BY PRAVIN KR. GAURAV

Traffic problem in Wajirabad road, Delhi

SIGNATURE BRIDGEIndia’s first “Signature Bridge ”being constructed across the Yamuna at Wazirabad promises to be a great attraction of Delhi. An ambitious project of the Delhi tourism, the cable-stayed bridge will link National Highway number one near existing T-point at Wazirabad on Western bank and Marginal Bund Road at Khajuri Khas on eastern bank of the river Yamuna, thus connecting North Delhi with East Delhi. With a length of about 575 meters and a height of 175 meters the proposed Signature Bridge would have a bow-shaped pylon in the middle. Two high towers will be there to provide double cable support in the inner periphery of the carriageway. Equipped with eight lanes, this engineering masterpiece will have 1.2 meter wide central verge, space for anchoring cables, maintenance walkway and crash barrier on either side of the central verge. The deck will be composite (steel and concrete) while pylon will be in steel.

Once operational the Signature Bridge will eventually improve access between North and west Delhi for the commuters, who have to pass through the narrow lane on the present bridge in Wazirabad, leading to heavy traffic jam in the peak hours. Also, to facilitate the movement of vehicular traffic new express lanes will be constructed to connect Ring Road with the bridge.

Signature bridge: An artistic view

Overview of projectPROJECT NAME : Signature Bridge(Yamuna bridge at Wazirabad)CLIENT : Delhi Tourism & Transportation Development Corporation Ltd.AGENCY : J.V. of M/s Gammon India & Construtora Cidade, TensacciaiDESIGN CONSULTANT : J.V. of M/s. Schlaich Bergermann Und Partner, Construma Consultancy pvt ltd.MumbaiPROOF CONDULTANT : J.V. of M/s. Systra, Virlogeux & Tandon Consultants .SUB-CONSULTANT : Ratan J.Batliboi Architects, Mumbai, Department ofEARTHQUAKE ANALYSIS :- IIT Roorkee & structural engg. Research center ,Chennai.LISENCE NO : CLA/c/13N/10PERIOD OF CONSTRUCTION: 20/3/2013 to 19/08/2016 (ESTIMATED)COST OF PROJECT : 1591 crore (revised) TOTAL LENGTH : 575m (8 lanes) 35.2m wide PYLON HEIGHT : 154 (5400 ton)  FOUNDATIONS : 6 open and 18 well foundations

Materials used in construction :-

1. Concrete ( M35 and M50 for kerb and deck M35 in well, M30 in pile.2. steel and concrete (Composite section )3. Steel bars (Fe 415 and Fe 500 reinforcement, TMT AND CRS bars)4. Coarse aggregate and fine aggregate

Shear ConnectorsShear connectors on the top flanges of steel girders provide the mean to achieve composite action between slab and girder, thus increasing both stiffness and strength. The shear flow between steel beam and reinforced concrete deck slab is a natural consequence of requirement for composite action.

Placement of deck slab over shear connector

Test on AggregatesSieve analysis of aggregatesSilt contentMoisture contentFlakiness and elongation testImpact valueAbrasion valueCrushing valueWater Ph / Cl / SO3 Cement physical TestSpecific density and gravityWater testingTMT bars

Silt content test of soilThere are two types of harmful substances preset in fine aggregates i.e. organic matter produced by decay of vegetable matter and/or clay and silt, which form coating thus preventing a good bond between cement and the aggregates. If present in large quantities, result in the increase water-cement ratio and finally affecting the strength of concrete. Field test is generally conducted in order to determine the volumetric percentage of silt in natural sand for percentage up to 8%, otherwise more detailed test as prescribed by standard code are required to be conducted.

Cube testThe test shall be conducted at recognized ages of the test specimens, the most usual being 7 days and 28 days. Where it may be necessary to obtain the strength tests at 1 day and 3 days can also be made. The ages shall be calculated from the time of the addition of water to the dry ingredients.

Size of Cubes- 150mm*150mm*150mm

These specimens are tested by compression testing machine after 7 days curing or 28 days curing. Load should be applied gradually at the rate of 140 kg/cm2 per minute till the Specimens fails. Load at the failure divided by area of specimen gives the compressive strength of concrete.

  

Aggregate impact valueThis test is done to determine the aggregate impact value of coarse aggregates. The apparatus used for determining aggregate impact value of coarse aggregates is Impact testing machine A cylindrical metal measure of 75mm dia. and 50mm depth, A tamping rod of 10mm circular cross section and 230mm length, rounded at one end and Oven.

PILE FOUNDATION• Our Structure is rested on a weak soil formation which can’t resist the

loads coming from our proposed building, so we have to choose pile foundation.

Pile cap

PilesWeak soil

Bearing stratum

Pill ing Steps Sur vey : T he su rve yor set ou t th e c en ter o f th e b ore d pile loc ati on.  Util ity div ers ion : A c irc ula r p it o f d iam ete r 17 00 mm a nd dep th 1 50 0 m m sh all b e m an ua lly ex cav ate d a t th e l oca tion to en sur e t hat the uti litie s a re pre sen t.

Che ck s fo r P ile ve rtica lly an d p os itio n: D urin g t he pro ce ss o f b orin g f oll owi ng c he cks sh ou ld be m ad e: Che ck the ve rti cal ity o f th e c as ing du ring in s ta llat ion by plu mb ing fro m two pe rpe ndi cul ar dire ctio ns . Che ck of the ec ce ntric ity of the bo reh ole aft er i ns t all atio n o f ca s in g. If t he ecc ent ric i ty i s m or e th an 50m m th en rein s ta llat ion is do ne. The ve rtic ali ty of t he c as ing is ch eck ed con tin uou s l y u ntil the toe is re ach ed and is ke pt with in a to lera nc e o f 5 0mm . Var iati on in d im en s ion is lim ite d t o + 50m m an d - 10 mm .  Var iati on of l ev el a t th e to p s ho uld no t be be yo nd + 2 5m m.  Bor ing of soi l-B orin g is ca rrie d o ut wit h th e h elp of a r ig u p to th e re qu ire d d epth . T he ver tic alit y of the ho le to be bore d i s k ept on m onit ore d a nd lat er c hec ke d b efo re the low erin g o f th e rein forc em en t ca ge . Ins tall atio n o f t em pora ry cas ing to s t abil ize the up pe r b ore, a t em por ary s t eel cas ing of le ngt h 2. 5- 3 m is i ns tall ed: A 1 000 mm d iam et er h ole is dril led us ing hy dra ulic b orin g m ac hin e u p t o a dep th of 3 -4m .  The ca s in g s ho uld the n b e l owe re d in the ho le with th e h elp of a c ran e.  The ca s in g i s t hen dri ven in to the gr oun d w ith the he lp of a rot ato ry m a chi ne u nti l ab ou t 3 00m m is l eft abo ve th e gr oun d. The ri g is the n u se d to p rog ress th e e xca va tio n to the bo tto m of t he c as ing pip e and the n s uit abl e p oly me r sy s te m is add ed bef ore fur the r e xca vat ion .  Ben ton ite sh ou ld b e a dde d c on tin uou s ly du ring ex ca va tion . An d t he de pth is m ea su red wi th t he h elp of the s oun din g ta pe .  

Cleaning of base:  Boring is stopped when the toe of the pile level is reached. The borehole is cleaned carefully and the soil is removed. The depth is checked before the lowering of the cage.  Fabrication and installation of reinforcement cage:  Cutting and bending of bars shall be carried out with approved schedule in fabrication yard or on the site. Tie wires shall be used for binding the bars. Circular concrete spacers shall be provided of the same grade of the pile. Vertical distance between each layer of spacers shall be 4m. The reinforcement cages shall be lowered in the borehole using steel slings and shackles. Cages shall be spliced on the fabrication bed and lowered in the trench.  Concrete with slump in the range 175+25mm shall be supplied from batching plant. All concrete delivered shall be visually inspected and checked against delivery note before being tested and used. Before a pouring is started two delivery trucks should be available at site.  Concrete shall be placed using pipes.  Pipes are joined towards into the hole. The end of the pipe should not be more than 300 mm above the bottom of the pile to ensure that free fall of concrete shall not be more than 1.5m.  The concrete shall be discharged from the delivery truck to a hopper connected to the pipes. As the level of the concrete in the borehole rises, the s shall be withdrawn accordingly to aid the flow of concrete. Section of the pipe shall be dismantled from the top as the pipe is withdrawn.  During concreting, the level of concrete inside the borehole shall be monitored either with a weighted tape or chain. Encasing shall be withdrawn after initial setting of concrete

Casing in pile20mm dia bars are used.pitch of helical striupps are 200mm4 master ring, 3 pair square ring, 16 longitudional bardia of helical bar 10mmlength of cage – 8.8mmdia of cage – 1050mmSize of helical bar – 10mmlap length – 72* dia of bar

Pile load testDone after 28 days of construction.Acceptable limit of penetration should not be less than12mm.There should be a overbound of 1 or 2 mm.Loads applied as per loading of girder.

Reinforcement in pile cap

Batching plantSignature bridge batching plant has a capacity to deliver a 60 cubic

meter per hour. The batching mixer mixes the following cement, sand, aggregate , admixture, fly ash and water.

Casting YardIn casting Yard, deck slab and bridge kerb, welding works were made.

Deck Slabdeck slab used in site comprised of M50 grade concrete. 32mm steel bars of Fe500.

Kerbskerb is a stone or concrete forming an edge between a pavement and a roadway, so that the pavement is somewhat above the level of road.

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