CASE STUDY ON CONSTRUCTION OF SUPER STRUCTURE BY CAST IN PLACE METHOD

1. CASE STUDY ON CONSTRUCTION OF
SUPER STRUCTURE BY CAST IN PLACE
METHOD
PRESENTED BY :
KHAUSHAL TADAS

2. Cast in Place
INTRODUCTION:-
Cast-in-place concrete, also known as poured-in-place, is a concreting technique which is
undertaken in situ or in the concrete component’s finished position. Cast-in-place
concrete is the preferred choice for concrete slabs and foundations, as well
as components such as beams, columns, walls, roof’s, and so on.
 Allows concrete to be formed to site conditions
 Used on most construction sites for structural members
 Concrete placed in forms to cure
 Forms removed after enough strength in concrete to support self and additional
construction loads

3. ADVANTAGES OF CAST-IN-PLACE METHOD & PRECAST
CONCRETE
CAST-IN-PLACE PRECAST CONCRETE
 Limitless flexibility of shape and size.  Entire building can be precast-walls,
floors, beams etc.
 Wide variety of surface and textures can
be achieved.
 More durable than real masonry.
 Homogeneous connections.  Optimum use of materials.

4. DISADVANTAGES OF CAST-IN-PLACE METHOD &
PRECAST CONCRETE
CAST-IN-PLACE PRECAST CONCRETE
 Needs high labor and plant on site.  Very heavy members.
 Formwork is time consuming.  Connections may be difficult.
 Quality control is difficult.  Somewhat limited building design.

5. CASE STUDY :- IOWA RIVER BRIDGE

6. INTRODUCTION:-
 The bridge was constructed using the launching method due to a number of very
stringent environmental restrictions near the project.
 These environmental issues included endangered mussel species residing in the
Iowa, endangered plant species near the site and Native American artifacts near
the site.
 In addition, a bald eagle roosting area was identified near the site. An extensive
environmental monitoring program was established and maintained during
construction.

7. BRIDGE STRUCTURAL DESCRIPTION
 The bridge consists of two parallel deck superstructures, each with five equal
spans of 92 m (302’). A 19 m (62’) prestressed concrete jump span is provided
on each end of the steel unit.
 The I-girders were fabricated from ASTM A709 Grade 345 weathering steel;
they are 3450 mm (11’) deep and spaced at 3600 mm (12’) centers.
 To make the I-girder superstructure act as much like a torsionally rigid box
girder as possible during launching, a stiff system of diaphragms and lateral
bracing was used.
 A diaphragm spacing of 7,000 mm (23’) was used for spans two through five,
but was reduced to 3,500 mm (11’6”) in the leading span that would be
cantilevered during launching.

8. BRIDGE LAUNCHING SYSTEM
 The bridge superstructure was completely erected on steel falsework and
custom-made 18” diameter rollers behind the east abutment.
 A 146’ long, tapered steel launching nose was erected at the leading end of
the girders and used to reduce the cantilever deflection during each launching
operation.
 After each span was launched forward, additional steel girder sections,
including diaphragms and bracing, were pushed forward to land on the
subsequent pier.
 The process was completed five times for each steel superstructure. After the
complete launching of the eastbound girders, the falsework was removed and
reinstalled to perform an identical launching of the westbound superstructure.

9. PROJECT PHOTOS

10. CASE STUDY:- THE STONEY TRAIL
BRIDGE

11. INTRODUCTION
 The Stoney Trail Bridge is a horizontally curved, segmentally constructed
bridge and was the second incrementally launched reinforced concrete bridge
to be built in North America (first in Canada).
 Each of the concrete segments was built on one bank and then jacked
horizontally into its final position atop 30 m high ‘Y’ shaped concrete piers.
 This structure is the featured element of a $48M (Canada) project forming the
first leg of a long awaited northwest perimeter transportation corridor for the
city of Calgary.
 The incremental launching technique was particularly well suited for this
project because of the $1.5M (Canada) cost savings that this method offered,
and also because of the sensitive nature of the surrounding environment: the
south bank contains one of the few stands of Douglas Fir trees in this area.

12. BRIDGE DESCRIPTION
 The bridge is a 476 m (1562 ft) x 21 m (68 ft), 5-span structure with a main
span of 102 m (335 ft), 40 m (131 ft) above the Bow river valley. The
superstructure consists of a 4.5 m (15 ft) deep girder elements.
 It consists of cast-inplace concrete abutments, piers and superstructures.
 The superstructure section is a post-tensioned, double-celled monolithic
concrete box structure and was cast in two stages: soffit and webs cast
together, followed by the deck in two segmental casting beds.
 The box girder and deck was assembled in segments (total of 19 segments) on
the north bank, post-tensioned with steel reinforcing cables, and then pushed
from the north abutment to the south.
 Each completed segment (1200 tons) is 25.5 m (84 ft) long with the exception
of end segments which are 22 m (72 ft) long

13. BRIDGE CONSTRUCTION AND LAUNCHING
 The bridge construction involved curved, post-tensioned segmental concrete
placed with hydraulic jacks for both vertical lifting and horizontal sliding.
 The bridge superstructure was pushed and pulled with hydraulic jacks over a
system of temporary sliding bearings and lateral guides that were mounted on
permanent and temporary piers.
 During the launching, external post-tensioning was performed inside each cell
to provide the structural support.
 The precise/prestressed construction methodology reduced the amount of
equipment and limited work crew contact with environmentally sensitive sites.
Special attention was given to minimize the amount of runoff discharge
directly into the river.

14. PROJECT PHOTOS

15. THANK YOU