Design Considerations during Construction

June 15, 2021
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OVERVIEW

There are cases where the design must be satisfied for two or more conditions for the same structure. In general, the design needs to be performed considering the load during construction and the load in use at the same time, as shown below. In this document, I will introduce  how to perform two analyses simultaneously.

 


 

Case 1 : During Construction

 

 

09_analysis case_case 1

Case 2 : In Use

 

09_analysis case_case 2-1

   

Modeling

 

Step 1 : Add & assign a member set.

 

 

09_analysis case_case_modeling step 1 & 2

    1) Click 'Add Member Set'.

    2) Add new member set of 'Structure_01~02'.

 

09_analysis case_case_modeling step 3     3) Assign the base members to 'Structure_01' by Selecting the members and             dragging in a model tree.

 

 

 

Step 2 : Add jack support members & assign a member set.

 

 

09_analysis case_modeling step 2_1

09_analysis case_modeling step 2_2

    1) Add a members of jack support in the model.

    2) Select the members of jack support.

    3)Assign the members of jack support to 'Structure_02' by dragging in a               

          model tree.

 

 

 

Loading

 

Step 3 : Create a slab loads.

 

 

 

09_analysis case_modeling step 3_1-109_analysis case_modeling step 3_2

    1) Define 'Static Load Set'.

    2) Create 'Self-weight' of slabs.

    3) Add a slab load for each cases.

 

 

Step 4 : Assign a slab loads to slab members.

 

 

09_analysis case_modeling step 4    1) Run 'Slab Load'.

    2) Assign the slab load for 'In Use' to slabs.

    3) Assign the slab load for 'In Construction' to slabs.

 

Step 5 : Create 'Support Set'.

 

09_analysis case_case_modeling step 5_1
09_analysis case_case_modeling step 5_2

 

    1) Run 'Slab Lod'.

    2) Assign the slab load for 'In Use' to slabs.

    3) Assign the slab load for 'In Construction' to slabs.

 

 

Setting of boundary condition

 

Step 6 : Assign the support set to columns.

 

09_analysis case_case_modeling step 6-1

    1) Run 'Ad Support' in Analysis tree.

    2) Assign the support for 'In Use' to slabs at the bottom of RC columns.

    3) Assign the support for 'In Construction' at bottom of jack supports      

          members.

 

Running an analysis

Step 7 : Create an analysis cases.

 

09_analysis case_case_modeling step 7_109_analysis case_case_modeling step 7_209_analysis case_case_modeling step 7_3

 Select each applied member, load, and boundary condition to create an analysis case.

 

 

 

Running an analysis : Checking Result

 : According to the load and boundary conditions, the results for each analysis case are different, as shown below.

 

09_analysis case_case_modeling step checking result_109_analysis case_case_modeling step checking result_2Running an analysis : Checking Result

 

09_analysis case_modeling checking result_1            Case 1 : During Construction

 

09_analysis case_modeling checking result_2

            Case 2 : In Use

 

09_analysis case_case_modeling step checking result_3

 

Running a design

Step 8 : Create a design cases.

 

09_analysis case_case_running a design step9-1   Design Case 1 : During Construction                                   Design Case 2 : In Use

 

09_analysis case_case_running a design step8_2 Combined design case

: It performs the design considering both Design Case 1 and 2. 

 09_analysis case_case_running a design step8_3

     1) Two design cases are crated according to each analysis case.

    2) Create a combined case for two design cases.

 

 

Running a design : Checking design result

 Each design case has a different number of main rebars.

 

09_analysis case_case_modeling step checking design result_1

 

 

       Design result by 'During Construction'                                 Design result by 'In Use'

09_analysis case_case_modeling step checking design result_2

                                                            Design result by 'During Construction'

09_analysis case_case_modeling step checking design result_3In the combined design case results, the reinforcement was recalculated considering the results for both design cases.

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About Author
Yeong-il Seo | Principal Structural Engineer

Young-il has over 13+ years of experience in building design, especially high-rise buildings with column reduction analysis, plant structures, pushover analysis, health monitoring, and vibration control projects. Since 2016, he is planning and providing technical supports for midas building products such as midas Gen, nGen, and Design+.

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