Specification Part 3 - Road & Bridge Works - Urban Administration ...

2003.2. Construction Operations
a) All work shall conform strictly lo the drawings and shall be in accordance with the provisions of this
section. Care shall be taken lo ensure that all parts of an assembly fit accurately together. The
workmanship shall satisfy all relevant provisions laid down in Section 1900.
b) Knuckle pins, rolling surf aces of the rollers and bearing surface of the bearing plates shall be
machined and all boll holes shall be drilled. The whole bearings shall be fitted and finished as
required for good quality machined work to the satisfaction of the Engineer. However, in case of
bearings which arc to be grouted or bedded on a suitable yielding material on any surface which is
to be in permanent contract with the grout or the yielding material may be left unmachined.
c) In prestressed concrete construction where launching of girders is employed, in order to avoid
slipping or jumping of rollers due lo vibration or jolts, adequate measures may be taken to ensure
that the roller assembly is not disturbed. It is normal practice lo provide rocker bearings on the
bunching end and place the beam on Iris rocker end slightly in advance of placing on the roller.
d) During concreting of girders, the bearings shall he held in position securely by providing temporary
connection between the top and bottom plates in cast of fined bearings and between top plate,
base plate and saddle plate in case of roller cum-rocker bearing or by any other suitable
arrangement which prevents the relative displacement of the components.
e) In prestressed precast girders, where recesses arc left on the underside of girders receive the
anchor bolts, grout holes extending to the beam sides or to the deck level shall be provided. The
cement sand grout shall have a mix of 1. 1
2003.3. Workmanship
a) Fabrication shall be carried out by an organization experienced and qualified in undertake precision
engineering of this type and be approved by the Engineer
b) Workmanship shall be of good quality, neatly finished and of good appearance
c) Castings shall be true to the forms and dimensions shown on the drawings and stall be free from
pouring faults, sponginess, cracks, blow holts and other defeat on position, affecting their
appearance or strength Warped or distorted castings will not be accepted. Exposed surfaces shall
be smooth and dense.
d) All castings shall be cleaned by sand or shot blasting to remove sand or scale and to present to
clean uniform surface.
e) All irregularities fins or risers shall be ground off flush with the adjacent surface. Castings with
visible cracks, blow holes or similar blemishes shall be rejected if the imperfections are located in
bearing surface or cannot be remedied to the approval of the Engineer.
f) Imperfections which are not located in bearing surface shall be cleaned out, filled with weld metal of
the appropriate composition and ground flush.
g) All surfaces of major components like top plates, saddle plates, base plates, rollers of the bearings
shall be machined all over for correct alignment, interchangeability, proper fittings, etc.
2003.4. Tolerances
Tolerances for its individual components or of the assembled bearings shall be as shown on the
drawings or subject to the approval of the Engineer.
Unless otherwise specified, the following tolerances shall be maintained:
Diameter of Rollers, Knuckle Pins and Bores
Tolerances on diameter of rollers and all convex surfaces s hall conform lo K7 of 15:919.
Tolerances on diameter of all concave surfaces shall conform 10 D8 of IS: 919.
Height of Bearings