Prestressed Concrete Structures Interview Questions and Answers for Experienced people on “Case Study on Repairs and Rehabilitation of Structures”.
1. The super structure in Swanley bridges in U.K is made up of a continuous slab supported on ____________
a) Longitudinal piers
b) Transverse piers
c) Inclined piers
d) Curved piers
Answer: c
Clarification: These highway bridges from part of M25 and M20 mortar way intersection and the super structure is made up of continuous slab supported on the inclined piers and shortly after the bridge was opened for traffic, cracks were observed on the soffit of deck slab at the end sections.
2. A design review indicated that the reinforcements at the cracked locations were ____________
a) Adequate
b) Inadequate
c) Collapse
d) Deform
Answer: b
Clarification: A design review indicated that the reinforcements at the cracked locations were inadequate hence the missing reinforcement was introduced in the form of bonded steel plates 6mm thick, 250mm wide and 3 to 6m long plates bonded in three layers in each strip and each strip of reinforcement was 12m long and 15 strips were distributed over the entire width of the bridge.
3. The concrete deck slab and girders of Gizener bridge, Switzerland was built in the year?
a) 1911
b) 1920
c) 1915
d) 1900
Answer: a
Clarification: The concrete deck slab and girders of this bridge built in the year 1911 and located in Switzerland has to be strengthened to withstand planned future loading and the damaged parts of the bridge deck slab was repaired using epoxy resin mortar.
4. The super structure of Obra singrauli bridge, located on eastern railway in Indian is of span ____________
a) 14.3
b) 18.3m
c) 16.3m
d) 12.3m
Answer: b
Clarification: The super structure of Obra singrauli bridge located on eastern railway in India comprises of 4 numbers of 18.3m spans and one number of 24.4m span and decking is made up of two prestressed concrete girders stressed with Freyssinet system of post tensioning and after 15 years of service the prestressed girders developed large number of cracks at the junction of girder and deck slab on both internal and external faces.
5. The deck in Quinton bridge in U.K is made of ____________
a) Voided slabs
b) Concrete slabs
c) Prestressed slabs
d) Elongated slabs
Answer: a
Clarification: The deck is made up of voided slabs 90-105cm thick and routine inspection indicated cracks in the soffit of end and central sections and review of design calculations indicated deficient tensile reinforcements at certain locations of the deck slabs, the following two rehabilitation methods were examined: installation of prestressing elements and external reinforcement with bonded on steel plates.
6. The super structure of Katepura bridge in Maharashtra state comprises of ____________
a) Cantilever beam
b) SSB
c) Point
d) Simple beam
Answer: b
Clarification: The super structure of Katepura bridge in Maharashtra state comprises of simply supported concrete girders with reinforced concrete structures deck slab and the bridge has 4 spans of 37.8m and the girders were cast in place over temporary staging and side shifted to position after necessary post tensioning of the girders.
7. The restoration of the end block of the girder can be done completely dismantling the ____________
a) Concrete
b) Cement
c) Water
d) Aggregates
Answer: a
Clarification: The restoration of the end block of the girder was done by completely dismantling the concrete in the end block after distressing of the cables and new reinforcement was welded with the existing reinforcement of the girder and new concrete with vertical joint was provided with extra care.
8. The Chambal bridge is on a state highway connecting which states?
a) Karnataka and Kerala
b) Delhi and Hyderabad
c) Uttar Pradesh and Madhya Pradesh
d) West Bengal and Assam
Answer: c
Clarification: The Chambal bridge is on a state highway connecting Uttarpradesh and Madhya Pradesh, built across river Chambal near etawah in Uttarpradesh and the bridge is 592m long with a bridge deck comprising of single cell reinforced concrete box girders of 11.1m length projecting on either side of the pier and the suspended span comprises of two prestressed concrete girders with reinforced concrete deck slab of span 40.6m.
9. The suspended span comprises of how many prestressed concrete girders?
a) 4
b) 2
c) 6
d) 1
Answer: b
Clarification: The suspended span comprises of two prestressed concrete girders with reinforced concrete deck slab of span 40.6m and cast steel rocker and roller bearings have been provided at articulations for supporting the suspended span and soon after the bridge was constructed and opened to traffic in1975, it developed distress due to improper placing of roller bearings.
10. The investigations revealed that the bearings were not at ____________
a) 60 degrees
b) 30 degrees
c) 90 degrees
d) 20 degrees
Answer: a
Clarification: The investigations revealed that the bearings were not at right angles to the axis of the bridge and the level of downstream side bearing was lower by 35mm as compared to the elevation of upstream bearing and hence due to transfer inclination of the bearings towards downstream, the span had a tendency to move in the transverse direction.