GRSE PORTABLE STEEL BRIDGES
GRSE is pioneer in manufacturing Portable Steel Bridges in India. Since last
40 years GRSE is involved in manufacturing this special type of bridge. The design
of this bridge was initially developed from original Bailey Bridge designed during 2nd
World War.
GRSE Portable Steel Bridges are designed on the unit construction principle,
the base unit being a 3.048 meter (10 feet) long bay. These bays, when assembled
together, create bridges of various lengths, in multiple of 3.048 m (10 ft).
The bridge is „through‟ type, having two main girders with the carriageway in
between. The main girder is formed from steel panels, made of high tensile steel, of
dimension 3048 mm (10 ft) (L) X 1448 mm (4 ft 9 in) (H) considering c/c. distance of
pin joints, since each panel is connected to its neighbor panel thro‟ pin joints. The
load carrying capacity of the side girders, depend on no. of panels and their
configuration in the girder. The construction of girder may be single or double
storied with one or more panels present in each storey depending on strength
required. The construction of bridge is again denoted by configuration of panels in
each girder e.g. SS, DS, TS, DD, TD etc, wherein 1st letter denotes no. of panel in
each storey & 2nd letter no of storied i.e. Single Single, Double Single, Triple Single,
Double Double etc. Sometimes chord reinforcement is added to top & bottom
chords of panel for increasing the strength of girder of a given configuration and is
denoted by SSR, DSR, DDR, TDR etc.
Portable Steel Bridges are broadly classified based on the number of lanes and
width of carriageway, as demonstrated hereunder.
Single Lane Standard Width – Carriageway width 3.320 meter.
Single Lane Extra Width – Carriageway width 4.250 meter.
Double Lane – Carriageway width 7.000 meter.
The girders are connected crosswise by transoms, which are supported at
bottom chord of lowermost panels of girders. Steel decks are laid over transoms to
form the carriageway.
The maximum clear span for a Single Lane portable bridge is presently 60.96
m (200 ft). The same for a Double Lane bridge is 48.77 m (160 ft). Span may be
extended to any length beyond the above with multi-span bridges.
GRSE offers a further variety of Portable Bridge for larger spans i.e. spans
beyond 61 m (200 ft). It is Portable Steel Suspension Bridge, which covers a range
from 61 m (200 ft) to 122 m (400ft). Both timber & steel deck versions are available.
The Portable Steel Bridges cover a wide range of load class as per IRC 6,
ranging from class 9R to class 70R (the heaviest class on Indian Roads). A chart is
furnished below on various bridges produced by GRSE for ready reference.
GRSE PORTABLE STEEL BRIDGES
SL TYPE OF BRIDGE ROADWAY IRC* LOAD MAX. SPAN
NO WIDTH (M) CLASS (FT)
1. STANDARD WIDTH SINGLE 3.32 (i) UPTO 30R 200
LANE BRIDGE (STEEL DECK) (ii) 40R 190
(iii)70R 140
2. EXTRA WIDE SINGLE LANE 4.25 (i) UPTO 30R 200
BRIDGE (STEEL DECK) (ii) 40R 180
(iii)70R 140
3. DOUBLE LANE BRIDGE (STEEL 7.00 70R 160
DECK) WITH 10‟ X 7‟ PANEL (NORMALLY)
CLASS 24 AS 400
4. SUSPENSION BRIDGE 3.277 PER BRITISH
MILITARY LOAD
CLASSIFICATION
* INDIAN ROAD CONGRESS
The Portable Steel Suspension Bridges are capable of carrying load upto class
24R. When reinforced, they are also capable of carrying single vehicle of max. 40
MT (for timber deck)/ 30 MT (for steel deck) load, one at a time.
A tentative delivery schedule for all types of bridges is indicated below.
SL TYPE OF BRIDGE SPAN EXPECTED DELIVERY
NO PERIOD
1. SINGLE LANE BRIDGE ALL 2 – 3 MONTHS
2. DOUBLE LANE BRIDGE ALL 6 - 8 MONTHS
3. SUSPENSION BRIDGE 240FT – 400FT 3 - 4 MONTHS
TYPICAL VIEW OF GRSE PORTABLE STEEL SINGLE LANE BRIDGES
PORTABLE STEEL BRIDGE STEEL SUSPENSION BRIDGE
GRSE PORTABLE STEEL BRIDGES
TYPICAL VIEW OF GRSE PORTABLE STEEL DOUBLE LANE BRIDGES
GENERAL DESCRIPTION
GRSE has successfully developed Double Lane Portable Steel Bridge to allow an
uninterrupted flow of high density traffic.
Mode of construction of this bridge is similar to GRSE Single Lane Bridge.
The bridge is also of the “through” type, the roadway being carried between two
main girders. The main girder is formed from steel panels of welded construction
3048 mm. (10 ft.) long x 2160 mm.(7 ft. 1 in.) high between pin holes, each panel
being pin jointed to its neighbor end to end. The load carrying capacity of the girder
can be increased by adding extra panels alongside and on top of the existing
panels. The panels put alongside are known as trusses while row of panel put on
top of panels is called storey. Girder made of three panels along side each other
and one set of three on top is known as triple truss, double storey (TD in short).
This construction can be reinforced by the addition of chord reinforcement to the
top and bottom of each truss. The reinforced construction is annotated by the
addition of the letter `R‟. Construction TD when thus reinforced is termed as TDR.
GRSE PORTABLE STEEL BRIDGES
Illustration on such constructions of bridge girders are shown hereunder. The
heaviest construction is termed as QDR (Quadruple Truss, Double Storey and
Reinforced).
Transom Panel / Girder
The girders are connected crosswise by transoms. These are long RSJs which rest
on the bottom chord of the panels, and carry the roadways superstructure. They are
tied to the panel chords by transom bolts and fix the trusses in position at the
required distance apart.
End posts, Male and Female, are provided for connecting to the female and male
lugs at the ends of the panels of each truss of the bridge for distributing the shear
forces due to the end reaction of the bridge. The end posts attached to the ends of
each truss of bridge girder are supported on bearings which rest over base plates
placed on the ground at each end of the span. The base plates are intended to
spread the load from the bearings evenly over an area of ground.
Technical Specification
(a) Carriageway width – 7.0 m.
(b) Type of decking – Steel deck.
(c) Maximum span suitable upto IRC – 70 R load class – 160 feet.
GRSE PORTABLE STEEL BRIDGES
(d) Design verification done by IIT-Kharagpur through FE analysis.
(e) Materials: SAILMA 410 HI (Load bearing members).
(f) Advantages: - Portability
- Easy to erect.
- Temporary / semi permanent use.
- Modular, pre engineered, pre fabricated components.
- Manufactured in ISO 9001/2000 certified unit.
- Over 30 years experience of manufacturing and providing bridging
solution to BRO, State PWDs, PSUs and IPPs.
- Product is patented.
Method of Erection & Launching
The Portable Bridge is so designed that it can be completely erected on rollers on one side
of the gap to be bridged and then launched across without the use of any temporary support
within the gap. This is achieved by building on to the front end of the bridge a temporary
skeleton cantilever structure, called “Launching Nose”, which is constructed from the same
standard components as the bridge. To raise the skeleton Launching Nose up for facility of
landing on the far bank, a special component known as Launching Link is inserted in the
bottom chord of the Panels of the skeleton nose. The nose is built up of such a length that
when the whole structure is rolled forward, the tip of the nose lands on the rollers on the far
bank before the point of balance is reached. Once the bridge is in position across the gap the
Launching Nose is dismantled and the bridge jacked up of the rollers and lowered on to its
permanent bearings on the abutments.
Contact us at
Bailey Bridge Deptt.
GRSE Ltd.
61, Garden Reach Road,
Kolkata- 700 024.
Web site- www.grse.nic.in
Email- engg.gm@grse.co.in; engg.61p.agm@grse.co.in; grsebridges@yahoo.co.in
Phone- 033-2469-1177/1188/8140
Fax- 033-2469-1400
Mobile; 9831055426 / 9831307363