Challenge

Challenge 7

KKumar Souryaman4 Aug 2022

Bridges DESIGN

Challenge 7

Calculate the moment for design of pier cap considering reactions @ 250mm from tip of cantilever: D.L. (100kN), SIDL (80kN), & LL (120kN). Total length of the cantilever from the pier face is 4.5m. Consider an impact of 1.3 for live load.

SOLUTION- SLS load combination = DL+1.2*SIDL+1.1*LL*l

=(100+1.2*80+1.1*120*1.3) kN =367.6 KN

MOMENT @ PIER FACE =( 367.6*4.5)KN-m = 1654.2 KN-m

2.Differentiate between RCC and PSC pier caps in all aspects

“Pier caps transfer the loads from the superstructure to the piers. They hold the bridge girders on bearing pads and disperse the loads from the bearings to the piers. Bridges with piers will all have pier caps to transfer the load from the superstructure.

write the difference between rcc and psc pier caps.

rcc pier caps

STRENGTH

strength has very good in tension as well as compression

DURBLITY

RCC structure are durable it designed and laid properly they can last up to 100 years

MOULDABLITY

RCC section can be given any shape easily by properly designing the formwork thus it is more suitable of architectural reqirement .

DUCTILITY

The steel reinforcement imparts ductility of the rcc structure

ECONOMY

RCC is cheaper as campared to steel and prestress concrete there is an overall economy by using rcc because it maintenance cost is low.

TRANSPORTATION

The raw materials which are required for rcc ie cement sand aggregate water and steel are easily availble and can be transported easily nowday ready mix concrete is used for faster and better construction,

FIRE RESISTANCE

RCC structure are more fire resistant than other commonly used construction materials like steel and wood

PERMEABILITY

RCC is almost impermeable to moisture ,

psc pier caps.

Prestressed concrete sections are thinner and lighter than RCC sections, since high strength concrete and steel are used prestressed concrete.
In prestressed concrete, whole concrete area is effective in resisting loads, unlike RCC where concrete below the neutral axis is neglected.
Thinner sections in prestressed concrete results in less self weight and hence overall economy.
Prestressed concrete members show less deflection.

3.Provide the codal provisions for design crack width depending on the various exposure conditions.

RELEVANT CODAL PROVISION

* TABLE 11 CLAUSE 10.2.2 OF IRS CBC STRESS LIMITATIONS FOR THE SERVICELIBLITY LIMIT STATE.

MATERIAL TYPE OF STRESS UNDER DESIGN LOADING TYPE OF CONSTRUCTION

R.C.C PSC

CONCRETE TRIANGULAR OR MEAR TRIANGULAR COMPRESSIVE STRESS 0.50FCK 0.40FCK

UNIFORM OR NEAR UNIFORM COMPRESSIVE STRESS (E.G Y

DUE TO AXIAL LOADING 0.38FCK 0.30FCK

REINFORCEMENT COMPRESSION TENSION 0.75FY NA

PRE-STRESSING TENDONS TENSION NA DEEMED TO SATISFIED BY

16.8.1

TABLE 10 ( CLAUSE 10.2.1) OF IRS CBC DESIGN CRACK WIDTH THE VARIOUS EXPOSURE CONDITIONS

EXPOSURE CONDITION DESIGN CRACK WIDTH IN MM

MODERATE _ 0.20
SERVERE _ 0.10
EXTREME _ 0.10

4.At what conditions, the cantilever pier cap is preferred and state the limitations of the same.

SOLUTION- this piercap special is the incidence of two types of girders-concrete I-Sections and a Single Celled Box girders. The metro line, in this plan, meets a depot line that advances to the metro depot. The main track line deviates into the metro depot in two separate tracks. The main line of the metro is designed using the box girders a depot line is designed using I-section girders. Both these girder systems have 2 Metro rail tracks each.

Both sides of the pier have a span of about 25m and 28 m on either sides. The depth of the cap at pier face, 1.5m in total,

and where more population area and we prefferd more space it making centreline of road between .

on cantilever pier place two box girder seated one on the right side and one the left side and they provied clearly centre line of alignment .

limitation

appearance

vertical clearnace.etc

Challenge 7

Ship work like this
in your own course.

Talk to a career counsellor

Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.