Design Tables Research Articles

Column Base Plate Design Table

The column base plate design procedure given in AISC ASD Ninth Edition manual1 differs considerably from the Eighth Edition manual. Additionally, the procedure contained in the first printing of the Ninth Edition manual has been refined in the later printings of the manual to incorporate improvements proposed by Thornton. These changes result in lighter base plates under certain conditions of loading and base plate geometry. The purpose of this paper is to provide a design table that includes AISC Ninth as well as Eighth Edition base plates, and to compare the two designs. The basis for the design method contained in the AISC manual has been discussed in detail by others, and will not be repeated here.

Evaluation of simplified calculation methods for structural fire design

Several simplified calculation methods have been developed for structural fire design. Their function is to bridge the gap between element classification according to design tables, which are often too coarse for practical work, and elaborate scientific computer codes, which remain inaccessible for normal users. The aim of this paper is to compare and evaluate existing analytical methods for fire design of structural elements made of reinforced concrete, structural steel or timber. The fundamentals of these methods are outlined and discussed with regard to fire load, thermal and mechanical high-temperature behaviour of the materials, thermal and mechanical analysis of cross-sections and structures, and safety concept. The existing methods are valuated taking into account different criteria, e.g. consistency, theoretical and experimental verification and applicability of the procedure and input data. The overall uncertainties and deviations from existing test results are determined and covered by a global safety margin.

Bringing Human Performance Data to the Design Table

Product design is often viewed as being a heterarchical and iterative process, possessing both systematic and chaotic qualities. However, a common denominator across all design activities is the access and utilization of information. In today's computer-aided design market, most of the available tools are narrowly focused on specific computational details for individual stages of design. Aids are needed to support information access and utilization during all stages of the design process. The application of human engineering and ergonomics data by designers is an increasingly challenging problem. Locating and understanding relevant information so that it can be applied to specific design issues is difficult given the abundance of existing and new data available. This is further complicated, in that the data are typically written to communicate research results to other human factors specialists. A new software product, Computer Aided Systems Human Engineering: Performance Visualization Subsystem (CASHE:PVS), is described which will assist the designer during the decision making process, maximizing creative and analytical abilities while minimizing costs due to design time and errors. The software contains several features to enhance the designer's ability to interpret and apply the human factors data available in the product. Phenomena descriptions in text, figures, and tables are combined with experiential information via simulations, animations, and audio. This provides the user a unique and rich understanding of human performance phenomena and how they relate to the design of new products.

Active and passive analog filter design: an introduction

This text introduces the theory and design of active and passive analog filters and emphasizes modern trends and applications. It includes an introduction to OTA (operational transconductance amplifier) and switched-capacitor filters. The book is designed to lead smoothly from basic background circuit theory into the details of modern analog filter theory. The treatment not only covers a study of the basic filter structures, but also introduces advanced topics including sensitivity, operational amplifier gain bandwidth effects and compensation. Its complete coverage of modern approximation allows students to study all types and enables comparative studies of different filter realizations because of the use of computers in filter design. Many computer methods are introduced, emphasizing design and applications. Special features of the text include detailed discussion of filter design tables; treatment of effects and compensation methods; modern active filter techniques; and a variety of end-of-chapter problems.

Prestress Losses in Partially Prestressed High Strength Concrete Beams

The results of a comprehensive parametric study on prestress losses in prestressed and partially prestressed high strength concrete beams are reported. Attention is focused on the influence of the partial prestressing ratio (from no prestressing to full prestressing) and the compressive strength of concrete, from 6 ksi (41 MPa) up to 10 ksi (69 MPa). Different beam cross sections, representing building and bridge girders with various spans and spacings, were studied. Additional parameters investigated include the strength and type of prestressing steel (stress-relieved of low-relaxation), the yield strength of reinforcing steel, the relative humidity of the environment and curing conditions (steam- or moist-curing). Time-dependent prestress losses were computed through an accurate time-step analysis procedure, which was implemented in a computer program. Conclusions and recommendations are drawn for use in design practice. The results are applicable to pretensioned as well as post-tensioned members. Proposed design recommendations are suggested to replace current lump sum design tables suggested in the AASHTO Specifications and the ACI 343R-88 report on analysis and design of reinforced concrete bridge structures.

Prismatic and Nonprismatic Slender Columns and Bridge Piers

An approximate second‐order hand‐calculation technique is presented for the analysis and design of cantilever compression members. Prismatic members with constant or nonconstant reinforcement, and nonprismatic members can be treated by this method. A linear approximation of the nonlinear moment‐curvature relationship is derived. The approximation accounts for the influence of the axial load on the stiffness of the column. Analysis and design equations are generated, and their formulation takes into account the effects of creep, foundation rotation, and out‐of‐plumbness. Design tables for different cross‐section and material properties are presented. Analysis and design examples are presented for prismatic and nonprismatic columns.

Design guidelines for steel arch supports in underground mining

Design tables and guidelines for steel arch supports made from open steel H-sections are presented. The tables record the load bearing capacities, obtained from numerical modelling results, for four different types of steel arches namely circular, semicircular, semicircular with straight legs and splay-legged. A wide range of parametric values was taken into account. Support diameters ranging from 2 to 8 m were considered. The leg-to-overall height ratio of the arch was varied between zero and 0.4. Splay leg angles of 5, 10 and 15° were also included. Interpolating functions are introduced to help calculate the load bearing capacity of a steel arch whose design parameters do not match exactly with those cited in the tables. The procedure is illustrated by numerical design examples.

Steady-state analysis and design optimization of an inductor-transformer resonant DC-DC converter

The authors present a closed-form steady-state analysis of an inductor transformer resonant DC-DC power converter. This efficient method of analysis, which directly predicts the steady-state characteristics of the circuit, is used to develop an optimal design methodology. Normalized optimum design tables and curves are derived. The optimization procedure is summarized and is illustrated by a design example. State plane analysis is used to show the important role of the circuit leakage inductances on the steady-state performance of the system. Experimental results obtained from a prototype converter are used to verify the analytical results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Dispersion in suspended growth systems

Correspondence is established between a bioreactor having a given dispersion number and the equivalent ideal reactors-in-series system. A numerical method is used to determine the effluent concentrations. Dimensionless quantities and computer techniques are used in the calculations. Design tables are given to determine the required hydraulic residence time for a reactor with a given dispersion number, when the inlet and required outlet conditions and the coefficients of Monod kinetics are known. Application of the theory to plug-flow reactors is demonstrated and the results obtained are compared with the analytical solution.

Ultimate strength of fillet welded connections loaded in plane

Fillet welded connections are frequently loaded eccentrically in shear with the externally applied load in the same plane as the weld group. While some current design tables are based on ultimate strengths, methods of analysis that incorrectly mix inelastic and elastic approaches are still used. These methods give conservative and variable margins of safety. Design standards generally use a lower-bound approach basing strengths on the longitudinal value neglecting, conservatively, the increase in strength for other directions of loading. The factored resistance of fillet welds, as a function of the direction of loading, is established based on ultimate strength expressions developed herein and using geometric, material variations, and test-to-predicted ratios reported in the literature. Factored resistances of eccentrically loaded fillet weld groups are established. These are basesd on the method of instantaneous centres, ultimate strengths, and the load–deformation expressions developed herein that are functions of the angle of loading. Also, statistical data on geometry, material variations, and the comparison of predicted strengths with the full-scale test results of others are used. Tables of design coefficients giving factored resistances for various eccentrically loaded fillet welded connections are developed. The coefficients, on the average, are essentially the same as those in current design tables. Key words: connections, design tables, eccentric, fillet welds, limit states, ultimate strength.

A numerical approach to activated sludge kinetics

Mass balance equations for biomass and substrate are numerically solved to determine the effects of different variables on suspended growth systems. Dimensionless quantities and computer techniques are used to express the results generally. Monod kinetics and reactors-in-series principles are applied to explain variations in axial dispersion and waste-water quality experienced in real systems. An attempt has been made to determine the effluent concentrations as a function of two parameters, i.e. a dimensionless time and a dimensionless substrate concentration (of the incoming waste-water). The computer results have been generalized in the form of design tables. An available approximate method for plug-flow reactors has been compared with the solution obtained in this way, and the resulting error has been demonstrated. In this study, results obtained from large numbers of reactors-in-series are reported to characterize plug-flow conditions. Performance of reactors subjected to varying degrees of axial dispersion will be stressed in a subsequent paper.

Hyperbolic Parameters for Compacted Soils

Finite element methods are being used more and more during design, in cases involving compacted soil‐structure interaction. In general, it is not practical to conduct extensive tests to obtain the compacted soil properties required by the finite element methods during the design phase. Alternatively, if finite element approaches are used for developing design tables, soil properties representative of typical soil types and compaction specifications are required. To provide the needed design soil parameters for a wide variety of soil conditions, laboratory testing is carried out on three soils: a sand, a silt, and a clay. These soils are prepared at density states ranging from loose to 95% of the maximum from the standard compaction tests [American Society for Testing and Materials (ASTM) D698, American Association of State Highway and Transportation Officials (AASHTO) T‐99]. The tests used to obtain the soil parameters are triaxial compression, isotropic compression, and one‐dimensional compression. A consistent set of soil design parameters are obtained by fitting test results to a hyperbolic soil model representing Young's modulus and bulk modulus as functions of stress.

Design parameters for multi-stage waste treatment

In this study a mutual correspondence is first established between a bioreactor having a given dispersion number and its equivalent series reactor system. A numerical method is then developed to determine effluent concentrations from this system. Effluent concentrations from an equivalent reactor series are expressed based on a plug flow reactor with the same inlet and outlet conditions. Dimensionless quantities and computer techniques are used to obtain the results generally. Design tables are given to determine the required hydraulic residence time for a reactor with a given dispersion number when the inlet and outlet conditions and the coefficients of the Monod kinetics are known.

The Results of Experiments on Seated Beam Connections

Seated beam connections have been used for many years. They have historically been designed by tabular methods, and this tradition was recently continued in the new LRFD Manual. The derivation of these design tables are discussed elsewhere and will not be repeated here. It should be noted that the tables have historically considered local yielding of the beam web under edge loading, the strength of bolts or welds, the yielding capacity of the seat angle and the normal detailing dimensions. The new AISC LFRD Specification includes the new equation (K1-5) which checks the beam web for crippling or buckling. In this paper, the term buckling is defined to mean a vertical crimping or crippling of the web due to the application of a concentrated load on the flange. This is a stability mode of failure rather than a web yielding failure as presently considered in ASD design (8th Edition Manual). Unlike a web yielding formula, it includes the depth and the flange thickness of the beam as variables. Table 1 summarizes LRFD beam web capacities according to Eq. (K1-5) and a 3-½ in. bearing length. It can be seen that there are cases where the tabulated unstiffened seat capacities exceed the beam web buckling capacity. Therefore, AISC funded a research program at the University of Washington to study these connections. This paper summarizes some of the results of this experimental program.

A Case Study in System Dynamics Optimization

This paper presents the use of optimization as a tool for policy analysis and design in system dynamics models, and presents a demonstration of its use on the ‘project model’ developed by G. P. Richardson and A. L. Pugh III in their book Introduction to System Dynamics Modelling with DYNAMO. The use of optimization to design parameters, table functions and new model structure is shown to produce a very significantly improved performance for this model compared to conventional approaches.

Design of odd‐degree linear‐phase sampled‐data bandpass filters with equiripple amplitude response

AbstractThis paper presents a novel approach for the design and synthesis of odd‐degree sampled‐data filters. Initially, an efficient iterative scheme is described for the construction of a class of selective linear‐phase distributed bandpass filters with equiripple passband loss response. Then, the filter's transfer function is synthesized using classical distributed circuit networks. Finally, the equivalent switched‐capacitor filter could be constructed. the resulting switched‐capacitor networks are completely insensitive w.r.t. parasitic capacitances, as well as having low Cmax/Cmin Design tables and an illustrative example are also given.

Hydraulic Performance of Concrete Block Chutes

ABSTRACT The hydraulic performance of concrete block lined chutes was studied in the laboratory using 1/12 scale models. Chutes of 3:1 and 6:1 slope with three overfall heights were tested at various ponded heads and tailwater levels. Standard head-discharge relationships were developed. Dimensionless Pi terms were used to de fine the hydraulic jump location relationship. This relationship was used to provide a hydraulic jump location design table for field use.

Design of Partially or Fully Composite Beams with Ribbed Metal Deck Using LRFD Specifications

A Hindu saying states, "One picture is worth a thousand words (numbers)." With this optic in mind, the design aspects of steel-concrete composite beams using the recently adopted LRFD specifications are analyzed critically and the significance of several parameters is brought out clearly. Charts are then constructed to facilitate the design of partially or fully composite beams using rolled-steel, wideflange sections of A36 steel or A572 Gr. 50 steel. The slab may be a composite metal deck slab with ribs perpendicular to the beam, a haunched slab or, simply, a flat soffit concrete slab. The charts cover both adequate and inadequate slabs. The charts provided are a valuable tool from the practical standpoint, and also familiarity with them should contribute to the students and young engineers overall feel of the composite beam design problem. The design charts given here complement the composite beam design tables provided in the LRFD manual.

Understanding Composite Beam Design Methods Using LRFD

A recommended source of information for an understanding of Load and Resistance Factor Design concepts is through the composite design sections of the LRFD Specification and LRFD Manual. Specifically, the structural engineer designing a shear-connected composite beam has a new tool in the Composite Beam Selection Tables published in Part 4 of the LRFD Manual. These tables allow the designer much more flexibility in the alternative selection process that leads to better reliability and design economy. To properly exploit these options, however, an understanding of the fundamental composite strength limit theory and the model from which the design tables were created is needed. A particularly attractive benefit is that preliminary design manipulation can proceed with no required information regarding the strength properties of the concrete. When discrete cost parameters of the variable material requirements are known, cost optimization is also feasible.

Columns: From Theory to Practice

A recommended source of information for an understanding of Load and Resistance Factor Design concepts is through the composite design sections of the LRFD Specification and LRFD Manual. Specifically, the structural engineer designing a shear-connected composite beam has a new tool in the Composite Beam Selection Tables published in Part 4 of the LRFD Manual. These tables allow the designer much more flexibility in the alternative selection process that leads to better reliability and design economy. To properly exploit these options, however, an understanding of the fundamental composite strength limit theory and the model from which the design tables were created is needed. A particularly attractive benefit is that preliminary design manipulation can proceed with no required information regarding the strength properties of the concrete. When discrete cost parameters of the variable material requirements are known, cost optimization is also feasible.