What is Geometric Nonlinear Analysis?
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Tips & Tutorials Nonlinear Analysis Nonlinear Elements Analysis Manual for Midas/Gen
Time History Analysis Tips & Tutorials Response Spectrum Buckling analysis Analysis Manual for Midas/Gen
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Prestressed Concrete PSC Time Dependent Losses News & Trend Creep and Shrinkage Analysis Manual for Midas/Gen Post-Tensioned Concrete Instantaneous Losses Anchorage Slip Prestressed Concrete Analysis
Project Tutorial Analysis Manual for Midas/Gen Design Conditions
News & Trends Thermal Stress convective heat transfer Analysis Manual for Midas/Gen Pipe Cooling Accumulated Temperature Thermal Conductivity Heat Source Concrete Structure Heat of Hydration Analysis
OVERVIEW
In a certain concrete structure with considerable mass or where a construction progresses rapidly with a number of construction joints, the rate and amount of heat generation due to hydration are important. Non-uniform thermal expansion and contraction due to heat of hydration and cooling of concrete accompanied by changing constraints create undesirable stresses. The stresses may cause detrimental cracking in the concrete, thereby reducing its strength and durability.
Heat of hydration analysis thus becomes important when casting mass concrete structures. It enables us to predict and control temperature and stress distribution within a structure to avoid potential problems. Mass concrete structures requiring heat of hydration analysis depend on their dimensions, shapes, cement types and construction conditions.
In practice, hydration analyses are normally carried out for slabs or mats in excess of 800~1000mm in thickness and walls confined at bottom in excess of about 500mm. Surface cracking may develop initially due to the temperature difference between the surface and center. Through-cracks can also develop as a result of contraction restrained by external boundary conditions in the cooling process of high heat of hydration.
The heat of hydration analysis is largely classified into several sub-analyses. It entails temperature distribution analysis for conduction, convection, heat source, etc.; change in modulus of elasticity due to curing and maturity; and stress analysis for creep and shrinkage. The following outlines the various components affecting the analysis.
Contents
Project Tutorial Construction Stage Analysis Time Dependent Material Properties Creep and Shrinkage Analysis Manual for Midas/Gen
OVERVIEW
A building structure is typically constructed floor by floor in the case of a reinforced concrete structure or often constructed several floors at a time in the case of a structural steel structure. Even on the same floor, different parts are constructed at different stages.
A typical structural analysis entails applying the loads to the completed structure at once. This results in significant discrepancies as the scale of the building increase, especially as the number of stories increases. Regardless of the type of construction, construction dead loads on a particular floor are typically acting on the structure without the presence of the upper floors during the construction. This actually results in completely different column shortenings from the analysis results based on the “full loading on the completed structure”. The change of strength gain, creep and shrinkage in the case of reinforced concrete construction compound the discrepancies. MIDAS/Gen enables the engineer to account for the change of geometries and time-dependent material properties during and after the construction.
Each temporary structure at a particular stage of construction affects the subsequent stages. Also, it is not uncommon to install and dismantle temporary supports during construction. The structure constantly changes or evolves as the construction progresses with varying material properties such as modulus of elasticity and compressive strength due to different maturities among contiguous members. The structural behaviors such as deflections and stress re-distribution continue to change during and after the construction due to varying time-dependent properties.
Since the structural configuration continuously changes with different loadings and support conditions, and each construction stage affects the subsequent stages, the design of certain structural components may be even governed during the construction. Without such construction stage analysis, the conventional analysis will not be reliable.
Contents
Tips & Tutorials Tension-Only Elements Truss Elements Compression-Only Elements Analysis Manual for Midas/Gen Two-Dimensional Axisymmetric Element Element Stiffness Data Wall Element Axisymmetric Element Plane Element Solid Element
Structure Insight Tension-Only Elements Truss Elements Compression-Only Elements Analysis Manual for Midas/Gen Two-Dimensional Axisymmetric Element
Tips & Tutorials Cable Elements Tension-Only Elements Truss Elements Compression-Only Elements Analysis Manual for Midas/Gen Two-Dimensional Plane Strain Element Two-Dimensional Axisymmetric Element Element Forces