708 - Prestressed Concrete - Revision history

JohnsonN23: /* Delivery of Structural Precast Concrete Elements */

2018-01-17T13:38:02Z

Delivery of Structural Precast Concrete Elements

JohnsonN23: update 1/17/2018

2018-01-17T13:35:22Z

update 1/17/2018

Show changes

JohnsonN23: JohnsonN23 moved page 708 - Precast Concrete Beams (Prestressed) to 708 - Prestressed Concrete

2018-01-17T12:34:57Z

JohnsonN23 moved page 708 - Precast Concrete Beams (Prestressed) to 708 - Prestressed Concrete

Greenes2 at 13:51, 21 May 2014

2014-05-21T13:51:06Z

Greenes2: /* DELIVERY OF STRUCTURAL PRECAST ELEMENTS */

2014-05-15T13:43:41Z

DELIVERY OF STRUCTURAL PRECAST ELEMENTS

Greenes2: /* FABRICATION OF PRESTRESSED CONCRETE */

2014-05-15T13:42:56Z

FABRICATION OF PRESTRESSED CONCRETE

Greenes2: /* PRESTRESSED CONCRETE ELEMENTS */

2014-05-15T13:41:57Z

PRESTRESSED CONCRETE ELEMENTS

Greenes2: /* Box Beams */

2014-05-15T13:40:59Z

Box Beams

Greenes2: /* I-Beam and 1800 Beams */

2014-05-15T13:40:37Z

I-Beam and 1800 Beams

Greenes2: /* Construction Inspection */

2014-05-15T13:40:18Z

Construction Inspection

@@ Line 154: / Line 154: @@
 The Structural Fabrication Unit will send a fabrication inspection memorandum via ProjectWise link to the project office at the end of each project. This memorandum is not the basis of acceptance, but rather a brief summary of the fabrication inspection for the project. The project office should use it as a reference when requesting fabrication information from the Structural Fabrication Unit. All fabrication records are stored in the project folder in ProjectWise.  See Figure 708.11 for a sample inspection memorandum.
-[[File:Fig_708-11.png|600px|thumbnail|center|Figure 708-11 Crack comparator for measuring crack width]]
+[[File:Sample Structural Precast Concrete Memo.jpg|600px|thumbnail|center|Figure 708-11 Sample Structural Precast Concrete Memo]]
 {{top}}
 ==[[#Structural Precast Concrete Field Storage|Structural Precast Concrete Field Storage]]==

← Older revision		Revision as of 13:51, 21 May 2014
Line 6:		Line 6:
	<center>[http://mdotcf.state.mi.us/public/specbook/files/2012/708%20Prest%20Concrete%20Beams.pdf 2012 STANDARD SPECIFICATIONS FOR CONSTRUCTION - SECTION 708]</center>		<center>[http://mdotcf.state.mi.us/public/specbook/files/2012/708%20Prest%20Concrete%20Beams.pdf 2012 STANDARD SPECIFICATIONS FOR CONSTRUCTION - SECTION 708]</center>

−	~~<span style="color: red"> -'''This Section Currently Undergoing Substantial Revision-''' </span>~~

	==[[#GENERAL\|GENERAL]]==		==[[#GENERAL\|GENERAL]]==

@@ Line 180: / Line 180: @@
 ==[[#CONSTRUCTION|CONSTRUCTION]]==
-===[[#DELIVERY OF STRUCTURAL PRECAST ELEMENTS|DELIVERY OF STRUCTURAL PRECAST ELEMENTS]]===
+===[[#Delivery of Structural Precast Elements|Delivery of Structural Precast Elements]]===
 When prestressed or non-prestressed structural precast structural concrete elements arrive on the job site, inspect them before they are unloaded.  Check ends of each beam for a stamp or tag stating “Approved for Use.”  If the beams are delivered to the project site without an approval stamp or tag, reject the beams.  If the beams are approved for use, a memorandum will be sent to the TSC from Bridge Field Services stating the approval of each beam and verification of all material certifications and test results. According to [http://www.michigan.gov/documents/mdot/MDOT_MQAP_Manual_5_Section_D_307110_7.pdf Section 4.04 of the MDOT Materials Quality Assurance Procedures Manual] prestressed concrete fabrication has been approved for use by MDOT when the following two part process is met:

@@ Line 106: / Line 106: @@
 {{top}}
-===[[#FABRICATION OF PRESTRESSED CONCRETE|FABRICATION OF PRESTRESSED CONCRETE]]===
+===[[#Fabrication of Prestressed Concrete|Fabrication of Prestressed Concrete]]===
 {{top}}

@@ Line 46: / Line 46: @@
 {{top}}
-===[[#PRESTRESSED CONCRETE ELEMENTS|PRESTRESSED CONCRETE ELEMENTS]]===
+===[[#Prestressed Concrete Elements|Prestressed Concrete Elements]]===
 Prestressing, refers to the process of pulling steel tendons in the beam into tension before the concrete is placed in the forms.  After the concrete has hardened, the stressed tendons are released and transmit a compressive stress to the concrete.  This offsets tension forces on the concrete and increases the load-carrying capacity of the beam.  The result is similar to pressing on the ends of a set of books in order to pick up the whole set of books at once.

← Older revision	Revision as of 12:34, 17 January 2018
(No difference)

← Older revision		Revision as of 13:40, 15 May 2014
Line 169:		Line 169:


−
−	~~{{top}}~~
−
−	~~===[[#Box Beams\|Box Beams]]===~~
−
−	To ensure that box beams will fit properly on the substructure units, the beam widths should be checked. Beam bearing pads must be shimmed in an approved manner during erection to provide full bearing contact with the bottoms of the beams. This needs to be checked on every box beam. Note in the daily report when the beam erection has been completed.
−
−	The beams should be set with spaces between the beams as specified on the plans or shop drawings and with the seal washers placed in the duct holes. The space between the beams should be completely filled, full depth, with R-2 mortar and cured for at least 48 hours. The deck width should be measured by the Contractor as soon as the beams are set to assure that post tensioning rods or tendons will be fabricated to the proper length.
−
−	All hardware dimensions must be as shown on the plans or shop drawings. Tendons or rods should be tensioned with calibrated jacks according to a Contractor-supplied calibration chart showing the corresponding jack pressures and rod elongations necessary to gradually build up to the required stressing force. After the tensioning is complete, the tendon or rod holes will be grouted as described in the standard specifications.
−
−	~~'''Do not stand behind the jacking machine or rod holes during jacking procedures. If a tendon or rod snaps, it will cause serious injury.'''~~

	{{top}}		{{top}}