In bridge widening projects, the method of stitching is normally employed for connecting existing deck to the new deck. What are the problems associated with this method in terms of shrinkage of concrete?

In bridge widening projects, the method of stitching is normally employed for connecting existing deck to the new deck. What are the problems associated with this method in terms of shrinkage of concrete?

In the method of stitching, it is a normal practice to construct the widening part of the bridge at first and let it stay undisturbed for several months. After that, concreting will then be carried out for the stitch between the existing deck and the new deck. In this way, the dead load of the widened part of bridge is supported by itself and loads arising from the newly constructed deck will not be transferred to the existing deck which is not designed to take up these extra loads.

One of the main concerns is the effect of stress induced by shrinkage of newly widened part of the bridge on the existing bridge. To address this problem, the widened part of the bridge is constructed a period of time (say 6-9 months) prior to stitching to the existing bridge so that shrinkage of the new bridge will take place within this period and the effect of shrinkage stress exerted on the new bridge is minimized.

Traffic vibration on the existing bridge causes adverse effect to the freshly placed stitches. To solve this problem, rapid hardening cement is used for the stitching concrete so as to shorten the time of setting of concrete. Moreover, the stitching work is designed to be carried out at nights of least traffic (Saturday night) and the existing bridge may even be closed for several hours (e.g. 6 hours) to let the stitching works to left undisturbed.

Sometimes, longitudinal joints are used in connecting new bridge segments to existing bridges. The main problem associated with this design is the safety concern of vehicles. The change of frictional coefficients of bridge deck and longitudinal joints when vehicles change traffic lanes is very dangerous to the vehicles. Moreover, maintenance of longitudinal joints in bridges is quite difficult.   

Weight of steel bars per meter – Weight of steel bars formula

Diameter of bars in millimeter	Weight of bars in kilogram
6 mm	0.22 kg/meter
10 mm	0.62 kg/meter
12 mm	0.89 kg/meter
16 mm	1.58 kg/meter
20 mm	2.469 kg/meter
25 mm	3.858 kg/meter

Weight of steel bars formula

To calculate weight of steel bars, there is a formula used to calculate weight.

W=(D^2 x L)/162

what is Rough cost estimate

what is Rough cost estimate

Rough cost estimate is also called approximate estimate. Because in approximate estimate we can find out the estimation of building an approximatly.This is an inexact estimate to find out a rough cost in a short time which enables the authority concerned to consider the financial aspect of the scheme, for according sanction to the same. Such an estimate is framed after knowing the rate of similar works and from practical knowledge in various ways for various types of works such as.

Approximate estimate can find out with the help of Plinth area or square-meter , Approximate quantities with bill,Cubic rate or cubic meter and The cost of materials and labor. so we can find out the approximate or rough cost estimate with these method which i have discussed. so the approximate estimate is generally used for rough cost estimate, which are just used for simple project. but remember this estimate is not accurate in construction works, because this is just approximate quantity.

Types of Estimate

Types of Estimate

• Original Estimate
• Repair Estimate

Types of Original Estimate

1. Rough Cost Estimate
2. Detailed Estimate

Types Of Rough Cost Estimate

• Per Unit Number
• Plinth Area Basis
• Cube Rate Estimate 
• Per Unit Length of Wall
• Per Unit Length of Road & Heighway
• Per Unit Length of Irrigation Channel
• Per Unit Length of Railway Track
• Per Litre For Over Head Water Tanks

1. Detailed Estimate

Detailed Estimate take every quantity of every item and multiply with unit of rate..
\
for example…

• excavation.. 
• Brick Masonary.. 
• R.c.c. 
• Plaster
• Steel 
• Flooring
• Tile and fishing work

First we take measurement and them prepared abstract of Cost.

   2.  Types Of Repair Estimate

• Annual Repair Estimate
• Quadrennial Repair Estimate
• Special Repair Estimate

What is Quantity Surveying/ Estimation

Quantity Surveying/ Estimating

An art to collect data about material and cost required for a project is called
QUANTITY SURVEYING/ESTIMATING.
The Process of cost estimating is working out how much a building or other
construction will cost to make. The cost are usually divided into material and labour
cost..

TENDERING is the process of making a priced offer to construct the building. This is a
legally enforcable offer made within the conditions of the tender documention.
Necessary data for preparing an estimate of project are

1. Drawings
2. Specifications 
3. Rates.

Types of Estimate
A. Original Estimate
B. Repair Estimate

RATE ANALYSIS sandwich panel Sheet 50mm mm thick ( Pre painted )

RATE ANALYSIS
	Job Description
Providing , installation of M.S sandwich panel Sheet 50mm mm thick ( Pre painted ) over M.S frame structure  using hex washer head self tapping & drilling screws and over laping G.I Sheet 24-SWG at corners painted with matching colour  i/c carrage of material from lahore to Gojra at site of work through Cantainer/troller , charges of uplifting through crane at 40' height for installation, cost of all other  materials ,  labour  etc complete in all respects as per drawing and design  as approved and advised by the Consultant / Engineer Incharge.
(1st BI-ANNUAL-2017 , 01.01.2017 TO 30.06.2017)
Unit:	P. Sft				Take for analysis= 37.5' x 45'=1687.5 Sft
S. No.	Description					Unit	Quantity	Rate	Amount
A	Materials
1	M.S Sandwich panel sheet full width 38ft.
	Top                    38' x 37.5'		=	1425	Sft
	Front                    37.5' x 2.66'		=	99.75	Sft
	Back                    37.5' x 5.66'		=	212.25	Sft
	Add wastage 5 %			86.85	Sft
		Total	=	1823.85	Sft	Sft	1,823.85	580.00	1,057,833
	G.I Sheet 24 SWG
	Front                    37.5' x 1'		=	37.5	Sft
	Back                    37.5' x 1'		=	37.5	Sft
	Add wastage 5 %			3.75	Sft
		Total	=	78.75	Sft
	78.75 Sft @ 1.156 Lbs/Sft		=	41.33	Kgs	Kg	41.33	100.00	4,133
2	hex washer head self tapping & drilling screws
	Top and sides @ 3' c/c			247	Nos
	Add wastage 10 %			25.00	Nos
		Total	=	272.00	Nos	Nos	272.00	35.00	9,520
3	Steel cutting disc					Each	5.00	480.00	2,400
4	Electricity					Unit	75.00	20.00	1,500
	Total Amount ( A ):								1,075,386
B	Carriage and hire charges
2	38' Length roof sheet panel on troller container i/c loading & Unloading					Each	33%	30,000.00	10,000
4	Drill machine for 3 days @ 300 / day					Day	3.00	300	900
6	Crane for uplifting the full length sheet panels and placing them at proper place upto 40' height.					Day	1.00	30000	30,000
	Total Amount ( B ):								40,900
C	Labour
(a)	Labour required  Fixing M.S Sandwich Panel Sheet.
1	Technician
	1 Nos for 3 days					Days	3.00	2,800	8,400
2	Skilled Cooly ( LB-024)
	4 Nos for 3 days					Days	12.00	608	7,296
	Add sundries 10%								1,569.6
	Total Amount ( C ):								17,266
	Total Amount (A+B+ C ):								1,133,552
	Contractor profit , taxes , site expenses and  over head 20%								226,710.3
	Grand Total Amount:								1,360,262
	Rate Per Sft   =	1360262/1687.5							806.08
							Say Rs	806	P/Sft