20120703 Gen Advanced Webinar Construction Stage Analysis

8/10/2019 20120703 Gen Advanced Webinar Construction Stage Analysis

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Construction Stage Analysis withSpecial Emphasis on Column Shortening

midas Gen Advanced Webinar on

Webinar ObjectiveConstruction Stage Analysis

Column ShorteningProcedure for Construction Stage AnalysisUseful Features for Construction Stage AnalysisProject ApplicationsLive DemonstrationWhy midas Gen



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Webinar Objective





midas Gen Webinar One Stop Solution for Building and General Structures

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Introduction

Objective

1. Introduction to Construction Stage(CS) Analysis.

2. Introduction to Column Shortening.

3. Discussion of Features available in midas Gen for CS Analysis.

4. Live demonstration of performing CS analysis on a 40 Storey RC Building

and interpretation of Column Shortening results.

5. At the conclusion of the webinar, familiar with construction stage

analysis, column shortening phenomenon and midas Gen applicability to

those issues.



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Construction Stage Analysis






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Why Construction Stage (CS) Analysis

1. General analysis is performed under the assumption that all loads are simultaneouslyapplied to a completed structure.

2. This assumption is not valid in a real construction sequence because building is

constructed floor by floor and dead load acts sequentially .

Construction Sequence

Self weight ofslab

Other Dead Loads (Part ions,Finishes)

Completed Structure

Dead Load + LiveLoad

Wind

Earthquake

LL,WL,EQActs




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Conventional analysis Vs CS Analysis

Case 1 – ConventionalAnalysis

Case 2 – CSAnalysis

Stage 1 Stage 2




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Conventional analysis Vs CS Analysis

Case 1 – ConventionalAnalysis

Case 2 – CSAnalysis




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Where CS Analysis is Required?

Long Span Trusses

Long Span Slabs, Beams constructed in multiple stages

Prestressed concrete Structures

CS analysis should be performed for all structures where there is a change inSupport Conditions, Loading and varying material properties (Concrete).



Column Shortening






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Column Shortening

Column Shortening

Elastic Shortening

Young’s Modulus is strictly applicable onlyto the Linear Categories.

E = (σ / ε) ΔL = (PL/A E)

σ

Decrease in the length under imposed loadwhich is linearly proportional to load.

Inelastic Shortening (Concrete Structures)

σ

Creep Shortening.Shrinkage Shortening.




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Column Shortening

Column Shortening

With increased height of structures the effect of column shortening (Elastic & Inelastic)

take on added significance and need special consideration in design and construction.

Elastic Shortening of 80 Storey Steel Structure ~ 180 mm to 255 mm.

Elastic Shortening of 80 Storey Concrete Structure ~ 65 mm.

Total Shortening of 80 Storey Concrete Structure ~ 180 to 230 mm.

Inelastic Shortening ~ 1 to 3 times Elastic shortening.




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Column Shortening

Effects of Column Shortening

Absolute shortening is rarely of practical interest.

Differential shortening between adjacent vertical elements is the most important

factor for engineer.

Axial Shortening of vertical elements

will not effect those elements very much,

horizontal elements like beams and slabs

and non structural elements are affected.




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Column Shortening


Cracks in Partition Walls. Cracks in Staircases Deformation of Cladding. Mechanical Equipment. Architectural Finishes. Built in Furnishings.

These non structural elements are notintended to carry vertical loads and aretherefore not subjected to shortening.

Slabs may not be truly horizontal after some time. Beams could be subjected to higher bending moments. Load transfer.

Structural Effects

Non Structural Effects




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Column Shortening


Deformation and breakage of Facades, windows &Parapet walls…

Reverse Inclination of Drainage Piping System

Deformation of Vertical Piping System Deformation and breakage of internal partitions




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Column Shortening

Movements related to construction sequence

• Pre-slab installation shortenings – Shortenings taking place up to the time of slab installation

• Post-slab installation shortenings – Shortenings taking place after the time of slab installation

: Compensation

: Design Level

: Pre-slab Installation shortening: Post-slab Installation shortening




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Column Shortening

Procedure for Accounting Column Shortening Analytical Measurement

Reflection of physical properties in calculation frommaterial experiment:

Young’s Modulus, Poisson’s Ratio, MeanCompressive strength, Volume to Surface ratio,Shapes, sizes etc.

Reflection of effects of Climate on shortening: Average Temperature , RH etc.

Construction Sequence:Stage duration, Additional Steps, Member Age,Load activation age, Boundary activation age etc.

Reflection of the above effects on site master-schedule.

Installation of sensors or gages in members fordetermining the actual shortening.

Understanding and noting the following:Curing procedure / Temperature,

Actual Shortening,Change in Ambient Temperature (Important),

Actual Humidity,

Deviation from Defined Construction Stages,

Manipulation of factors in analytical Calculation,Re- Analysis…

Experimental Measurement

Using Software or Manually(Manual calculation is almost impossible)

Field Measurements

Method has Limitation




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Column Shortening

Compensation at Site

ColumnColumn

1 st correction

2nd correction

1st correction




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Procedure For CS Analysis

Performing CS Analysis in midas Gen

Define materials, sections

Assign Elements, Boundaries,Loads to the groups

Define Time Dependent Materials

Enter the Construction Stage AnalysisData

Perform Analysis

Check results for each ConstructionStage

Check Column Shortening

•Creep & Shrinkage•Compressive strength

•Specify the duration of CS•Activate/Deactivate elementgroups / boundary groups/ loadgroups




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Time Dependant Material Properties

Creep and Shrinkage Compressive Strength




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Construction Stage Analysis Data

0 day 10 day 20 day 30 day 40 day

Construction Stage Durat ion Construction Stage Duration

Activation orDeactivation of

element, boundary,and load

Activation orDeactivation of loadwith time span from

the stage start

Activation orDeactivation of

element, boundary,and load




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Column Shortening Graph

• Post-slab installation shortening (Subsequent

Slab)

• Pre-slab installation shortening (Up to slab )

• Total Shortening (Pre –Slab + Post –Slab)

[Column Shortening Graph ]



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Useful Features for Construction Stage Analysis






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Useful Features for CS Analysis

Building Model Generation Wizard

The wizard readily allows us to define the timing of elements created and loadings applied in theconstruction stages during the erection of a building.

You may find it more convenient to first click the [Automatic Generation] button to define the basic

construction stages and modify them as necessary.




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Construction Stage Analysis for Composite Members

Define an analytical model for each construction stage by assigning activated or inactivated sectionscorresponding to each construction stage of a composite section.

By using Composite Section for Construction Stage, we can consider the construction sequence with

creep and shrinkage effect.




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Spring Supports for Soil InteractionPoint Spring Support (Linear, Comp.-only, Tens.-only, and Multi-linear

type)

Surface Spring Support (Nodal Spring, and Distributed Spring)

Springs can be activated / deactivated during construction stage

analysis.

[ Nonlinear point spring support]

[ Nodal Spring and Distributed Spring] [ Surface Spring Support] [ Pile Spring Support]




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Tendon Loss

Ple-stress load can be considered in construction stage analysis.

Tendon primary / secondary forces are provided with pre-stress loss graph.



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Project Applications






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Burj Khalifa (Dubai, UAE)

Height 705 mNo. of floors 160Location Dubai, United Arab EmiratesFunction / Usage Office Building & Residential BuildingDesigner Adrian D. SmithArchitect Skidmore, Owings & MerrillGeneral Contractor Samsung Development

o v e r v

i e w

CS:1

CS:30




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SK S-Trenue (Seoul, Korea)

Area 39,600 m 2

No. of floors 36Location Seoul, KoreaFunction / Usage Office BuildingStructure Type Composite StructureFoundation Type Mat FoundationLateral load resisting system RC Core + Steel + RC Composite Frame

o v e r v

i e w




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Keangnam Hanoi Landmark Tower (Hanoi, Vietnam)

Height 345mNo. of floors 70 fl., 49 fl.Location Hanoi, VietnamFunction / Usage Hotel, Office, and Residential buildingStructure Type Reinforced Concrete StructureArchitect Heerim, Samoo, Aum & Lee, Hellmuth Obata + KassabaumContractor Keangnam

o v e r v

i e w



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Live Demonstration






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Live Demonstration

Structural Plan

Typical Floor Plan

Storey's :- 40

Storey Height :- 3.15 m

Total Height :- 126.85 m




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Live Demonstration

Material and Sectional Properties

Level fck

Size WallThk. C1 C2

1 st to 10 th 50 1200 x 1200 900 x 900 500

11th

to 20th

40 1000 x 1000 800 x 800 500 21 st to 30 th 35 800 x 800 700 x 700 500

31 st to 40 th 30 600 x 600 600 x 600 500

Girder 30 900 x 600 -

Link Beam 30 700 x 500 -




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Live Demonstration

Construction Schedule

Stage1

Stage4

Final Stage

Partition Load : 5 weeks after first slab casting.Finish Load : 5 Weeks after Partition WallConstruction.




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Live Demonstration

Steps

Time Dependant Material Properties•Define Creep and Shrinkage Properties .•Define time Dependant Material Properties.•Define Time Dependant Material Link.•Change Element Dependant Material Property

Define Construction Stage•Define Construction stages using Building Wizard for CS analysis

•Create LL group and add LL to LL group.•Define CS for LL

Perform Analysis

Results•BMD’s and SFD’s for different CS. •Deformations for different CS.•Column Shortening Graph.



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Why midas Gen





Q A

One Stop Solution for Building and GeneralStructures

http://en.midasuser.com/

20120703 Gen Advanced Webinar Construction Stage Analysis

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