Godavari Arch Bridge
Encyclopedia
The Godavari Arch Bridge also called the Kovvur
-Rajahmundry
Bridge, is a new bridge built across the Godavari River
in Rajamundry in Andhra Pradesh
, India and is the third bridge in the series of bridges that exist on the river in the state. The other two bridges located upstream of the new bridge are the Old Godavari Bridge
, a stone bridge known as the Havelock Bridge built by Sir Arthur Cotton in 1897 and parallel to it (since decommissioned), and the second railway bridge, a truss bridge, a functioning rail cum road bridge called the Godavari Bridge
.
This prestressed concrete
(PSC) arch bridge, made of bow-string girder arches or tied-arches, was built between 1991 and 1997. It was commissioned for passenger traffic in March 1997 and became fully operational for running trains by the Indian Railways
from 2003. The bridge is said to be one of the longest span PSC arch bridges in Asia, and maybe in the world.
The single-track railway bridge is designed to run trains at a speed of 160 miles (257.5 km) per hour and is designed to withstand wind speed of 200 miles (321.9 km) per hour during cyclonic storms that are anticipated at this location. The bridge is considered an outstanding example of expertise of the Indian Railways
in this field.
The bridge, built by the Hindustan Construction Company
, for the Indian Railways, was designed by M/S Bureau BBR, Switzerland and checked by M/S Leonard Andrea and Partners, Germany. The Indian Railways who built this bridge have stated that "It is perhaps for the first time anywhere in the world that a bowstring arch girder using concrete has been constructed for such a long span of 97.55 metres (320 ft), and that too for the Railway loading."
at over 1000 kilometres (621.4 mi) length) as it enters into the deltaic reach before debouching into the sea 60 kilometres (37.3 mi) downstream of the bridge, the second largest river in India. At the location of the bridge, near Rajamundhry, the river flows with a width of about 3 kilometres (1.9 mi), split in two channels with an island formation in between. The maximum discharge observed in the river is reported to be around 3 million m3/s and the maximum velocity of water flow as 5 metres (16.4 ft) per second. The rail-cum-road bridge is on the railway line between Chennai
and Howrah and connects the East and West Godavari districts in the state of Andhra Pradesh. The bridge is located in a cyclonic area where the wind speed could touch 200 kilometres (124.3 mi) per hour. There are two other bridges across the same river on the upstream. In the immediate upstream of the new Godavari Arch Bridge, is the Havelock Bridge or the Old Godavari Bridge, which was built in 1897 by F. T. G. Walton under the guidance of Sir Arthur Cotton. It has 56 spans of 45.7 metres (149.9 ft) each and is 2950 metres (9,678.5 ft) long made of masonry piers and steel girders. When constructed it was considered a marvel of British engineering. However, it has been decommissioned after commissioning of the new arch bridge. The second bridge is a rail-cum road bridge, planned in 1964, known as the Godavari Bridge which was sanctioned to double the track between Kovvur
and Rajahmundry, upstream of the new bridge and is functional. The road deck was added on demand from the public. It has 27 spans of 91.4 metres (299.9 ft) and 7 spans of 45.72 metres (150 ft) including 6 spans of 45.72 metres (150 ft)located on the 6° curve near the Rajahmundry end to negotiate the built up area in that reach.
be accepted. The firm had proposed the bowstring type concrete arch of span 92.552 metres (303.6 ft) with prestressed concrete box girder to act as tie. As this offer was found not only technically feasible but also financially acceptable, the order was placed on them to plan, design and build the bridge.
The final dimensions of the box girder are 95.462 metres (313.2 ft)×5200 millimetres (204.7 in) (bottom) with thickness of the top slab of 296 millimetres (11.7 in), the web of 300 millimetres (11.8 in) thickness and with the bottom slab thickness kept at 240 millimetres (9.4 in). A diaphragm stiffens the box girder at each Dina Hanger location. The substructure of the bridge consists of 28 piers. The bridge is located in two channels namely, the Kovvur channel and the Rajahmundry channel, and hence the bridge is also known as the Kovvur-Rajahmundry Bridge. The Rajahmundry channel has a deep rocky bed, and even the low water level is 18–20 m (59.1–65.6 ). However, comparatively the Kovur channel is shallow with a water depth of about 8–10 m (26.2–32.8 ) and river bed is made up of clayey deposits.
The box girder, which functions as the deck of the bridge and carries the live load, comprises end diaphragm (1000 millimetres (39.4 in) thick), which has inspection windows. The box girders are made of M42 grade concrete. Each girder is 95.552 metres (313.5 ft) long and was prestressed with 16 longitudinal cables, which in turn were prestressed to a force of 2950 kN each. (The BBRV system of prestressing was used for the permanent stressing of girder as well as temporary prestressing during construction under that bottom heading technique.) However, the bottom of the slab is provided with 24 lateral cables (two at each Dina Hanger location) which are also prestressed. In the stub part of the girder, six cables are provided laterally and duly prestressed. The flexing of the girders is directly linked to that of the arches, as the two are connected by hangers all along its length, at 12 locations. The design of the girder accounts for loading conditions of full span train load, half span train load, one third span train load and so forth with due accounting of temperature variation of ±10 °C (50 °F).
At each stage of casting of the girders (seven stages of casting were involved for each girder from girder stressing to removal of form work) forces generated in the arch section were studied and accounted, as required. The girder casting also ensured that no cracks appeared in the arches at any stage. Particular study was also done for the beginning part of the arch known as "starting stub", which has "distinct structural behaviour and has distinct function". Adopting a framework model, the stub was checked for cable force in temporary tendons as required for construction. The top deck slab was designed by analysis of "strip loads arising due to dispersion of axle loads through sleeper and ballast".
Each span of the bridge has 24 hangers, further divided under six types depending on their length. Each Dina Hangar is provided with 49 numbers of high tensile steel wires of 7 millimetre (0.275590551181102 in) diameter. The wires that run parallel to each other are encased in a high tensile polythene pipe, which is cement grouted. Based on detail analysis, the stress range for prestressing cables of the box girder was determined. The box girder was prestressed by "means of 16 longitudinal cables with a total force of 47177 KN and with lateral cables at each hanger location in the bottom slab."
Bearings
The bridge has been provided with pot bearings. On each pier, the girder is supported on four pot bearings of three types namely, the PNa type bearing (which facilitates free sliding in both directions) on one pier and PNe type (slides only in one direction) in the succeeding pier and PN type which is fixed type. The PNa and PNe type of bearings have been pre-set fro 60 millimetres (2.4 in) movement in the longitudinal direction and 10 millimetre (0.393700787401575 in) in the lateral direction and the centre line of top plate has been fixed relatively by 60 millimetres (2.4 in)/10 millimetre (0.393700787401575 in) with respect to centre line of bottom plate of the bearing which will permit the movements due to creep, shrinkage and elastic deformation. Their placement ensures that only longitudinal movement takes place without permitting any lateral moment. The pot bearings which support the girder are of 1050 tonnes capacity. Three sets of bearings were imported from Switzerland, while the balance bearings were made by M/s. BBR (India) Ltd.
Load test
Live Load test was carried out using hydraulic jacks (to apply point loads) with load applied in stages duly noting all parameters of design such as displacement in three directions (DX, DY and DZ) at all strategic locations of the arch and the girder. It was noted that the observed results showed a 95% correlation and was inferred that "the behaviour of the bowstring girder and various assumptions made during design were reasonably established."
Kovvur
Kovvuru is a small town, municipality and mandal in West Godavari district, in the state of Andhra Pradesh, India. It is situated adjacent to the west bank of the Godavari River.-Quick Facts:The name of Kovvuru was derived from Govu vooru...
-Rajahmundry
Rajahmundry
Rajahmundry is a city and municipal corporation of the Andhra Pradesh state in India. It is located east of the state capital, Hyderabad, on the banks of the River Godavari. Known as the Cultural Capital, Rajahmundry is noted for its intense Veda culture and intellect...
Bridge, is a new bridge built across the Godavari River
Godavari River
The Godavari is a river that runs from western to southern India and is considered to be one of the big river basins in India. With a length of 1465 km, it is the second longest river in India , that runs within the country and also the longest river in South India...
in Rajamundry in Andhra Pradesh
Andhra Pradesh
Andhra Pradesh , is one of the 28 states of India, situated on the southeastern coast of India. It is India's fourth largest state by area and fifth largest by population. Its capital and largest city by population is Hyderabad.The total GDP of Andhra Pradesh is $100 billion and is ranked third...
, India and is the third bridge in the series of bridges that exist on the river in the state. The other two bridges located upstream of the new bridge are the Old Godavari Bridge
Old Godavari Bridge
The Old Godavari Bridge or the Havelock Bridge was built in 1900 by Sir Arthur Cotton. Now decommissioned, it has 56 spans and is 2754 m long. It was constructed with stone masonry and steel girders, and was certainly a marvel of British engineering...
, a stone bridge known as the Havelock Bridge built by Sir Arthur Cotton in 1897 and parallel to it (since decommissioned), and the second railway bridge, a truss bridge, a functioning rail cum road bridge called the Godavari Bridge
Godavari Bridge
The Kovvur-Rajahmundry Bridge or simply, the Godavari Bridge is a Truss Bridge crossing the river Godavari in Rajahmundry, India. It is Asia's second longest road-cum-rail bridge crossing a water body, after Japan's Kansai International Airport Sky Gate Bridge.-Overview:Constructed over a quarter...
.
This prestressed concrete
Prestressed concrete
Prestressed concrete is a method for overcoming concrete's natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete...
(PSC) arch bridge, made of bow-string girder arches or tied-arches, was built between 1991 and 1997. It was commissioned for passenger traffic in March 1997 and became fully operational for running trains by the Indian Railways
Indian Railways
Indian Railways , abbreviated as IR , is a departmental undertaking of Government of India, which owns and operates most of India's rail transport. It is overseen by the Ministry of Railways of the Government of India....
from 2003. The bridge is said to be one of the longest span PSC arch bridges in Asia, and maybe in the world.
The single-track railway bridge is designed to run trains at a speed of 160 miles (257.5 km) per hour and is designed to withstand wind speed of 200 miles (321.9 km) per hour during cyclonic storms that are anticipated at this location. The bridge is considered an outstanding example of expertise of the Indian Railways
Indian Railways
Indian Railways , abbreviated as IR , is a departmental undertaking of Government of India, which owns and operates most of India's rail transport. It is overseen by the Ministry of Railways of the Government of India....
in this field.
The bridge, built by the Hindustan Construction Company
Hindustan Construction Company
Hindustan Construction Company is a construction company based in Mumbai, India, founded in 1926. HCC works in various sectors including transportation, power, marine, oil and gas pipeline construction, irrigation, utilities and urban infrastructure. HCC specializes in large-scale civil...
, for the Indian Railways, was designed by M/S Bureau BBR, Switzerland and checked by M/S Leonard Andrea and Partners, Germany. The Indian Railways who built this bridge have stated that "It is perhaps for the first time anywhere in the world that a bowstring arch girder using concrete has been constructed for such a long span of 97.55 metres (320 ft), and that too for the Railway loading."
Geography
The PCC arch bridge is built across the Godavari River (largest river in South IndiaSouth India
South India is the area encompassing India's states of Andhra Pradesh, Karnataka, Kerala and Tamil Nadu as well as the union territories of Lakshadweep and Pondicherry, occupying 19.31% of India's area...
at over 1000 kilometres (621.4 mi) length) as it enters into the deltaic reach before debouching into the sea 60 kilometres (37.3 mi) downstream of the bridge, the second largest river in India. At the location of the bridge, near Rajamundhry, the river flows with a width of about 3 kilometres (1.9 mi), split in two channels with an island formation in between. The maximum discharge observed in the river is reported to be around 3 million m3/s and the maximum velocity of water flow as 5 metres (16.4 ft) per second. The rail-cum-road bridge is on the railway line between Chennai
Chennai
Chennai , formerly known as Madras or Madarasapatinam , is the capital city of the Indian state of Tamil Nadu, located on the Coromandel Coast off the Bay of Bengal. Chennai is the fourth most populous metropolitan area and the sixth most populous city in India...
and Howrah and connects the East and West Godavari districts in the state of Andhra Pradesh. The bridge is located in a cyclonic area where the wind speed could touch 200 kilometres (124.3 mi) per hour. There are two other bridges across the same river on the upstream. In the immediate upstream of the new Godavari Arch Bridge, is the Havelock Bridge or the Old Godavari Bridge, which was built in 1897 by F. T. G. Walton under the guidance of Sir Arthur Cotton. It has 56 spans of 45.7 metres (149.9 ft) each and is 2950 metres (9,678.5 ft) long made of masonry piers and steel girders. When constructed it was considered a marvel of British engineering. However, it has been decommissioned after commissioning of the new arch bridge. The second bridge is a rail-cum road bridge, planned in 1964, known as the Godavari Bridge which was sanctioned to double the track between Kovvur
Kovvur
Kovvuru is a small town, municipality and mandal in West Godavari district, in the state of Andhra Pradesh, India. It is situated adjacent to the west bank of the Godavari River.-Quick Facts:The name of Kovvuru was derived from Govu vooru...
and Rajahmundry, upstream of the new bridge and is functional. The road deck was added on demand from the public. It has 27 spans of 91.4 metres (299.9 ft) and 7 spans of 45.72 metres (150 ft) including 6 spans of 45.72 metres (150 ft)located on the 6° curve near the Rajahmundry end to negotiate the built up area in that reach.
History
Initially when it was decided to build the third Godavari bridge to replace the Old Godavari Bridge, the planning was to provide for superstructure made of steel. As usage of concrete as construction material had become popular since its introduction in the 1930s, the issue of type of superstructure was re–examined by the Indian Railways. It was decided to examine the possibility of evolving a prestressed concrete (PSC) bridge with a 97.55 metres (320 ft) span. Firms were pre-qualified for the purpose with preferred options suggested for submission of offers, steel girder or concrete girder. Of the three firms who were shortlisted to submit offers, two firms opted for the concrete bridge option and one firm for the steel bridge option. On the basis of these offers, the railway authorities prepared the Terms of Reference prescribing the design criteria (as adopted in similar other PSC bridges), using of Design Codes, both International Codes (like BS: 5400) and UIC Codes. The three firms were asked to give their comments, and RDSO and Railway Board were also asked to indicate their views on the subject. Following this, the design criteria for the bridge was finalised. The offers received from the three firms were examined by Proof Consultants who recommended that the design offered by M/s. Hindustan Construction Company Ltd., (HCC), MumbaiMumbai
Mumbai , formerly known as Bombay in English, is the capital of the Indian state of Maharashtra. It is the most populous city in India, and the fourth most populous city in the world, with a total metropolitan area population of approximately 20.5 million...
be accepted. The firm had proposed the bowstring type concrete arch of span 92.552 metres (303.6 ft) with prestressed concrete box girder to act as tie. As this offer was found not only technically feasible but also financially acceptable, the order was placed on them to plan, design and build the bridge.
Features
The introduction of Reinforced Cement Concrete (RCC) as a construction technique for civil engineering structures, started in 1930s, has ushered many special types of bridges also, built in various parts of the world, and the third Godavari Arch Bridge is one such bridge in India built for the Indian Railways. The Godavari Arch Bridge is of the bow-string girder type bridge comprising prestressed RCC twin arches (constant width of 800 millimetres (31.5 in) with depth of arch varying from 1700 millimetres (66.9 in) at the springing to 1150 millimetres (45.3 in) at the crown) that are connected laterally with RCC struts (known as Viriendal struts) and PSC box girder. There are 28 identical spans of twin arches, spaced at 5600 millimetres (220.5 in) each of 97.552 metres (320.1 ft) width from centre to centre of the piers with a total length of 2745 millimetres (108.1 in). The effective span from centre to centre of the bearings is 94 metres (308.4 ft). The twin arches are of identical dimensions (with a parabolic profile) made in reinforced concrete (M45 grade). The PSC box girder is provided with footpath and hand rails and other related components.The final dimensions of the box girder are 95.462 metres (313.2 ft)×5200 millimetres (204.7 in) (bottom) with thickness of the top slab of 296 millimetres (11.7 in), the web of 300 millimetres (11.8 in) thickness and with the bottom slab thickness kept at 240 millimetres (9.4 in). A diaphragm stiffens the box girder at each Dina Hanger location. The substructure of the bridge consists of 28 piers. The bridge is located in two channels namely, the Kovvur channel and the Rajahmundry channel, and hence the bridge is also known as the Kovvur-Rajahmundry Bridge. The Rajahmundry channel has a deep rocky bed, and even the low water level is 18–20 m (59.1–65.6 ). However, comparatively the Kovur channel is shallow with a water depth of about 8–10 m (26.2–32.8 ) and river bed is made up of clayey deposits.
Design aspects
The superstructure of the bridge is of the Bow-string Girder type. Modified Broad Gauge (MBG) 1987 load conditions have been adopted for the design. The loading conditions are for axle load of 220.6 KN with EUDL of 80.9 KN. The projected speed for the trains is 160 km per hour. Under cyclonic conditions that may prevail in the area during cyclonic storms, the wind speed considered without live load is 200 kilometres (124.3 mi) per hour, and with live load the speed considered is 158 kilometres (98.2 mi) per hour. As the location of the bridge is in the Seismic Zone I, seismic load has not been accounted in the design. The arches are designed to share 80% of the Dead Load (DL) and Live Load (LL) transferred from the hangers and thus a plays a crucial role of relieving the flexural and shear stresses on the girder. Twelve (12) sinking supports are provided at each hanger location connecting with the girder.The box girder, which functions as the deck of the bridge and carries the live load, comprises end diaphragm (1000 millimetres (39.4 in) thick), which has inspection windows. The box girders are made of M42 grade concrete. Each girder is 95.552 metres (313.5 ft) long and was prestressed with 16 longitudinal cables, which in turn were prestressed to a force of 2950 kN each. (The BBRV system of prestressing was used for the permanent stressing of girder as well as temporary prestressing during construction under that bottom heading technique.) However, the bottom of the slab is provided with 24 lateral cables (two at each Dina Hanger location) which are also prestressed. In the stub part of the girder, six cables are provided laterally and duly prestressed. The flexing of the girders is directly linked to that of the arches, as the two are connected by hangers all along its length, at 12 locations. The design of the girder accounts for loading conditions of full span train load, half span train load, one third span train load and so forth with due accounting of temperature variation of ±10 °C (50 °F).
At each stage of casting of the girders (seven stages of casting were involved for each girder from girder stressing to removal of form work) forces generated in the arch section were studied and accounted, as required. The girder casting also ensured that no cracks appeared in the arches at any stage. Particular study was also done for the beginning part of the arch known as "starting stub", which has "distinct structural behaviour and has distinct function". Adopting a framework model, the stub was checked for cable force in temporary tendons as required for construction. The top deck slab was designed by analysis of "strip loads arising due to dispersion of axle loads through sleeper and ballast".
Each span of the bridge has 24 hangers, further divided under six types depending on their length. Each Dina Hangar is provided with 49 numbers of high tensile steel wires of 7 millimetre (0.275590551181102 in) diameter. The wires that run parallel to each other are encased in a high tensile polythene pipe, which is cement grouted. Based on detail analysis, the stress range for prestressing cables of the box girder was determined. The box girder was prestressed by "means of 16 longitudinal cables with a total force of 47177 KN and with lateral cables at each hanger location in the bottom slab."
Bearings
The bridge has been provided with pot bearings. On each pier, the girder is supported on four pot bearings of three types namely, the PNa type bearing (which facilitates free sliding in both directions) on one pier and PNe type (slides only in one direction) in the succeeding pier and PN type which is fixed type. The PNa and PNe type of bearings have been pre-set fro 60 millimetres (2.4 in) movement in the longitudinal direction and 10 millimetre (0.393700787401575 in) in the lateral direction and the centre line of top plate has been fixed relatively by 60 millimetres (2.4 in)/10 millimetre (0.393700787401575 in) with respect to centre line of bottom plate of the bearing which will permit the movements due to creep, shrinkage and elastic deformation. Their placement ensures that only longitudinal movement takes place without permitting any lateral moment. The pot bearings which support the girder are of 1050 tonnes capacity. Three sets of bearings were imported from Switzerland, while the balance bearings were made by M/s. BBR (India) Ltd.
Load test
Live Load test was carried out using hydraulic jacks (to apply point loads) with load applied in stages duly noting all parameters of design such as displacement in three directions (DX, DY and DZ) at all strategic locations of the arch and the girder. It was noted that the observed results showed a 95% correlation and was inferred that "the behaviour of the bowstring girder and various assumptions made during design were reasonably established."