Beam Section Temperatures

Enter the temperature differences between specific locations of beam for thermal stress analysis. The vertical temperature gradient is considered in concrete and steel superstructures with concrete decks, which are subject to temperature difference due to direct sun light and shade.

A temperature difference may be also defined by the Temperature Gradient function. In case of Temperature Gradient, only the temperature difference between the top and bottom of a section can be entered. However, in case of Beam Section Temperature, temperature differences for certain locations in a section can be entered.

- General Section Type

If a section for which a temperature difference is considered is not a rectangle, the section should be transformed into an equivalent rectangular section, which produces the identical moment due to the temperature load. And then the user needs to input the width and height of the equivalent rectangular section.

PSC Section Type

For PSC sections (except for Value type PSC sections) and Composite sections, which are relatively complex but frequently used, the program automatically defines the temperature load by dividing and transforming the corresponding zone. In case of PSC section as shown in the figure above, the transformed rectangular zone can be automatically calculated by selecting the PSC/Composite option instead of manual calculation.

From the Main Menu select Load > Temp/Prestress > Beam Section Temp.

Load Case Name

Assign the load case name. Click to the right to enter additional load cases and modify or delete existing load cases.

Load Group Name

Select the desired Load Group Name. Click to the right to enter additional load group names and modify or delete existing load group names.

Options

Add: To enter new or additional partial temperature loads to beam elements

Replace: To replace previously entered temperature loads

Delete: To delete previously entered temperature loads

Section Type

General: Select when inputting the temperature difference between the top and bottom of a General Section.

Note

If the section for which the temperature difference is to be considered is not a square, the section should be transformed into an equivalent square section having the same area and centroid as the original section.

PSC: Select when inputting a temperature difference in a PSC section type beam element

- When General Section Type is selected

Direction

Local-y: Temperature difference in the direction of ECS y-axis

Local-z: Temperature difference in the direction of ECS z-axis

Ref. Position

Assigns a reference position in the beam. The distance 'H' is measured from this reference position, and the temperature load is assumed to be applied at location 'H'.

Centroid: Centroid in the beam

+End(Top): The upper extreme fiber of the beam

-End(Bot.): The lower extreme fiber of the beam

Section Temperature

Initial Temperature
Specify the initial temperature in Structure Type.

Material
Define the material properties of the beam elements.

Element: Apply the material property information of the selected beam elements.

Input: Define the material properties to be applied to the thermal stress analysis.

Elast.: Modulus of elasticity

Therm.: Thermal expansion coefficient

B: Width being considered for temperature difference. If a section for which the temperature difference is to be considered is not a rectangle, the section needs to be transformed into an equivalent rectangular section.

H1, H2: Distance from the Ref. Position to the locations where the temperatures are defined

T1, T2: Temperatures at H1 and H2 respectively

Click to add the input data to the list. To modify the data, click after selecting and revising the relevant data. is similarly used.

Note
When a temperature load is applied linearly to structural elements, self-restrained stresses do not occur. However, if a nonlinear temperature load is applied to structural elements, self-restrained stresses may take place. Such internal retrained stresses occur without the presence of external restraints causing residual stresses internally.

- When PSC Section Type is selected.

Apply by Code Provision:

Check on this option to apply temperature gradient to the section according to the code provision. PSC, composite PSC and composite steel section are supported depending on the selected code. General sections imported from SPC are not supported.

SNiP / SP

Composite steel section is only supported.

IRC6: 2017

As per IRC6:2017, the user can provide the temperature gradient for PSC and Steel Composite girders for the positive and the reverse temperature difference.

(1) Temperature Gradient (Positive/Reverse) for Concrete sections

(2) Temperature Gradient (Positive/Reverse) for Steel Composite sections

AASHTO LRFD 2020

As per 3.12.3 of AASHTO LRFD, the user can provide the temperature gradient for PSC and Steel Composite girders for the positive and the negative temperature difference.

(1) Temperature Gradient (Positive/Negative) for Concrete sections

(2) Temperature Gradient (Positive/Negative) for Steel Composite sections

Eurocode

As per 6.1.4.2 of EN 1991-1-5: 2003, the user can provide the temperature gradient for PSC and Steel Composite girders for the heating and the cooling temperature difference.

(1) Temperature Gradient (Heating/Cooling) for Concrete sections

(2) Temperature Gradient (Heating/Cooling) for Steel Composite sections

AS 5100

As per 18.3 of AS 5100.2: 2017, the user can provide the temperature gradient for PSC and Steel Composite girders for the positive and the negative temperature difference.

(1) Temperature Gradient (Positive/Negative) for Concrete sections

(2) Temperature Gradient (Positive/Negative) for Steel Composite sections

Section Temperature

Initial Temperature
Specify the initial temperature in Structure Type.

Material
Define the material properties of the beam elements.

Element: Apply the material property information of the selected beam elements.

Input: Define the material properties to be applied to the thermal stress analysis.

Elast.: Modulus of elasticity

Therm.: Thermal expansion coefficient

Ref :Select a reference position at which the temperature load is acting. The distance 'H' is defined from this reference position to the position at which the temperature load is acting.

B: Width being considered for temperature difference. For Value type PSC section, the user should manually input the width of the equivalent square section. For other PSC and Composite sections, width shall be automatically calculated.

H1, H2: Distance from the Ref. Position to the locations where the temperatures are defined. Enter the distance directly or specify the distance using Shear Check positions (Z1, Z2 & Z3) in Section .

T1, T2: Temperatures at H1 and H2 respectively

Click to add the input data to the list. To modify the data, click after selecting and revising the relevant data. is similarly used.

Calculation of Beam Section Temperatures in PSC Section and Composite Section (Composite T, Composite I)

Divide the section to which the temperature load is applied into ten segments (Max. height = 0.1m). Here, the section must be divided at curved positions, boundary of the Part and boundary between Flange and Web in the composite section as shown in the figure below. Calculate property of each segment using the same procedure performed in General Type. The top and bottom of the segment rectangle corresponds to H1 and H2 in the General Type, respectively. The temperature of each segment is calculated assuming that the temperature load applied at T1 and T2 varies linearly. The final result is calculated by combining the results from each segment. This is equivalent to applying the temperature load ten times in the original method.

The method of calculating Beam Section Temperatures for PSC Section Type

Revision of Civil 2014 (v2.1)

Q1. How Beam Section Temperature load should be applied for tapered section as we cannot define different temperature variation for i-end, middle, and j-end separately?