3.10.1
In view of the large number of factors involved in deciding the location, spacing and nature of expansion joints, the decision regarding provision of expansion joints shall be left to the discretion of the designer.
3.10.2
Structures in which marked changes in plan dimensions take place abruptly, shall be provided with expansion joints at the section where such changes occur. Expansion joints shall be so provided that the necessary movement occurs with minimum resistance at the joint. The gap at the expansion joint should be such that;
- a) It accommodates the expected expansion/contraction due to seasonal and diurnal variation of temperature, and
- b) It avoids pounding of adjacent units under earthquake. The structure adjacent to the joint should preferably be supported on separate columns but not necessarily on separate foundations.
3.10.3
The details as to the length of a structure where expansion joints have to be provided may be determined after taking into consideration various factors such as temperature, exposure to weather and structural design. The provisions in 3.10.3.1 to 3.10.3.3 are given as general guidance.
3.10.3.1
If one bay of longitudinal bracing is provided at the centre of the building or building section, the length of the building section may be restricted to 180 m in case of covered buildings and 120 m in case of open gantries (see Fig. 3).
Figure description:
- Entity: Structural building section schematic (referred to as Fig. 3.
- Total Length: 180 m.
- Layout: Six vertical bays/panels.
- Bracing: Cross-bracing (indicated by "X" marks is located at both end sections and the central bay.
FIG. 3 MAXIMUM LENGTH OF BUILDING WITH ONE BAY OF BRACING
3.10.3.2
If more than one bay of longitudinal bracing is provided near the centre of the building/section, the maximum centre line distance between the two lines of bracing may be restricted to 50 m for covered buildings (and 30 m for open gantries) and the maximum distance between the centre of the bracing to the nearest expansion joint/end of building or section may be restricted to 90 m (60 m in case of open gantries). The maximum length of the building section thus may be restricted to 230 m for covered buildings (150 m for open gantries). Beyond this, suitable expansion joints shall be provided (see Fig. 4).
3.10.3.3
The maximum width of the covered building section should preferably be restricted to 150 m beyond which suitable provisions for the expansion joint may be made.
3.10.4
When the provisions of these sections are met for a building or open structure, the stress analysis due to temperature is not required.
Figure description:
FIG. 4 MAXIMUM LENGTH OF BUILDING/SECTION WITH TWO BAYS OF BRACINGS
- Structure Components: A building section with multiple bays, featuring two specific bays with diagonal cross-bracings.
- Dimensions:
- Distance from the left edge to the center of the first braced bay: 90 m
- Distance between the centers of the two braced bays: 50 m
- Distance from the center of the second braced bay to the expansion joint: 90 m
- Key Feature: An Expansion Joint is indicated at the right boundary of the section.
FIG. 4 MAXIMUM LENGTH OF BUILDING/SECTION WITH TWO BAYS OF BRACINGS