less than one-twelfth the diameter or the greatest lateral dimension of cross section, but never less than three-quarters of an inch. Wherever the core of a cast-iron column has shifted more than one-fourth the thickness of the shell, the strength shall be computed, assuming the thickness of metal all around equal to the thinnest part, and the column shall be condemned if this computation shows the strength to be less than required by this Code. Wherever blowholes or imperfections are found in a cast-iron column which reduces the area of the cross section at that point more than ten per cent., such column shall be condemned. Castiron posts or columns not cast with one open side or back, before being set up in place, shall have a three-eighths-inch hole drilled in the shaft of each post or column by the manufacturer or contractor furnishing the same, to exhibit the thickness of the castings, and any other similar sized hole or holes which the Commissioners of Buildings may require shall be drilled in the said posts or columns by the said manufacturer or contractor at his own expense.

Iron or steel shoes or plates shall be used under the bottom tier of columns to properly distribute the load on the foundation. Shoes shall be placed on top. (Id., sec. 112.)

§ 113. Double Columns.- In all buildings hereafter erected or altered, where any iron or steel column or columns are used to support a wall or part thereof, whether the same be an exterior or an interior wall, and columns located below the level of the sidewalk which are used to support exterior walls or arches over vaults, the said column or columns shall be either constructed double- that is, an outer and an inner column, the inner column alone to be of sufficient strength to sustain safely the weight to be imposed thereon, and the outer columns shall be one inch shorter than the inner columns, or such other iron or steel column of sufficient strength and protected with not less than two inches of fireproof material securely applied, except that double or protected columns shall not be required for walls fronting on streets or courts. (Id., sec. 113, rev. from L. 1882, ch. 410, § 485, as amend.)

§. 114. Party-Wall Posts.- If iron or steel posts are to be used as party posts in front of a party wall, and intended for two buildings, then the said posts shall be not less in width than the thickness of the party wall, nor less in depth than the thickness of the wall to be supported above. Iron or steel posts in front of side, division or party walls shall be filled up solid with masonry and made perfectly tight between the posts and walls. Intermediate posts may be used, which shall be sufficiently strong, and the lintels thereon shall have sufficient bearings to carry the weight above with safety. (Id., sec. 114, rev. from L. 1882, ch. 410, § 485, as amend.)

§ 115. Plates between Joints of Open Back Columns.--Iron or steel posts or columns, with one or more open sides

and backs, shall have solid iron plates on top of each, excepting where pierced for the passage of pipes. (Id., sec. 115, rev. from L. 1882, ch. 410, § 485.)

§ 116. Steel and Iron Girders.- Rivets in flanges shall be placed so that the last value of a rivet for either shear or bearing is equal or greater than the increment of strain due to the distance between adjoining rivets. All other rules given under riveting shall be followed. The length of rivets between heads shall be limited to four times the diameter. The compression flange of plate girders shall be secured against buckling, if its length exceeds thirty times its width. If splices are used, they shall fully make good the members spliced in either tension or compression. Stiffeners shall be provided over supports and other concentrated loads; they shall be of sufficient length as a column, to carry the loads, and shall be connected with a sufficient number of rivets to transmit the stresses into the web girders. If the unsupported depth of the web plate exceeds sixty times its thickness, stiffeners shall be used at intervals not exceeding 120 times the thickness of the web. (Id., sec. 116.)

§ 117. Rolled Steel and Wrought Iron Beams Used as Girders. When rolled steel or wrought iron beams are used in pairs to form a girder, they shall be connected together by bolts and iron separators at intervals of not more than five feet. All beams twelve inches and over in depth shall have at least two bolts to each separator. (Id., sec. 117.)

§ 118. Cast-Iron Lintels.- Cast-iron lintels shall not be used for spans exceeding sixteen feet. Cast-iron lintels or beams shall be not less than three-quarters of an inch in thickness in any of their parts. (Id., sec. 118, rev. from L. 1882, ch. 410, § 485, as amend.)

§ 119. Plates under Ends of Lintels and Girders.- When the lintels or girders are supported at the ends by brick walls or piers they shall rest upon cut granite or bluestone blocks at least ten inches thick, or upon cast-iron plates of equal strength by the full size of the bearings. In case the opening is less than twelve feet, the stone blocks may be five inches in thickness, or cast-iron plates of equal strength by the full size of the bearings, may be used, provided that in all cases the safe loads do not exceed those fixed by section 139 of this Code. (Id., sec. 119, rev. from L. 1882, ch. 410, § 485.)

§ 120. Rolled Steel and Wrought Iron Floor and Roof Beams. All rolled steel and wrought iron floor and roof beams used in buildings shall be of full weight, straight and free from injurious defects. Holes for tie rods shall be placed as near the thrust of the arch as practicable. The distance between tie rods in floors shall not exceed eight feet, and shall not exceed eight times the depth of floor beams twelve inches and under. Channels or other shapes, where used as skewbacks, shall have a sufficient resisting

moment to take up the thrust of the arch. Bearing plates of stone or metal shall be used to reduce the pressure on the wall to the working stress. Beams resting on girders shall be securely riveted or bolted to the same; where joined on a girder, tie-straps of one-half inch net sectional area shall be used, with rivets or bolts to correspond. Anchors shall be provided at the ends of all such beams bearing on walls. (Id., sec. 120.)

§ 121. Templates under Ends of Steel or Iron Floor Beams.- Under the ends of all iron or steel beams where they rest on the walls, a stone or cast-iron template shall be built into the walls. Templates under ends of steel or iron beams shall be of such dimensions as to bring no greater pressure upon the brickwork than that allowed by section 139 of this Code. When rolled iron or steel floor beams, not exceeding six inches in depth, are placed not more than thirty inches on centres, no templates shall be required. (Id., sec. 121, rev. from L. 1882, ch. 410, § 484, as amend.)

§ 122. Framing and Connecting Structural Work.- All iron or steel trimmer beams, headers, and tail beams, shall be suitably framed and connected together, and the iron or steel girders, columns, beams, trusses and all other iron work of all floors and roofs shall be strapped, bolted, anchored and connected together, and to the walls.

All beams framed into and supported by other beams or girders shall be connected thereto by angles or knees of a proper size and thickness, and have sufficient bolts or rivets in both legs of each connecting angle to transmit the entire weight or load coming on the beam to the supporting beam or girder. In no case shall the shearing value of the bolts or rivets or the bearing value of the connection angles, provided for in section 139 of this Code, be exceeded. sec. 122, rev. from L. 1882, ch. 410, § 484, as amend.)

(Id.,

§ 123. Riveting of Structural Steel and Wrought Iron Work. The distance from centre of a rivet hole to the edge of the material shall not be less than:

5% of an inch for 1/2-inch rivets. % of an inch for 5%-inch rivets. 1% of an inch for 4-inch rivets. 1% of an inch for %-inch rivets. 11⁄2 of an inch for 1-inch rivets.

Wherever possible, however, the distance shall be equal to two diameters. All rivets, wherever practicable, shall be machine driven. The rivets in connections shall be proportioned and placed to suit the stresses. The pitch of rivets shall never be less than three diameters of the rivet, nor more than six inches. In the direction of the stress it shall not exceed sixteen times the least thickness of the outside member. At right angles to the stress it shall not exceed thirty-two times the least thickness of the out

side member. All holes shall be punched accurately, so that upon assembling a cold rivet will enter the hole without straining the material by drifting. Occasional slight errors shall be corrected by reaming. The rivets shall fill the holes completely; the heads shall be hemispherical and concentric with the axis of the rivet. Gussets shall be provided wherever required, of sufficient thickness and size to accommodate the number of rivets necessary to make a connection. (Id., sec. 123.)

§ 124. Bolting of Structural Steel and Wrought Iron Work.- Where riveting is not made mandatory connections may be effected by bolts. These bolts shall be of wrought iron or mild steel, and they shall have United States standard threads. The threads shall be full and clean, the nut shall be truly concentric with the bolt, and the thread shall be of sufficient length to allow the nut to be screwed up tightly. When bolts go through bevel flanges, bevel washers to match shall be used so that head and nut of bolt are parallel. When bolts are used for suspenders, the working stresses shall be reduced for wrought iron to 10,000 pounds and for steel to 14,000 pounds per square inch of net area, and the load shall be transmitted into the head or nut by strong washers distributing the pressure evenly over the entire surface of the same. Turned bolts in reamed holes shall be deemed a substitute for field rivets. (Id., sec. 124.)

§ 125. Steel and Wrought Iron Trusses.- Trusses shall be of such design that the stresses in each member can be calculated. All trusses shall be held rigidly in position by efficient systems of lateral and sway bracing, struts being spaced so that the maximum limit of length to least radius of gyration, established in section 111 of this Code, is not exceeded. Any member of a truss subjected to transverse stress, in addition to direct tension or compression, shall have the stresses causing such strain added to the direct stresses coming on the member, and the total stresses thus formed shall in no case exceed the working stresses stated in section 139 of this Code. (Id., sec. 125.)

§ 126. Riveted Steel and Wrought Iron Trusses. For tensioned members, the actual net area only, after deducting rivet holes, one-eighth inch larger than the rivets, shall be considered as resisting the stress. If tension members are made of angle irons riveted through one flange only, only that flange shall be considered in proportioning areas. Rivets to be proportioned as prescribed in section 123 of this Code. If the axes of two adjoining web members do not intersect within the line of the chords, sufficient area shall be added to the chord to take up the bending strains. To bolts shall be used in the connections of riveted trusses, cepting when riveting is impracticable, and then the holes all be drilled or reamed. (Id., sec. 126.)

$127. Steel and Iron Pin-Connected Trusses.- The bendng stresses on pins shall be limited to 20,000 pounds for

steel and and 15,000 pounds for iron. All compression members in pin-connected trusses shall be proportioned, using seventy-five per cent. of the permissible working stress for columns. The heads of all eye-bars shall be made by upsetting or forging. No weld will be allowed in the body of the bar. Steel eye-bars shall be annealed. Bars shall be straight before boring. All pin-holes shall be bored true and at right angles to the axis of the members, and must fit the pin within one-thirty-second of an inch. The distances of pin-holes from centre to centre for corresponding members shall be alike, so that, when piled upon one another, pins will pass through both ends without forcing. Eyes and screw ends shall be so proportioned that upon test to destruction, fracture will take place in the body of the member. All pins shall be accurately turned. Pin-plates shall be provided wherever necessary to reduce the stresses on pins to the working stresses prescribed in section 139 of this Code. These pin-plates shall be connected to the members by rivets of sufficient size and number to transmit the stresses without exceeding working stresses. All rivets in members of pin-connected trusses shall be machine driven. All rivets in pin-plates which are necessary to transmit stress shall be also machine-driven. The main connections of members shall be made by pins. Other connections may be made by bolts. If there is a combination of riveted and pinconnected members in one truss, these members shall comply with the requirements for pin-connected trusses; but the riveting shall comply with the requirements of section 126 of this Code. (Id., sec. 127.)

§ 128. Iron and Other Metal Fronts to be Filled In.- All cast iron or metal fronts shall be backed up or filled in with masonry of the thicknesses provided for in sections 31 and 32. (Id., sec. 128.)

§ 129. Painting of Structural Metal Work.- All structural metal work shall be cleaned of all scale, dirt and rust, and be thoroughly coated with one coat of paint. Cast-iron columns shall not be painted until after inspection by the Department of Buildings. Where surfaces in riveted work come in contact, they shall be painted before assembling. After erection all work shall be painted at least one additional coat. All iron or steel used under water shall be inclosed with concrete. (Id., sec. 129, rev. from L. 1882, ch. 410, § 487, as amend.)

Part 23.- Floor Loads, Temporary Supports.

130. Floor Loads.-The dead loads in all buildings shall consist of the actual weight of walls, floors, roofs, partitions and all permanent construction.

The live or variable loads shall consist of all loads other than dead loads.

Every floor shall be of sufficient strength to bear safely the weight to be imposed thereon in addition to the weight