United StatesACI 318-19
#### Summary & Graphs
Access the full PDF file of the results of this calculation here: [Task 1](https://s3.amazonaws.com/helpscout.net/docs/assets/5c09df402c7d3a31944ed720/attachments/5ff5137cfd168b7773531eac/US-Concrete-Beam---B1.pdf)
## Method & scope
| Property | Detail |
| ---------------- | ----------------------------------------------------------------- |
| Design standards | ACI 318-19 |
| Regions | United States |
| What it checks | Flexural capacity, Shear capacity (ACI 318-19 update), Deflection |
#### Design Criteria
##### A. Absolute Deflection Limit
The hard maximum deflection allowed for the beam, regardless of span length. Normally, your local building code will dictate this. For the IBC, Table 1604.3 provides the limits.
##### B. Live/Short-Term Deflection Limit
Calculated independently for each span. For cantilevers, “L” is taken to be twice the length of the cantilever. Normally, your local building code will dictate this limit. For the IBC 2018, Table 1604.3 provides the limits.
##### C. Long-Term Deflection Limit
Long term deflection limit, including creep effects etc.
##### D. Simplified DL+LL Deflection Limit
Calculated independently for each span. For cantilevers, “L” is taken to be twice the length of the cantilever. Normally, your local building code will dictate this limit. For the IBC, Table 1604.3 provides the limits.
#### See the exact clause
**A. Beam Dimensions**
The figure given below illustrates the three parameters that need to be specified in this section.
* Cross-section height (h) must be specified in inches.
* Cross-section width (b) must be specified in inches.
* Total length of the beam (L) must be specified in feet.
**B. Concrete Strength**
The strength of the concrete being used must be specified in Pounds per Square Inch (psi). Concrete strength cannot be less than 2500psi.
**C. Concrete Weight Classification**
The concrete weight classification needs to be selected from the drop-down menu shown below.
Note that one can select 'custom' and input the concrete density and a lightweight concrete factor to create their own concrete weight classification.
**D. Reinforcement Strength**
Strength is limited to 80 ksi for regular columns, and 60 ksi in special seismic systems. This requirement is imposed to ensure steel yields before concrete crushes in the column.
**E. Concrete Cover**
Distance from concrete surface to edge of ties. Minimum cover: 1-1/2” for unexposed members, 2” for exposed members with bars >= #6, and 3” for any concrete cast against the ground.
**F. Position of Supports from Left**
For this section, the above table must be filled out as follows:
* In the first column, the support type must be selected from the drop-down menu
* In the second column, the location of the support must be specified in feet as measured from the left of the beam.
Tension Bars vs. Compression Bars**
Tension bars are the reinforcement bars which are in tension when the concrete beam is subjected to vertical loads. These are located towards the bottom of the cross-section (indicated in green in the figure below). Compression bars are the reinforcement bars which are in compression when the concrete beam is subjected to vertical loads. These are located towards the top of the cross-section (indicated in blue in the figure below.)
**A. Tension (Bottom) Bars**
This section allows the user to add rows of tension bars using the following table. Each row in the table corresponds to a new row of tension bars.
* In the second column, the number of bars in the row must be specified.
* In the third column, the size of the bars must be selected from a drop-down menu which has imperial sizes from #2-#18. For further information regarding Imperial dimensions of rebars visit: [https://www.engineeringtoolbox.com/reinforcing-bar-us-imperial-d\_1482.html](https://www.engineeringtoolbox.com/reinforcing-bar-us-imperial-d_1482.html)
* In the fifth column, the depth corresponding to each row must be specified. Depth is the distance from the row to the top surface of the concrete beam.
**B. Number of Compression (Top) Bars**
The number of compression bars must be specified. The default has been set to two, to provide anchors for stirrups.
**C. Compression Reinforcement Size**
The size of the compression bars must be selected from a drop-down menu which has imperial sizes from #2-#18. For further information regarding Imperial dimensions of rebars visit: [https://www.engineeringtoolbox.com/reinforcing-bar-us-imperial-d\_1482.html](https://www.engineeringtoolbox.com/reinforcing-bar-us-imperial-d_1482.html)
**A. Include Stirrups?**
A Stirrup is a closed loop of reinforcement bar, which holds the main reinforcement bars in place. In this section, the user can specify whether or not to include stirrups in their design. Stirrups are required if more than half the concrete shear strength is utilized.
**B. Stirrup Size**
The size of stirrups must be selected from a drop-down menu which has imperial sizes from #2-#18. For further information regarding Imperial dimensions of rebars visit: [https://www.engineeringtoolbox.com/reinforcing-bar-us-imperial-d\_1482.html](https://www.engineeringtoolbox.com/reinforcing-bar-us-imperial-d_1482.html)
**C. Number of Legs per Stirrup Bundle**
The number of rebars per loop must be specified. Enter 0 if no stirrups are present. The default is set to two.
**D. Stirrup Spacing at Supports**
Spacing between stirrups at the supports. Note that as shear will typically be much lower at midspan under a UDL, this spacing may change. This sheet is intended to provide basic design info only, but the shear force diagram may be used to check additional spacings.
**A. Distributed Loads**
The table in this section prompts the user to input distributed loads. For further instructions on how to fill out this table, check out our help article on how to input distributed loads.
**B. Point & Moment Loads**
In this section, the table must be filled out as follows:
* In column 1, the user can name the load as they prefer.
* In the second column, the location of the load must be specified in feet as measured from the left end of the beam.
* The following table will appear when one clicks on the third column.
The load type must be selected from the drop-down menu given. If it is a vertical load, its magnitude must be specified in pounds (lb). If it is a moment load, the magnitude must be specified in Pounds feet (lb.ft).
**C. Include Self-Weight?**
The user can choose whether or not they include the self-weight of the beam in their calculations. The calculator is set to include the self-weight by default unless the user specifies otherwise.
**D. Use Reduced Companion Live Load?**
The user can select whether reduced companion live load is used in their calculations or not. For live loads under 100 psf which are not in a garage or a place of public assembly, a 50% reduction in the live load is allowed when it is used as a companion load.
**E. Sustained Duration Factor**
A factor which accounts for the effects of creep in concrete. In most structures, the design life should conservatively remain at 5+ years. Sustained duration factor must be selected from the drop-down menu given below.
