design, a simplified computer-based design tool that does not require special knowledge of numerical modelling is needed. Additionally, simple models for pre- and post-treatments are also required. Besides allowing designs for various boundary conditions, design tools based on process-based models can also predict the dynamic behaviour of the designed system thus showing e.g., the higher robustness of CWs against fluctuating inflows and peak loads compared to other treatment solutions. Such a tool could increase the quality of CW design and the acceptance and use of CW simulation in practice.

Possibilities and comparison of structural component models for the seismic assessment of modern unreinforced masonry buildings

This paper addresses the possibilities of structural component models for the seismic assessment of masonry buildings using pushover analysis. The ultimate goal is to allow efficient design of new unreinforced masonry buildings in seismic areas. Different modelling strategies are presented and the implementation of a simple design tool based on structural component models is described in detail. The different approaches are applied to a two-storey building with regular plan and elevation, allowing for a comparison between them. The results indicate that macro-modelling using structural component models and pushover analysis are adequate approaches for the seismic assessment and design of unreinforced masonry buildings, as the tools require very low computational resources, allow easy interpretation of results and provide satisfactory accuracy.

A Neural-Network Model-Based Engineering Tool for Blast Wall Protection of Structures

Blast barrier walls have been shown to reduce blast loads on structures, especially in urban environments. Analysis of existing test and simulation data for blast barrier response has revealed that a need still exists to determine the bounds of the problem and produce a fast-running accurate model for the effects of barrier walls on blast wave propagation. Since blast experiments are very time intensive and extremely cost prohibitive, it is vital that computational capabilities be developed to generate the required data set that can be utilized to produce simplified design tools. The combination of high fidelity model-based simulation with artificial neural network techniques is proposed in this paper to manage the challenging problem. The proposed approach is demonstrated to estimate the peak pressure, impulse, time of arrival, and time of duration of blast loads on buildings protected by simple barriers, using data generated from validated hydrocode simulations. Once verified and validated, the proposed neural-network model-based simulation procedure would provide a very efficient solution to predicting blast loads on the structures that are protected by blast barrier walls.

Optical design of color light-emitting diode ring light for machine vision inspection

Uniform irradiance and color adjustability are the key features in the design of lighting for machine vision inspection systems. A simple and practical design tool of angled light-emitting-diode (LED) ring arrays for uniform near-field irradiance has been developed by introducing a simple model to simplify the complexity of nonrotational symmetric irradiance distribution of angled LEDs. The color distribution and color uniformity of the ring array assembled with RGB LEDs are analyzed based on the analytical model of color mixing. According to the theoretical analysis, the simulated results, and the design exemplifications, the practical design tool offers an easy way to estimate the performance of an RGB LED ring array and can be considered as a starting point to reduce the computation time for exact designs that must use a realistic LED model.

Bridge Piers with Structural Fuses and Bi-Steel Columns. II: Analytical Investigation

This paper presents the results of an analytical investigation conducted to replicate experimentally obtained behavior, and better understand the behavior of the proposed structural fuse concept for bridges that is presented in a companion paper. First, a steel plate shear link (SPSL) proposed as a new type of structural fuse is described. Equations are derived to define its shear-moment interaction equation, to determine some of its critical design parameters, and to quantify the link ductility, lateral stiffness and strength. Strengths and stiffnesses equations are developed using free-body diagrams (FBDs) for the tested systems as a convenient simple design tool. Finite-element models (FEM) are developed by using the finite-element software package ABAQUS/explicit to validate the proposed SPSL concept, and then to replicate the full range of results obtained from the experiments. Comparisons between the analytical and experimental results are conducted to highlight the differences in behavior among all tested specimens. The simple numerical equations correctly represent the expected strengths and stiffnesses of the fuse systems. Further, the results obtained from the ABAQUS model accurately captured the global behavior of the system, and provided valuable insight into individual fuse behavior.

Deformation and consolidation around encased stone columns

A new analytical solution is presented to study soft soil improvement by means of encased stone columns to reduce both settlement and consolidation time. The proposed solution aims to be a simple and useful tool for design. Only a unit cell, i.e. an end-bearing column and its surrounding soil, is modelled in axial symmetry under a rigid and uniform load. The soft soil is treated as an elastic material and the column as an elastic–plastic material using the Mohr–Coulomb yield criterion and a non-associated flow rule, with a constant dilatancy angle. An elasto-plastic behaviour is also considered for the encasement by means of a limit tensile strength. The solution is presented in a closed form and is directly usable in a spreadsheet. Parametric studies of the settlement reduction, stress concentration and consolidation time show the efficiency of column encasement, which is mainly ruled by the encasement stiffness compared to that of the soil. Column encasement is equally useful for common area replacement ratios but columns of smaller diameters are better confined. Furthermore, the applied load should be limited to prevent the encasement from reaching its tensile strength limit. A simplified formulation of the solution is developed assuming drained condition. The results are in agreement with numerical analyses.

Simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems

This paper describes the development of a simplified calculation method for design cooling loads in underfloor air distribution (UFAD) systems. The simplified design tool is able to account for key differences between UFAD and traditional mixing overhead (OH) systems. These include: (1) difference between design day cooling load profiles, (2) impact of a thermally stratified environment for UFAD versus well-mixed for OH, and (3) impact of heat transfer (temperature gain) in underfloor air supply plenums. The new design tool allows the use of a familiar load calculation procedure for OH mixing systems as input to the UFAD design tool. Based on 87 EnergyPlus simulations, four regression models have been developed to transform the OH cooling load into the UFAD cooling load, and then to split this total load between the supply plenum, zone (room), and return plenum. The regression models mainly depend on floor level, and position (interior or perimeter) and orientation of the zone under analysis. Although considered in the analysis, supply air temperature, window-to-wall ratio, internal heat gain, plenum configuration, climate, presence of the carpet and structure type do not strongly influence the developed models. The results show that, generally, UFAD has a peak cooling load 19% higher than an overhead cooling load and 22% and 37% of the total zone UFAD cooling load goes to the supply plenum in the perimeter and interior, respectively.

An element addition strategy for thermally actuated compliant mechanism topology optimization

PurposeThe purpose of this paper is to describe an element addition strategy for topology optimization of thermally actuated compliant mechanisms under uniform temperature fields.Design/methodology/approachThe proposed procedure is based on the evolutionary structural optimization (ESO) method. In previous works, this group of authors has successfully applied the ESO method for compliant mechanism optimization under directly applied input loads. The present paper progresses on this work line developing an extension of this procedure, based on an additive version of the method, to approach the more complicated case of thermal actuators.FindingsThe adopted method has been tested in several numerical applications and benchmark examples to illustrate and validate the approach, and designs obtained with this method are compared favorably with the analytical solutions and results derived by other authors using different optimization methods, showing the viability of this technique for uniformly heated actuators optimization.Research limitations/implicationsAs a simple initial approach, this research considers only uniform heating of the system, while many thermal actuators are heated nonuniformly. Future works will be based on electrothermal actuation, and nonuniform Joule heating will be considered as well, which might lead to more elegant and efficient solutions.Practical implicationsCompliant micromechanisms that are responsible for movement play a crucial role in microelectromechanical systems (MEMS) design, which cannot be manufactured using typical assembly processes and may not make use of traditional hinges or bearings. The topology optimization method described in this paper enables the systematic design of these devices, which can result in reduced conception time and manufacturing cost.Originality/valueThe ESO method has been successfully applied to several optimum material distribution problems, but not for thermal compliant mechanisms. Even if most applications of this method have been oriented for maximum stiffness structure design, this paper shows that this computation method may be also useful in the design of thermal compliant mechanisms and provides engineers with a very simple and practical alternative design tool.

Interaction diagrams for ambient and heated concrete sections

Bending moment axial force interaction diagrams are a commonly used tool in any design office. When designing for fire conditions, the large axial forces which develop place an additional importance on the consideration of the interplay between axial forces and moments. This paper presents a new method for calculating the biaxial bending moment/axial force capacity for a general section through the use of the sectional tangent stiffness. A beam–column section subject to fire is assessed, and comparisons made with simplified design tools. It is concluded that derivation of the interaction surface from the tangent stiffness matrix is possible, and that current simplified methods for fire design cannot be assumed conservative.

Lifecycle assessment for sustainable design options of a commercial building in Shanghai

Buildings are long-lasting products which have huge impacts on the environment during their whole lives. The design of buildings should take into consideration long-term environmental and economic benefits. A life cycle assessment approach is developed and demonstrated in a case study—the strategic design of a Flagship Store in Shanghai. Industrial practitioners were invited to the feasibility study. Their opinions were included in the life cycle assessment for the first time. The economic analysis takes account of not only the capital costs of the design options but also the running costs during the building's economic life cycle. The methodology adopted is an integrated life cycle assessment process including life cycle costing, multi-criteria decision making and group decision making methods. The workshops are successful in terms of educational opportunity for the practitioners and have obtained good feedbacks. The top 10 sustainable design options after the life cycle assessment process were chosen by the practitioners as the compulsory design strategies in their global environmental development agenda, whilst the other 32 design options as optional design solution for the international retailer's future stores. The life cycle assessment tool demonstrated by a case study was proven to be a simple and efficient design tool in practice, and therefore it can be adopted in other projects to assist the decision makers.

Ferrite Toroidal Inductor Design

A non iterative method for toroidal inductor design is proposed introducing an equation for fast estimation of the core size required as function of the wanted inductance and the maximum values specified for induction and current. Also, the core volume obtained may be compared with the one required for air gap core implementation, in order to assess an eventual oversizing of the selected core. By this way, a simple and fast tool for inductor design allows to decide between manufacture alternatives, material adoption or to foresee board room in converter design. Moreover, the proposed method allows design inductors accepting a broad tolerance of the core material features.

Bifurcation topology tuning of a mixed behavior in nonlinear micromechanical resonators

We report the experimental observation of a four-bifurcation-point (or five possible amplitudes for a given frequency) behavior of electrostatically actuated micromechanical resonators, called the mixed (first hardening then softening) behavior. We also demonstrate both analytically and experimentally tuning the bifurcation topology of this behavior via an electrostatic mechanism. An analytical model allows for the qualitative as well as quantitative explanation of the experiments and serves as a simple tool for design of nonlinear micromechanical devices under high drive.

Non-linear failure criteria for a double lap bonded joint

This article introduces an analytical procedure based on the well-known Shear Lag theory of Volkersen [Die nietkraftverteilung in zugbeanspruchten mit konstanten laschenquerschritten, Luftfahrtforschung 1938;15:41–7], but allowing to take into account a multilinear mechanical behaviour of the adhesive in order to determine an average shear stress profile along the bonded joint. The aim is to provide for a civil engineering application a simple design tool of bonded anchorages. Using this method, more consistent results are obtained concerning the anchorage length and a failure criteria can be expressed in terms of a maximum yielded length along the bonded joint. The validity of this criteria is assessed via an experimental investigation which includes material characterization as well as double lap joints quasi-static loading. The studied materials are a two-component commercial epoxy adhesive and glass fibre pultruded adherends. Different parameters of the joint are varied (surface preparation, adherend and bond thickness, lap length, geometrical configuration) so that it is possible to check qualitative expectations, and define a quantitative failure prediction parameter. In the last part, the shear stress profiles obtained using the described analytical procedure are compared to finite element results and good agreement is found between both approaches.

Stochastic response spectra for an actively-controlled structure

A stochastic response spectrum method is proposed for simple evaluation of the structural response of an actively controlled aseismic structure. The response spectrum is constructed assuming a linear structure with an active mass damper (AMD) system, and an earthquake wave model given by the product of a non-stationary envelope function and a stationary Gaussian random process with Kanai-Tajimi power spectral density. The control design is executed using a linear quadratic Gaussian control strategy for an enlarged state space system, and the response amplification factor is given by the combination of the obtained statistical response values and extreme value theory. The response spectrum thus produced can be used for simple dynamical analyses. The response factors obtained by this method for a multi-degree-of-freedom structure are shown to be comparable with those determined by numerical simulations, demonstrating the validity and utility of the proposed technique as a simple design tool. This method is expected to be useful for engineers in the initial design stage for structures with active aseismic control.