Academic literature on the topic 'Concrete beams – Design and construction – Computer programs'

The engineering community has been striving to design more sustainable buildings in an attempt to reduce both environmental impact and energy use during all phases of design, construction and operation. Design professionals currently have very limited guidance or tools to incorporate life-cycle and sustainability concepts into their designs. After reviewing the capabilities and limitations of four current life cycle analysis (LCA) computer programs, this research has selected the Athena Impact Estimator v4.0 to perform parametric studies of structural members made up of different construction materials. The energy consumption values are calculated and compared for columns, beams, concrete suspended slabs, precast double-tee sections and various other floor types. While Athena did offer some insights based on its LCA results, this research has concluded that existing LCA and sustainability analysis programs have too few options to meet the current needs of design professionals. A more accurate, sophisticated whole-building LCA tool needs to be developed to assess sustainable properties of design alternatives and to produce the most sustainable structural systems.

Most computer programs developed for reinforced concrete beam design either analyze a given cross section for load capacity or offer a limited solution from which the engineer must continue toward the final design. These programs are very useful in performing many tedious calculations. However, they generally do not offer assistance in areas of design that require intuitive reasoning, experiential knowledge, rules of thumb, and sound engineering judgement. This type of heuristic knowledge has been incorporated into a prototype knowledge-based expert system for reinforced concrete beam design and detailing called BeamEx. BeamEx interacts with the user to advise and establish suitable parameters required for the comprehensive design of rectangular simply supported and continuous beams. It incorporates heuristic rules drawn from the governing Canadian codes and textbooks to design alternative suitable beams which are presented in graphical form. It is shown that a knowledge-based system approach can be used effectively in engineering design by encapsulating domain expertise in a program to complement and check the experience of the users in design. Key words: knowledge-based expert system, reinforced concrete, beams, design, detailing.

In the present trend of constructing taller and longer structures, the application of lightweight aggregate concrete is becoming an increasingly important advanced solution in the modern construction industry. In engineering practice, the analysis of lightweight concrete elements is performed using the same algorithms that are applied for normal concrete elements. As an alternative to traditional engineering methods, nonlinear numerical algorithms based on constitutive material models may be used. The paper presents a comparative analysis of curvature calculations for flexural lightweight concrete elements, incorporating analytical code methods EN 1992-1 and ACI 318-19, as well as a numerical analysis using the constitutive model of cracked tensile lightweight concrete recently proposed by the authors. To evaluate the adequacy of the theoretical predictions, experimental data of 51 lightweight concrete beams of five different programs reported in the literature were collected. A comparison of theoretical and experimental results showed that the most accurate predictions are obtained using numerical analysis and the constitutive model proposed by the authors. In the future, the latter algorithm can be used as a reliable tool for improving the design standard methods or numerical modeling of lightweight concrete elements subjected to short-term loading.

Analysis of the time-dependent changes in displacements, internal forces, and reactions at the supports in continuous reinforced concrete structures cast, prestressed, and loaded at different stages is frequently needed in design to satisfy the serviceability requirements. The time-dependent parameters considered in the analysis are creep and shrinkage of concrete, relaxation of prestressed steel, sequence of construction, and changes in structural system and support conditions. A procedure of analysis is presented using conventional linear analysis computer programs. The analysis procedure is explained through examples to demonstrate its simplicity and applicability.Key words: analysis, computer program, creep, displacement, frames, precast concrete, prestressed concrete, relaxation, shrinkage, time-dependent.

The design specifications of composite trusses are only partially included in the European standards. However this construction system can be considered as one of the most economical for building and bridge structures. To create an interaction between steel and concrete, it is necessary to prevent the relative slip at the steel and concrete interface using the shear connectors. But the local effects of a concentrated longitudinal shear force between steel truss chord and concrete slab, as special task, should be appropriately examined. The finite element analyses can be used to investigate numerically this structural system behaviour, exploiting several computer procedures. The experimental research has tested these procedures. The outputs of this study are presented in the paper.

Meta-programs are generic, incomplete, adaptable programs that are instantiated at construction time to meet specific requirements. Templates and generative techniques are examples of meta-programming techniques. Understanding of meta-programs is more difficult than understanding of concrete, executable programs. Static and dynamic analysis methods have been applied to ease understanding of programs — can similar methods be used for meta-programs? In our projects, we build meta-programs with a meta-programming technique called XVCL. Meta-programs in XVCL are organized into a hierarchy of meta-components from which the XVCL processor generates concrete, executable programs that meet specific requirements. We developed an automated system that analyzes XVCL meta-programs, and presents developers with information that helps them work with meta-programs more effectively. Our system conducts both static and dynamic analysis of a meta-program. An integral part of our solution is a query language, FQL in which we formulate questions about meta-program properties. An FQL query processor automatically answers a class of queries. The analysis method described in the paper is specific to XVCL. However, the principle of our approach can be applied to other meta-programming systems. We believe readers interested in meta-programming in general will find some of the lessons from our experiment interesting and useful.

Abstract The use of computers provides the opportunity to analyse and design complex structures, taking into account the geometric and physical nonlinearity of construction materials. In the article the study of stress-strain state of mixed steel-concrete beams, were presented. The results of this study showed that the method of calculation according to designe codes gave satisfactorily results of calculated strength compared with experiments. However, these methodes do not provide complete information of structural performance at all levels of load. For a more complete study of the stress-strain state and the physical nature of the processes occurring in steel-concrete structures reinforced with a mixed reinforcement, the calculation method using “Lira” software complex is proposed. The method of calculation is based on the finite element method. The calculation is made taking into account physical nonlinearity and real diagrams of σ-ε of materials using the nonlinear deformation law №14 of “Lira” software complex. The proposed method of calculation allows to determine the values of bearing capacity, the development of deformations and the beginning of crack formation, as well as stresses at all load levels.

The design of reinforced concrete beams involves the selection of design parameters such as beam dimensions and reinforcement details which result in a safe and economical section. This process of design consists of three stages: preliminary design, structural analysis, and detailed design which includes the selection of dimensions, reinforcement, and stirrups. The design process is an iterative one where considerable judgement and experience are required. This is an ideal situation for the application of expert system technology. A knowledge based expert system called BEAMDES was developed for the flexure design of reinforced concrete beams in accordance with ACI 318-83 specifications. The expert system was developed using the micro-computer based expert system shell, Insight 2+. BEAMDES can be used to design both rectangular and tee sections. The beams can be simply supported, cantilevered, or continuous. The results obtained from BEAMDES were tested against several example problems for both supported and continuous beams. It was found that the designs recommended by the system were similar to those of the examples.
Master of Science

CAPES
A falta de manutenção, a mudança de carregamentos, as deficiências de projeto, de execução e até mesmo dos materiais constituintes de uma peça estrutural podem levar à necessidade de aplicação de um reforço estrutural. Dentre estes métodos se destaca o reforço estrutural com Compósitos Reforçados com Fibra de Carbono (CRFC). Este trabalho tem como objetivo analisar o comportamento estrutural por meio de métodos experimentais e modelagem numérica de vigas biapoiadas de concreto armado reforçadas à flexão com CRFC, além de analisar a influência da adição de incrementos de ancoragem no comportamento da peça. O modelo computacional foi desenvolvido no software comercial ANSYS, por meio da utilização do Método dos Elementos Finitos. Foi avaliado o ganho de resistência com a implantação de uma e duas camadas de CRFC em comparação à viga sem reforço. A interface concreto – reforço foi considerada na simulação computacional, uma vez que os esforços atuantes nesta região geralmente são a causa da ruptura neste tipo de peça. Para isso, foi utilizado o Modelo da Zona de Coesão como método de representação da interface. Em relação ao programa experimental, além da variação do número de camadas de reforço, também foi avaliada a influência da adição de incrementos de ancoragem lateral no comportamento das vigas estudadas. Como resultados, foi alcançada uma boa acurácia entre os modelos computacionais e a análise experimental em relação ao valor da carga última de cada situação analisada, bem como em relação ao valor de deslocamento encontrado para as vigas reforçadas. Entretanto, percebeu-se que os valores das deformações obtidos no modelo computacional foram superiores à média dos valores encontrados na análise experimental. Além disso, observou-se também que as vigas tiveram sua rigidez aumentada com o acréscimo de camadas de reforço. Ademais, foi verificado que a adição de incrementos de ancoragem levou a um acréscimo na resistência das peças, mais efetivo que o aumento do número de camadas, para o caso deste trabalho.
The lack of maintenance, the change in loadings, project and execution failures, and even failures of constituent materials of a structural part lead to the necessity of applying a structural reinforcement. Among these methods highlights the structural reinforcement with Carbon Fiber Reinforced Polymer (CFRP). This research has the objective to examine whether there is a good relationship between laboratory tests and a simulation model of reinforced concrete beams strengthened in bending with CFRP, in addition to analyze the influence of anchorage increments application in the structural behavior. The computacional model was developed in the comercial software ANSYS, by the utilization of the Finite Element Modeling for the structural analysis. The resistance gain with the implementation of one and two layers of CFRP was evaluated compared with the reference beam. The concrete – reinforce interface was considered in the computacional simulation, since the active efforts in this area are the reason of this type of structure failure. Thus, the Cohesive Zone Model was used for the interface representation. In relation to the experimental tests, beyond the number of layers variation, it was also evaluated the influence of anchorage increments application in the structural behavior. As results, it was obtained a good accuracy of the computacional models and the experimental tests in relation to the rupture load, in addition to the displacements values for the reinforced beams. However, the strain values achieved by the computacional model were higher than the experimental analysis rate values. Besides, it was also noticed that the beams had an increase of the stiffness with the addition of the reinforced layers. Furthermore, it was verified that the anchorage increments application caused an increase of the resistance, even more efficient than the addition of layers, for this case of study.