CURVBRG: A program for analysis of curved I-girder bridges

A computer program for structural analysis of open girder (i.e. I-section) bridge super-structures is described. The program is based on a plane grid idealization, in which the effects of warping torsion are considered rationally, and in which structural components such as diaphragms and braced (truss type) cross frames are idealized by essentially exact procedures. The bridge may be of arbitrary shape in plan, the girders may be of variable cross section along their length, and changes in form of the structure as construction progresses may be considered. Deflections, stress resultants and stresses can be determined for static loads, support settlement effects and moving live loads. The structural idealization procedure and theory are explained, the features of a computer program developed to apply the method are described, and comparisons are made between the computed behavior and that observed in a model test.     

Analysis of distortional stress in curved I girder bridges

A simplified means of determining more accurately the stress distribution in a curved girder system considering web distortion is presented. The distortional response of a single span curved plate girder bridge is determined utilizing a finite difference procedure. The analysis finds the maximum bending, warping and distortional stresses along each girder.

A UNIVAC 1108 computer was used in the development of the simplified equations which relate the bending and warping stresses to the induced distortional stress. The program written in FORTRAN V, calculates the stresses developed in a four plate girder system having any number of diaphragms along its span.     

An interactive program assists layout planning

An interactive computer program is described for layout planning. This program is a construction routine. It is written in BASIC and has been tested on an Apple II microcomputer. The program generates multi-story layouts of up to three floors with sixty-four departments per floor.     

An interactive design algorithm for prestressed concrete girders

The primary purpose of this paper is to discuss an interactive design and analysis algorithm for prestressed concrete girders. Prestressed concrete highway bridge girder design is used for the prototype computer program to simplify the incorporation of design code requirements and loading conditions. The computer code can be extended to include other prestressed concrete girder applications. The second purpose arises from the search for the optimum prestressed concrete girder design. Linear programming is discussed as a possible method to arrive at the optimum girder cross-section and prestressing strand design. However, manufacturing standardization and techniques make selection of the optimum crosssection, prestressing force, and strand centroid eccentricity by mathematical methods rather academic. Therefore, design optimization, to be practical, must be based on standard cross-sections and prestressing strand position templates. The algorithm, guided by the engineer, selects, from tabulated standard crosssections and associated combinations of prestressing forces and eccentricities, the cross-section, prestressing force, and eccentricity to satisfy the problem constraints. The kern boundaries are calculated in the analysis portion of the algorithm. The engineer, using the kern boundaries, determines the path of the strands by specifying the strand hold-down points and associated strand centroid eccentricity. The algorithm also provides for shear reinforcement, dead load deflections at transfer and after placement of the slab, and auxiliary nonprestressed tension reinforcement at transfer.     

A simple efficient hidden line algorithm

A simple efficient hidden line algorithm for finite element models is described. The algorithm is general purpose, requires minimal computer storage, and can easily be added to existing plot programs. The routine does not require angle determination, trigonometric functions, or elaborate bookkeeping schemes. Detailed flowcharts and a listing of the computer code are presented.     

A curve analyzer for micro-computers

A computer program is described that emulates a curve analyzer and fits a sum of up to 30 Gaussian components plus a straight background to any set of equi-spaced data points. The program allows interactive, real time curve fitting by the operator and/or objective curve fitting using a non-linear least squares fitting routine, or a combination of the two. The program is more robust in a micro-computer environment than subtractive or generalized non-linear least squares methods and faster than pattern searching methods. The program has been used over the last 4 years in my laboratory by a number of personnel without any previous experience of computers. It is written in BASIC and runs on a Hawlett-Packard series 200 model 16S (9816) computer or on a Hewlett-Packard model 9845S computer. The program is structured to allow use of any underlying curve shape with 3 parameters per component.     

An efficient procedure for the statistical transient analysis of switching circuits

The computer-aided statistical analysis of circuits is an indispensable tool for determining the effects of parameter tolerances on the circuit performance. However, the repeated analysis of the circuit for a statistically adequate number of random parameters, chosen according to their prescribed statistical probability densities, requires inordinate amounts of computer time and is therefore very expensive. This is especially true for non-linear circuits.

An algorithm and the corresponding program are described in this paper, which greatly reduce the computer time needed for the statistical transient analysis of switching circuits. The program uses SCEPTRE as its main transient analysis routine. Several pre-SCEPTRE and post-SCEPTREA routines have been added to obtain the desired result.     

State-of-the-art of curved girder bridge programs

This paper will present information on the numerous computer programs that have been developed which may be used to analyze or design curved girder bridges. The material is limited to programs applicable to curved bridges loaded normal to the plane of curvature and does not consider arches or rings. Specifically, the capabilities of 27 software systems are examined.     

Computerized automatic design of concrete buildings

The salient features of the AMECO system of integrated computer programs are described. The entire structural design process, from geometry generation in 2- or 3-dimensional, load calculations, etc., to productionof construction documents is computerized in to one operation. Using English language commands, the engineer inputs basic parameters, such as name of the building code, number of stories, floor required to seismic factor, typical member lengths and their connectivities. As few as 16 commands are live loads, design a building of 2000 members. Optional commands are available to input predetermined data or to modify the automatic design procedures.The results of two analyses of a 30 storey frame are presented, one using AMECO with its automatic simulation of the construction sequence, and the second one, using a stiffness matrix program. The latter analysis shows substantial discrepancies in column axial strains and girder moments, demonstrating the potential dangers in use of stiffness matrix programs for structures with high dead loads, such as tall buildings. AMECO utilizes a relaxation method for frame analysis, which produces exact, in-core solutions of a 2000 member building in less than 30 sec on a CDC 6600 computer using 33,000 words of memory.     

A C version of Fourier-derived affinity spectrum analysis (FASA) to resolve binding heterogeneity

The computer program described in this paper facilitates resolution of binding affinity heterogeneity by transforming binding curve data (bound versus free) into affinity spectra (density versus affinity). The original program, written in FORTRAN, is extended and presented here in the language C. New applications include an ability to transform competition curves into affinity spectra and to evaluate the effects of sampling and experimental error on spectrum analysis. We propose that this program be incorporated in the routine evaluation of binding systems.     

计算机硬件维护与故障分析

本文对计算机实验室电脑硬件的维护和常见故障检测方法作了较详细的介绍。     

Personal-computer based self-tuning controller

Self-tuning control is an area of control theory which has developed rapidly in the last decade. The emergence of self-tuning control has been facilitated by the great increase in power and decrease in cost of processing hardware, which now allows advanced process control techniques to be implemented with relative ease and at low cost.This paper describes a portable self-tuning controller package which has been written in fortran and implemented on an IBM portable personal computer. The package can be used in both a simulation mode and in a real-time mode for control of physical processes.A brief introduction to self-tuning control, a control algorithm based upon Linear-Quadratic-Gaussian (LQG) optimal control theory, and an estimation routine based upon least-squares techniques are presented. The LQG algorithm and the estimation routine are computationally intensive procedures and the special precautions which are necessary to ensure numerical robustness are described.The key features of the package, and the software and hardware organization used to implement it are presented.     

Calculation of indifferent phase equilibria

A straightforward iterative search for indifferent equilibria is described. It is applied to systems relevant to separation and production processes such as fractional distillation or crystallization and sintering. The respective G functions were taken from literature or obtained with the help of the optimization routine of ChemSage. The calculations for the localization of indifferent phase equilibria were also carried out with ChemSage, however, the new method operates independently of the computer software used.     

计算机硬件的It常维护

针对硬件故障发生的频率不断上升的现象,进行科学的日常维护与故障检修非常必要,本文对计算机硬件日常维护原则及如何做好计算机硬件日常维护进行了论述,提出了自己的思考。     

Design of a MUMPS interpreter

This paper describes the basic design of Comp Consultants Standards Mumps system for Tano Corporation's Outpost 11 6800 based micro computer running under the Flex 2.0 floppy disk operating system with 64K bytes of random access memory. The Mumps system consists of an executive which includes I/O device handlers, and interpreter for Standard Mumps and a floppy disk storage system for global variables based on balanced trees with key compression by indexes and with 32 K of random access memory buffers to make up for the slow floppy disk access times. Comp Consultants Mumps involves some significant departures from previous Mumps implementations. In particular local variables and routine lines are stored in the same manner as global variables. For example the storage key for a routine consists of three parts: The routine name, a label, and a line offset number. Representing local variables and routines as global variables not only increases the available buffer space by eliminating special code to handle local variable storage, routine storage, and program editing; but also increases the utilization of the buffers by keeping in memory what is most often accessed regardless whether it is a local variable, a global variable, or program code. This unified representation of local variables and routines as global variables is described in detail in this paper.     

Computer-augmented preliminary design of aircraft wing structures

A computer system to aid in the preliminary design of aircraft wing structures for minimum weight is described. The system was developed to utilize effectively the best attributes of both computers and the human mind in the iterative process of analyzing highly redundant trial structures and using these results to select new trial structures with the objective of minimizing weight. The computer is used for the routine data processing, and the designer performs those tasks which require judgement and intuition. Cathode ray tube graphical displays are provided for checking input data and for evaluating results. From given basic information on the wing structure, loads, and material properties, a finite element model is developed, analyzed, modified to eliminate violations of design criteria, and optimized to obtain the structural configuration of least weight. The optimization proceeds automatically, but the designer may monitor progress with the aid of tabular and graphical displays and modify the direction in which the optimization is proceeding. The impetus for this work was provided by a need for such a system in teaching structural design to aeronautical engineering students. The modular system was developed for the Control Data Corporation 6400/6500 computer installation at Purdue University using the Purdue Interactive Remote Access Terminal Environment (PIRATE).     

Curved box beam bridge analysis

A finite difference procedure is used to determine the response of a single and multi span curved single box beam bridge with any number of interior diaphragms. The bending and torsional distortions as well as cross-sectional distortions are determined throughout the box girder. The forces that are determined include bending moment and shear, pure torsion, warping torsion, and bimoment. These forces, in addition to distortional functions, yield resulting normal bending, normal warping, and normal distortional stresses.The entire analysis scheme has been programmed for use on an UNIVAC 1108 computer, FORTRAN IV language, as given herein.     

Computer aided design of prestressed concrete highway bridges

The paper presents a computer aided design system for prestressed concrete highway bridges which, starting from few geometrical data, provides the complete geometry, prestressing steel, reinforcing steel, amount of materials and cost of all the bridge elements: deck, bearings, piers, abutments and foundations. Different configurations are devised, from short and medium to long-span bridges, accounting for different deck super-structures and erection methods. All the results are displayed on the computer screen and can be printed. The system provides also DXF files containing the general layout, cross-sections and prestressing arrangement of box girder bridges. This system allows, in a short time, an accurate design and an economical estimation of a particular bridge, taking into account the most important technical requirements. It is a useful decision-making tool for both design and administration engineers.     

The idealized structural unit method and its application to deep girder structures

An efficient method of analysis of non-linear behavior until collapse of large size redundant structures is presented. The method is named as The “Idealized Structural Unit Method”. In this method the structure is divided into the biggest possible “Structural Units” whose geometric and material nonlinear behavior can be idealized and described in a concise analytical-numerical form. The structure is reassembled and load is applied incrementally until ultimate strength is attained.In this method, modeling is an obvious operation of dividing the structure into its actual structural units. This eliminates the effort required for the choice of type of element or size of mesh as in the finite element method. The number of structural units and overall degrees of freedom required for the analysis of a structure by this method are less in order than the number of elements and overall degrees of freedom required to analyze the same structure by the FEM. Costs of computer and data preparation may be drastically reduced.Application of the method to metal structures built up of deep I girders, such as bridge girders, ships deep girders and grillage structures is considered. The “Girder Structural Unit” is defined and its behavior under increasing loads is idealized based on existing as well as newly developed theoretical and experimental studies. Conditions for web bucking, ultimate strength and full plastic strength are established and expressions for stiffness during various stages are derived. A deep girder structure may then be treated as an assembly of such “Girder Structural Units”. Results of analysis of example structures are presented. The consumed computer time is found to be very short, as expected. Comparisons with results of experimental studies show good agreement.