# Method 2: Simplified Event Sequence + Rigorous Creep and Shrinkage Allowance

In Method 1 we used a simplified event sequence (without addressing the possibility of early age loading), to see how a single multiplier can be applied to allow for the combined effects of creep and shrinkage.

In **Method 2** we will re-use the same model, but edit the previous simplified
event sequence so that creep is considered in the cracked section analysis. The
multiplier will also be edited so that it only considers shrinkage effects.

# Download and open the tutorial model (if required)

# Establish some slab reinforcement

Prior to running a Slab Deflection Analysis, a reasonable level of slab reinforcement should already be provided. This can be achieved by designing all slabs and patches as follows:

- From the Analyze toolbar, click Analyze All (Static)
- From the Design toolbar, click Design Slabs
- From the Design toolbar, click Design Patches

# Set up the rigorous creep and shrinkage allowance

In this method the **Allowance
for Shrinkage Effects** multiplier is set to allow for shrinkage only.

# Edit the Event Sequence to ensure that creep is accounted for in the analysis

# Review the Restraint Constant

# Perform Iterative Slab Deflection Analysis

# Adjust the Restraint Constant and Re-analyze

Initially the Restraint Constant was set assuming significant restraint; we will now investigate the effect of assuming insignificant restraint.

# Generate Composite Modulus Report

An effective composite modulus report can be
obtained by right clicking a slab and choosing **Export Eff. modulus report to
Excel**. The report details the composite modulus E_{c} determined for
each event.

**To display the Composite
Modulus Report:**

# Summary of Results

Using the Simplified event sequence plus rigorous creep plus shrinkage allowance method, the results can be tabulated below:

Approach | Restraint Constant for Modulus of Rupture | Creep approach |
Assumed Shrinkage % |
Total deflection (Final load event) |
---|---|---|---|---|

ACI 435 (creep included in analysis) | 4.0 |
C h = 2 and χ = 0.8 |
25% | 1.5” |

ACI 435 (creep included in analysis) | 7.5 |
C h = 2 and χ = 0.8 |
25% | 1.0” |

# Next steps

- In Method 3 a modified version of the model using a detailed event sequence is investigated.
- Having obtained results for all three methods, observations on the different methods are discussed.
- Finally, using results from one of the methods, deflection checks are performed using check lines and an output report is generated.