118 F. M. GUMMOW. 



produced in a loaded beam, and which in most cases exceeds 

 the shearing resistance of the comparatively small concrete 

 section of the web. 



Plate-beam constructions may present the following 

 features, viz. — 1. A space may be covered by a plate-beam 

 consisting of main beams and plates only. 



2. It may be advisable to place the main beams so far 

 apart that cross beams are necessary to lessen the spans 

 of the plates. 



3. In conjunction with this latter arrangement another 

 series of beams parallel to the main beams may be employed 

 so that the whole area becomes subdivided into squares, 

 the plate portion of which being supported on all four sides, 

 acts similarly to buckled plates. 



Columns of concrete-iron constructed to support the 

 plate beams, have the advantage over ordinary iron columns 

 that they allow a better connection between column and 

 beam. They are made in all shapes, solid or hollow, and 

 are fort ifled by vertical irons placed near the outer surfaces, 

 which irons are connected together by horizontal cross-ties 

 to form a skeleton framing which hoops the concrete and 

 prevents it from buckling and bulging. The concrete-iron 

 plate-beam constructions in conjunction with columns are 

 especially suited for heavily loaded floors of wide spans 

 and have on that account found a very extensive applica- 

 tion in warehouses, hotels, stores and industrial establish- 

 ments. The whole of the concrete is built in situ and forms 

 a well connected monolithic body, which considerably 

 increases the stability of the buildings. 



These constructions being of greater bulk and dead weight 

 than those of iron, makes them less sensitive to vibrations 

 from fast r.unning machines, or blows from falling bodies, 

 and observations show that the maximum oscillation of a 

 concrete-iron beam and the duration of such oscillation is 



