17.13.1 Plant and Equipment
The suitability and capacity of all plant and equipment used for erection shall be to the satisfaction of the engineer.
17.13.2 Storing and Handling
All structural steel should be so stored and handled at the site that the members are not subjected to excessive stresses and damage by corrosion due to exposure to environment.
17.13.3 Setting Out
The positioning and levelling of all steelwork, the plumbing of stanchions and the placing of every part of the structure with accuracy shall be in accordance with the approved drawings and to the satisfaction of the engineer in accordance with the deviation permitted below.
17.13.3.1 Erection tolerances
Unloaded steel structure, as erected, shall satisfy the criteria specified in Table 33 within the specified tolerance limits.
Each criterion given in the table shall be considered as a separate requirement, to be satisfied independent of any other tolerance criteria. The erection tolerances specified in Table 33 apply to the following reference points:
- a) For a column, the actual centre point of the column at each floor level and at the base, excluding any base-plate or cap-plate. The level of the base plate on pedestal shall be so as to avoid contact with soil and corrosive environment; and
- b) For a beam, the actual centre point of the top surface at each end of the beam, excluding any end-plate.
| SI No. | Criterion | Permitted Deviation |
|---|---|---|
| (1) | (2) | (3) |
| i) | Deviation of distance between adjacent columns | 5 mm |
| ii) | Inclination of a column in a multi-storey building between adjacent floor levels | 0.002hs where, hs is the storey height |
| iii) | Deviation of location of a column in a multi-storey building at any floor level from a vertical line through the intended location of the column base | 0.0035 Σ hb/n0.5 where, Σ hb is the total height from the base to the floor level concerned and n is the number of storeys from the base to the floor level concerned |
| iv) | Inclination of a column in a single storey building, (not supporting a crane gantry) other than a portal frame | 0.0035hc where, hc is the height of the column |
| v) | Inclination of the column of a portal frame (not supporting a crane gantry) | Mean: 0.002hc Individual: 0.010hc where hc is the height of the column |
The straightness tolerances specified in Table 34 have been assumed in the derivation of the design stress for the relevant type of member. Where the curvature exceeds these values, the effect of additional curvature on the design calculations shall be reviewed.
A tension member shall not deviate from its correct position relative to the members to which it is connected by more than 3 mm along any setting axis.
17.13.4 Safety During Fabrication and Erection
17.13.4.1
All steel materials including fabricated structures, either at fabrication shop or at erection site, shall be handled only by a worker skilled in such jobs; where necessary with load tested lifting devices, having
tested wire rope slings of correct size. The devices should be well maintained and operated by experienced operators.
Table 34 Straightness Tolerances Incorporated in Design Rules
(Clause 7.13.3.1)
| Sl No. | Criterion | Permitted Deviation |
|---|---|---|
| (1) | (2) | (3) |
| i) | Straightness of a column (or other compression member) between points which will be laterally restrained on completion of erection | 0.001L generally, and 0.002L for members with hollow cross-sections; where, L is the length between points which will be laterally restrained |
| ii) | Straightness of a compression flange of a beam, relative to the weak axis, between points, which will be laterally restrained on completion of erection | 0.001L generally, and 0.002L for members with hollow cross-sections; where, L is the length between points which will be laterally restrained |
17.13.4.2
Oxygen and acetylene cylinders and their hoses shall have distinctive colours. Cylinders should be stored in upright position in well-ventilated rooms or in open air, not exposed to flames, naked lights or extreme heat and should also be in upright position when they are being used. All gas cutting works shall be done only by experienced skilled gas cutters, equipped with gloves, boots, aprons, goggles and good cutting sets of approved make.
17.13.4.3
While doing any welding work, it should be ensured that the welding machine is earthed and the welding cables are free from damage. The welder and his assistant shall use a face shield or head shield with a welding lens and clear cover glass and their hands, legs and bodies shall be well protected by leather gloves, shoes and aprons. Combustible materials should be kept away from the sparks and globules of molten metals generated in any arc welding. In case of welding in a confined place, it should be provided with an exhaust system to take care of the harmful gases, fumes and dusts generated.
17.13.4.4
In addition to precautions against all the hazards mentioned above, erection workers shall also be protected in the following manner:
- a) All workers shall wear helmets and shall also be provided with gloves and shoes. In addition those working at heights shall use safety belts.
- b) All structures shall be so braced/guyed during erection that there is no possibility of collapse before erection work is completed.
- c) Warning signs such as 'Danger', 'Caution'
'440 volts', 'Do not smoke', 'Look ahead' etc; should be displayed at appropriate places.
17.13.4.5
For detailed safety precautions during erection, reference shall be made to IS 7205.
17.13.5 Field Connections
17.13.5.1 Field riveting
Rivets driven at the site shall be heated and driven with the same care as those driven in the shop.
17.13.5.2 Field bolting
Field bolting shall be carried out with the same care as required for shop bolting.
17.13.5.3 Fillet welding
Field assembly and welding shall be executed in accordance with the requirements for shop fabrications excepting such as manifestly apply to shop conditions only. Where the steel has been delivered painted, the paint shall be removed for a distance of at least 50 mm on either side of the joint.