Transactions of the American Society of Civil Engineers

The purpose of this paper is to extend the analysis of the ring of a skew arch that was given in a previous paper to include skew arches of more than one span and, by placing the skew equal to zero, to show how this method may be applied to the multiple right arch on elastic piers. In this latter case, the effect of eccentric loads is brought out by the formulas. With the idea of being consistent with the method of analysis used in the first paper, the simple method of deflections was retained instead of using one of the more elegant methods, such as virtual work, or a procedure of a similar nature. In order that this paper may be more complete in itself an outline of the method of analysis of the single-span skew arch will be reviewed briefly. For the derivation of the formula for the deflection of a skewed cantilever under the various loads used, reference should be made to the previous paper.

The Symposium on “Equitable Distribution for Highway Purposes of Motor Vehicle Licenses and Gasoline Taxes,” conducted by the Highway Division of the Society during 1929, brought out the status of contemporary practice and opinion representative of the various governmental jurisdictions interested. The papers and discussions presented in this Symposium disclosed the fact that engineers in general concur in three basic principles. In this paper the writer discusses from an engineering point of view, and without prejudice, some of the factors that appear to have a controlling effect in the equitable assessment of highway costs, and calls attention to some research projects that could aid materially in ascertaining the facts that are needed. These facts themselves will vary from place to place and from State to State, but the same methods of attack upon the problem should result in some uniformity in procedure.

The object of this paper is to present an exact theory for the design of large pipe lines and their supports, which may also be used for the design of horizontal tanks, under-water tubes supported on piers, etc. Instead of the saddles commonly used, the pipe is supported and kept in shape by full ring girders which were first introduced in Sweden. The ring girders act as stiff, disk-shaped members, preventing large distortions over the supports and their transmission into the pipe shell proper. Under these conditions stresses can be analyzed by the modern elastic theory of thin shells. It is found that the shell then is mainly subject to direct beam and ring stresses, the loads being transmitted to the supporting rings by shearing stresses. A narrow zone of secondary bending stresses occurs in the shell portions adjacent to the supporting rings, induced by the restraining action.

The aim of construction management is to conduct operations properly in the least expensive way, whether the task be to construct a bridge, lay a pavement, or move cubic yards of earth. In its broadest sense such management should begin with the consideration of the economic necessity and priority of procedure.

Management of construction work may well be classified into two departments: (1) The objective art of bidding for the contract, planning the work, and bringing it to completion; and (2) the subjective art of combining the elements in Part (1) to discover leaks in profit due to avoidable time losses in the various steps involved. This paper is confined to the first of these departments. Standards of success in conservative bidding are discussed, as are also the ideal qualifications of the most important men on any job, namely, the superintendent, master mechanic, and the foreman. The paper deals, specifically, with the best attitude to hold concerning the maintenance of a construction schedule.

In the fall of 1925, Charles Terzaghi, M. Am. Soc. C. E., joined the staff of Massachusetts Institute of Technology for the purpose of inaugurating advanced courses and establishing a program of extensive research in the field of Soil Mechanics. Under his direction a great amount of pioneer work was carried on, which served firmly to establish the importance of research in foundation engineering and allied subjects, and to define clearly the most promising lines of endeavor. It is the purpose of this paper to summarize briefly the salient elements of this work. The problems described fall into two main groups: (1) Soil Physics, comprising studies of the composition and grain distribution of soils, permeability, compressibility, consolidation, compressive strength, internal friction, and cohesion; and (2) Soil Engineering, including investigations on the bearing capacity and settlement of foundations, on hydraulic-fill dams, on the frost heaving of highway sub-grades, and on the lateral pressure of earth against retaining walls.

Locks, dams, and power houses along the Illinois Waterway in the State of Illinois constitute the primary subjects of this paper. A general description o:f the structures at Lockport, Brandon Road, Dresden Island, Marseilles, and Starved Rock, is followed by a theoretical analysis of culvert valve chambers, operating machinery, etc., as designed for this project. The steps in the design of miter-gates are reviewed briefly, including a description of a metal sealing-spring plate which permitted a more accurate and a lighter design. The gate anchorages were planned so as to make possible a fine adjustment of the rotation axis, similar to the arrangement for the locks at Sault Ste. Marie, Mich.

This paper deals specifically with the Kittitas Division of the Yakima Project, in the State of Washington, constructed by the United States Bureau of Reclamation. All irrigation projects undertaken by the Bureau are similar in character, although new ideas of design and new methods of construction are introduced in each new structure. Most of the structures on any one project are small in size, but generally the topography of the ground and the type of structure are such that the method of constructing each unit must be different from any other. There is a great variety in size and type of structures. The choice of a method of construction is placed in the hands of the contractors, subject to the approval of the engineers. In the case of small units, it is uneconomical to install elaborate and expensive set-ups of machinery.

Formulas are derived for the changes of water pressures during an earthquake for the case of a straight dam with a vertical up-stream face. The vibrations in the earthquake are assumed horizontal in a direction perpendicular to the darn. A formula is obtained involving a series of sines (Equation (31)). This series, however, may be replaced with satisfactory approximation by a simpler formula (Equation (49)). The results are also expressed in the following manner: The pressures are the same as if a certain body of water were forced to move back and forth with the dam while the remainder of the reservoir is left inactive; Fig. 3 shows approximately the shape of this body of water. The influence of the dynamic action of the water is found to be neither excessively large nor negligible.

The field of Western highway construction is so widespread and each locality offers so many varied problems that it is only possible to cover a small part of it. The writer, therefore, does not propose to cumber the already voluminous literature of highway engineering with repetitive descriptions of problems or the methods used in the solution of problems already common to highway engineers from their own experience or reading. The paper contains an outline of the methods used in solving certain construction problems of a nature unusual to Eastern terrain and to indicate some of the controls which have been applied in the Western States to those forces of Nature which, unless properly curbed, are destructive to the works of Man.

In the development of modern highway systems there is a serious need for a low-cost secondary road that will accommodate a limited heavy traffic and an unlimited light traffic. In the western part of the United States a light type of asphaltic binder known as fuel oil has been successfully used to treat crushed aggregate. Whether mixed at a central pug-mill plant, or on the road itself, the costs are about the same, and the result has proved economical in first cost and maintenance charges.

An ever-present susp1c10n appears in the discussion of wire rope to the effect that the popular formulas for the estimation of the loss of strength due to bending may not be consistent with experiment. This can be settled only by holding the problem up to engineering and analytical scrutiny. This paper is a start along this path. New and more comprehensive formulas are presented, which may serve a useful purpose in bringing to light data and analyses of the problem that have not been published by those who have given their attention to the subject. Wire rope is one of the most used, and most abused, commodities of industry. Therefore, all its properties should be known, to the end that the public and the wire rope manufacturer may agree upon the increase in its cost, if necessary to provide for more safeguards in the selection of materials and in the process of manufacture, so that its performance may be predicted for a properly supervised service.

A chronological narrative of the planning, design, and construction of the bridge that crosses Lake Champlain from Crown Point, N. Y., to Chimney Point, Vt., is given in this paper. After an historical summary outlining the preliminary legislative steps necessary, the subjects of traffic counts, estimates, finances, and proposed toll rates are discussed. A comparison of various types of bridges studied for this crossing and the reasons for adopting the continuous truss type are presented, followed by a description of the finished bridge itself, surveying methods of field location, specifications, loadings, materials, concrete, etc. Construction problems encountered on the substructure and superstructure are treated under separate headings.

This paper is concerned with the erection, only, of steel bridges, and, in consequence, classification of the structures will be made more from a standpoint of the problems facing the erection engineer than from type of structure. The physical conditions at the site, time permitted for erection, particular season during which erection is to take place, quantity of river flow, and similar factors have a greater bearing on the way the structure is to be handled than the type of structure itself. In general, the construction plant for erecting a steel bridge is determined by the type and size of the bridge and the method by which it is to be erected. In consequence, the problems involved by the type and size, which determine the method of erection, will be discussed before the equipment necessary to develop this method of erection, is taken up.

This paper treats the specific problems encountered by the contractors in constructing the two tubes of the Fulton Street, East River Tunnels, in New York, N. Y. Useful information is given concerning the size and general types of equipment necessary and the manner of using it to the best advantage. The paper supplies a general picture of the contractor's power house, required on a job of this scope, and the assembly and erection methods of various phases of the work, especially the shields, are described in detail. The paper closes with an interesting account of construction problems met during the building of the High Street Station.

This paper is intended as a warning, especially on wind connections in which negative moments due to gravity loads are neglected. Very high stresses in the connection members may be relatively harmless in themselves, but dangerous as far as the tension rivets are concerned, especially under alternate loading, where a gradual loosening may result.

This paper begins with a general introductory statement of the relative advantages of aerial and ground-survey methods in topographic mapping. A discussion of the fundamental principles of stereoscopic measurements is given to prepare the reader for a better understanding of the mechanical features involved in the construction of measuring stereoscopes. A description is given of some of the instruments in use at present for making topographic maps from photographs taken in the air. The theory of the aerocartograph is described in detail because that is the instrument with which the writer is most familiar. However, it is intended that this description be considered merely the “ground work” for a general theory and that discuss ion will produce comments on similar instruments in so far as they vary from the aerocartograph, on the advantages and disadvantages of the various types, and on general suggestions for improvement based on experience.

Provided that State supervision of dams is to obtain, this paper contains recommendations upon the means to be taken for the regulation of design, construction, and maintenance. Characteristics of the best types, the extent, exemptions, personnel, and costs of supervision are discussed, and the paper concludes with comments on the feasibility of building codes for dams.

It is not the purpose of the writer to go into the question of the economics of dam construction, n or to discuss the many intricate, albeit fascinating, questions involved in theories of dam design, but rather to endeavor to discuss the subject more from the viewpoint of the public which, after all, is the party most vitally interested in the design, construction, maintenance, and operation of dams. This superior interest arises from two causes: First, that having to do with the element of hazard; and, second, that having to do with the economic advantages to be secured through the construction and operation of storage reservoirs. The paper contains a tabulated summary of 293 dams that have wholly or partly failed, and a classification of the causes of these failures; it also contains a general comment on existing laws in the various States, and a suggestion for framing a code for the design and construction of dams. Fifteen items are included in the paper to indicate subjects that should, or should not, be included in State supervision; twelve items portraying the advantages and disadvantages of State control of dams, and twelve items defining the ideal qualifications of supervising officials.

During the last decade there has been quite a development in the construction of long-span cantilever highway bridges; and a number of such structures have been designed in the writer's office. As the computations have always been made and recorded systematically, it was practicable to obtain weights of steel per linear foot of structure for the various divisions of the metal, namely, trusses, floor system, lateral system, anchorages, and on piers; and with these, by some established empirical formulas of transition, it was feasible to pass from known weights per foot in any layout to the corresponding weights per foot in a different but somewhat similar layout, and, in that way, and by means of moment-area diagrams, to determine all the economic functions for this type of highway bridge.

The usual type of transmission-line structure that supports high-tension lines across open country is of so frequent occurrence, that little comment is aroused when such a line is constructed, unless it is of unusual length or carrying capacity. Sometimes, however, the approach of a power line to the boundaries of a city requires the use of unusual types of supporting structures in the effort to minimize right-of-way costs and provide additional safety in regions where the damage attendant upon a failure of the line would be disastrous.

This paper presents the results of a study of stresses in buttress and gravity type masonry dams and develops formulas, for the analytical determination of stresses at any point on a horizontal section through dams. It is shown that the stress equations for Groups II and III become identical with the equations for Group I when the radius is infinite and the taper is zero, respectively. Examples of several section types are given.

The purpose of this paper is to present a rational analysis of the stresses occurring in a continuous reinforced concrete structure which, due to variations in moisture content and in temperature, is subject to linear expansions or contractions. Formulas and diagrams are given whereby the required reinforcement may be determined for any combination of the various agencies which produce volume changes. Although cracks in structures of this kind cannot be entirely avoided it is possible, through suitable reinforcement, to make the individual cracks exceedingly small. It is shown, however, that the ratio of steel to concrete required for this purpose is relatively high and, in many cases, it will be considered prohibitive.

Lateral forces, such as horizontal wind pressures, when acting on a suspension bridge are sustained by the cables and the stiffening trusses, which transmit the resulting reactions to the towers and abutments. The hangers which connect the trusses to the cables force the two loaded systems to work together so that the deformation on one system exerts its influence on the other. As soon as the bridge swings out of its vertical plane the effect of the dead and live load comes into action and tends to reduce the horizontal deflections. Consequently, a redistribution of the acting wind load follows until equilibrium is established between all acting forces.

The growth of the Welland Canal of 1829 to the Welland Ship Canal of 1931 represents a vast change in construction methods. Of the total cost of $130 000 000, about 60% was for earth and rock excavation and concrete. A description of the methods used in handling these three items of construction constitutes the body of the paper. The letting of contracts, the division of the work into sections, the labor force and rates, and the difficulties and delays occasioned by the World War, are discussed preliminary to methods and costs. In the study of costs it is to be borne in mind that they represent two periods of markedly different dollar values, namely, pre-war and post-war. The writer has provided extensive data showing the wide range of contract prices, but h as confined his information to field costs, leaving the reader to use his own preference in adding overhead and rental charges.

The paper here presented contains the derivation of analytical formulas for moments, thrusts, and shears in the inclined circular arches of multiple-arch dams. All the equations were derived by integration through application of the theorem of Castigliano, and they include the internal elastic work due to shear. As they are all necessarily long and cumber some, coefficients for obtaining moments, thrusts, and shears were computed, and curves representing these coefficients are presented for the convenience of the designing engineer. The water load on the arch may be divided into two parts, the first being the uniform water load due to the head measured from the free water surface to the arch crown, and the second, the variable water load which results from the inclination of the arch. In addition to the water load, the dead weight of the arch and the temperature stresses must be considered, and the moments, thrusts, and shears of all these influences must be combined algebraically to determine maximum stresses.

Fundamentally, the economic feasibility of hydro-electric development in connection with an irrigation project presents the same problems for consideration and is governed by the same limiting factors as any other hydroelectric development, with the exception that certain additional restricting considerations are introduced in the case of the combined development. This paper discusses these restrictions and propounds three fundamental principles to govern the engineer in judging the feasibility of combination. Eight basic essentials for a successful hydro-electric power system, and the fields most appropriate for the use of power in connection with an irrigation project are presented. Supporting illustrations are drawn from the Salt River Project in Arizona. Six conclusions are listed at the end of the paper.

This paper applies to the problem of pier extensions in the Hudson River west of the Island of Manhattan, the broad hydraulic principles of waterway design. It presents data indicating that successive encroachments on the navigable fairway by the extension of piers have set in action natural forces which have scoured the river bottom, actually increased the cross-section area at a substantial saving in dredging expense, and, contrary to generally accepted statements, have actually decreased tidal current velocities.

This paper outlines an accurate method of determining, from duration curves, the reliable power rate, and plant and reservoir capacities for a combination of hydro-electric plants and reservoirs on streams with similar flow distribution, but not necessarily in the same basin. The method can be utilized for these problems only by studying data for exactly one reservoir cycle. This procedure is fundamental, and may have been overlooked by other investigators; at least, no study has been found in which this factor has been emphasized.

The paper is a theoretical analysis of an arch dam that is intended to simplify present-day design methods and bring to light the proper relationship between the profile of the clam site and the shape of the arch dam. Conditions are investigated under which the dam can be relieved of unnecessary stresses. The compensate d dam that is introduced, carries the stresses due to dead weight and water load, but it is relieved from stresses due to contraction or expansion of concrete and deflections of the foundations and abutments. This investigation indicates a design that is believed to result in a safer and more economical structure.

The formation of the Special Committee on Steel Column Research was authorized in 1923. Its First Progress Report consisted of a study of existing test data, classified and analyzed as far as appeared to be practicable. The Second Progress Report gave the results of tests of eleven columns made with oblique loading, for the purpose of studying shearing stresses, tests of twelve columns under eccentric loading, and some tests on lacing-bars. This second report also contained a discussion of general matters pertaining to the strength of columns, including column formulas. Suggestions were also made as to further experimental work that seemed to be desirable. These suggestions included a study of effect of form, strength of lacing-bars, strength of outstanding flanges, effectiveness of batten-plates and diaphragms, and the conditions of a column in a structure as related to results of laboratory tests.