Create a differential temperature profile to ensure the beam can accommodate temperature-related effects over time.
Transcript
00:03
In Structural Bridge Design, once you design a beam, there are several types of loads to consider.
00:10
One of these is environmental loads, such as a differential temperature profile.
00:16
This type of load accounts for the temperature variations within the structure, which can cause expansion and contraction of materials.
00:24
In this scenario, a composite, pretensioned, precast beam
00:29
and a 21-meter-long, 2-meter-wide concrete slab are designed, with dead loads, construction loads,
00:36
and live loads already applied.
00:40
The next step is to create a differential temperature profile, including the associated shrinkage and shear parameters.
00:47
When creating the profile, keep the following specifications in mind
00:52
to ensure that the beam design can accommodate temperature-related effects over time:
00:57
While primary stresses need to be calculated, there are no secondary effects due to temporary shrinkage, as the beam is statically determined.
01:06
The temperature profile applied should be based on the expected differential temperatures across the section
01:12
and should consider a surface finish of 100 millimeters thick.
01:16
The concrete is expected to have a total shrinkage strain of -0.00025,
01:23
with 20% of this shrinkage occurring before the in-situ slab is cast in place.
01:28
There is a differential shrinkage strain of -0.0001, and the concrete is expected to exhibit creep behavior with a creep coefficient of 1.5.
01:41
With the beam design open and Design Beam activated in the Navigation Pane, in the navigation toolbar, click Analyse.
01:50
In the Pre-tensioned Beam Analysis form, expand the Analyse for drop-down and select Differential temperature primary stress.
01:59
This opens the Differential Temperature Analysis form, along with a preview in an additional graphics window.
02:07
In this form, adjust the Type to Non Linear, change the Type of Deck to Type 3b: concrete beams, and set the Surfacing thickness to 0.1.
02:18
Then, click OK to accept the differential temperature profile.
02:22
Back in the Pre-tensioned Beam Analysis form, expand the Set parameters for drop-down and select Time dependent effect calculations.
02:32
In the form that opens, enable shrinkage strain and set it to .000251504.
02:41
Then, enable and set Long term losses to 20%, differential shrinkage to .0001, and creep coefficient to 1.5.
02:52
Click OK to save these parameters.
02:55
Back in the Pre-tensioned Beam Analysis form, set the Exposure to XD1, and then click OK.
03:04
Creating a differential temperature profile with associated shrinkage and shear parameters
03:09
accounts for factors affecting the beam and concrete slab over time.
00:03
In Structural Bridge Design, once you design a beam, there are several types of loads to consider.
00:10
One of these is environmental loads, such as a differential temperature profile.
00:16
This type of load accounts for the temperature variations within the structure, which can cause expansion and contraction of materials.
00:24
In this scenario, a composite, pretensioned, precast beam
00:29
and a 21-meter-long, 2-meter-wide concrete slab are designed, with dead loads, construction loads,
00:36
and live loads already applied.
00:40
The next step is to create a differential temperature profile, including the associated shrinkage and shear parameters.
00:47
When creating the profile, keep the following specifications in mind
00:52
to ensure that the beam design can accommodate temperature-related effects over time:
00:57
While primary stresses need to be calculated, there are no secondary effects due to temporary shrinkage, as the beam is statically determined.
01:06
The temperature profile applied should be based on the expected differential temperatures across the section
01:12
and should consider a surface finish of 100 millimeters thick.
01:16
The concrete is expected to have a total shrinkage strain of -0.00025,
01:23
with 20% of this shrinkage occurring before the in-situ slab is cast in place.
01:28
There is a differential shrinkage strain of -0.0001, and the concrete is expected to exhibit creep behavior with a creep coefficient of 1.5.
01:41
With the beam design open and Design Beam activated in the Navigation Pane, in the navigation toolbar, click Analyse.
01:50
In the Pre-tensioned Beam Analysis form, expand the Analyse for drop-down and select Differential temperature primary stress.
01:59
This opens the Differential Temperature Analysis form, along with a preview in an additional graphics window.
02:07
In this form, adjust the Type to Non Linear, change the Type of Deck to Type 3b: concrete beams, and set the Surfacing thickness to 0.1.
02:18
Then, click OK to accept the differential temperature profile.
02:22
Back in the Pre-tensioned Beam Analysis form, expand the Set parameters for drop-down and select Time dependent effect calculations.
02:32
In the form that opens, enable shrinkage strain and set it to .000251504.
02:41
Then, enable and set Long term losses to 20%, differential shrinkage to .0001, and creep coefficient to 1.5.
02:52
Click OK to save these parameters.
02:55
Back in the Pre-tensioned Beam Analysis form, set the Exposure to XD1, and then click OK.
03:04
Creating a differential temperature profile with associated shrinkage and shear parameters
03:09
accounts for factors affecting the beam and concrete slab over time.
