Show FOR AND BRIDGES steel and concree combined consal tute form of construction economical and durable ny C it II A co combination in aon of steel and concrete I 1 made ad 1 in uch buch a manner that eich each ma aerial will bp bf required to withstand the character of stress for which it is best adopted adIli ted that Is tension for or steel and compression for concrete conati tuto tute a form of 0 construction for short budges bridges and cull culi errs erts both economical and durable the adian of the two tro materials mater lils are combined and their disadvantages advantages dle in a large degree elaml bated this form of construction on ac count of its economy econom rind and simplicity Is especially well suited to cul verts and short span bridges when for any reason it Is desirable that their superstructures be kept nat flat in the case of arch cu ru lverts and bridges s built IV M lot ifa ma ak ralz Z 15 reinforced concrete culvert on a mae eachus etts state road of 0 concrete the economy of 0 Int introduce Intro duc ing steel Is not always evident and should be demonstrated in any partle ular alar case before it Is decided that tho the arch must be reinforced the conditions to be met in the con of reinforced concrete con creto on cul verts make it desirable from a stand point of 0 economy that a relatively nigh high grade of concrete be used any decrease in the strength of the con crets crete necessitates a co responding in cress crease e in some dimension of the mem bers and thereby adds to the dead load which the structure must sustain reinforcing bars should be made from steel having a safe strength of D pot of less than 16 pounds per square inch and should possess sufficient malleability to be readily bent into the desired shapes hile cold when placed in concrete they should be tree free from rust grease or foreign materials 0 of an kind otherwise a perfect bond between the bare and the concrete N will III not be obtained designers of highway bridge and drainage structures are urged not only to investigate the safety and durability ot of proposed designs but to con sider elder their esthetic features as well viell when bridges and cul culverts cu lverts are to be ba constructed of perman permanent erit materials such as reinforced concrete the de signer should bear constantly in mind the fact that any esthetic defects which may be present in such tures will become more and more apparent as the community develops for example a highway bridge tho the detects defects of which are hardly noticeable when the highway on each side Is be bordered by dilapidated fences and buildings may become a veritable eyesore 4 T A 04 9 az i tiA i iw iata y s j kiwy ifft i 1 1 t 4 IP y WM w i A s ajai f y V concrete arch bridge in the district of columbia it if these features of the landscape are sufficiently improved A design may be ba in excellent taste however and yet be almost totally devoid deold of orria orna A few simple panels and copings are usually sufficient to lend an attract attractive he appearance to masonry bridges provided ded the planes of th the s wing walls parapets etc are i in n proper relation to each other and to the roadway |