OCR Text |
Show BITOiflJfllFWIf1 ffilw? ilMl1 B ;;y.:-, , y:n .... .,rf4gjy H FOR CULVERTS AND BRIDGES B tool anc Concrete Combined Conetl H tuts Form of Construction Eco- H' nomlcal and Durablo. B (By C. H. MOOUFIEL.D.) BH A combination or atoel and conoroto B made In such a manner that oaoh ma-1 B terlal will bo required to withstand B tho chnrnctcr of atrcBB for which It la B host adapted that Is, tension for stool B and compression for concrete conatl-; B tato a form of construction for Bhortj B bridges and culvorts both economical B and durable. The advantages of the B two materials aro combined and their B . disadvantages In a large degree ellml B natcd. B ThlH form of construction, on ac-( B count of its economy and simplicity, Ibi B especially well suited to highway cul-' BH verts and Bhort spun bridges, whon fori H any reason It la deslrablo that their, B superstructures bo kepi flat. In the; H oaso of arch culverts and bridgos built1 BBBW BBBHBuSflESflBVHBBflBaBBflBVFBBBBBBV ' BBf I BBBMiBiCiBWi i m'liaflijfliiiii i if iii.iw in d I n, IT1 trfTrt TP ! BB Reinforced Concrete Culvert on a Mai- H sachusetts State Road. H of concroto tho economy of Introduce BB Ing ateol is not always evident and, BB should bo demonstrated In any partic- H ular case before It Is decided that the- BB arch must be reinforced. m The conditions to bo met In the con- Btruotlon of reinforced concrote cul- H verts make It deBlrable, from a stand- m pohit of economy, that a relatively m high grade of concrete b UBed. Any BB" decrease? fa the atrenxth of, tae cob- BB crete necessitates a coreBfoadlag la- BB crease In come dimension ef the mem- H, bora, and thereby adds to the dead H load which the structure must sustain. BB Reinforcing bars should be mado H from steel having a safe strength of M no less than 16,000 pounds per square BB Inch, and should possess Bufilclcnt. BB malleability to bo readily bent Into the BB desired Rhapes while cold. When BB plfced In concrote they should be free Hx from rqBt, grease or foreign materials M of any kind' otherwise a perfect bond H botweon tho bare and the concrote will BB not bo obtained. H ..Deslgnero of highway bridgo and BB drainage structures are urged not only BB to investigate the safety and dura' blllty of proposed designs, but to con- 1 aider their esthetic features as well. m ' When bridgos and culverts ore to be BB constructed of pormanont materials, BB such as reinforced concroto, the de- m signer ehould bear constantly In mtitd BB tho fact thnt any esthetic defects M which may be present in such struc- BBJ turos will bocome more and moro ap- BB parent as the community develops. BB For example, a highway brldgo, the BB defects of which are hardly noticeable BB when tho highway on each sldo 1b bor- BB dbrod by dilapidated fences and build- BB lngs may become u veritable eyesore BBBBBWi BSBSBBBBBBfflHRsK?BBWBBBrnBBSBnBBBBBBI bbbbbbI PBnrer fiiti-'Mii ffiiH MsssssssW HBsSl &m WBH?P ' Ff im ' r ' ' r r TirSSSSSSSSi ssssssa ssssssssssc?iifeirissasssss? ?'' x?itsHiSSSSj SSSSSSm JSm'BSSSTSKHtSSBSw'SKMSiASSSKBSSaHBSSB BBBBbV' SSSSSSlSSBSffiiBvBsSSSHHflaSBBSSSSK 1 Concrete Arch Bridge In tho District M of Columbia. B if these features of tho landscape aro m Bufflclently Improved. A ddalgn may H be In excellent taate, however, and M yet bo almost totally dovold of orna- H mentation. A few simple panels and B copings aro usually aufllclent to lend H an attractive appearance to masonry M bridges, provided tho planes of the M wing walls, parapota, etc., ar la H proper relation to each other and 'to H the roadway. |