Moment Redistribution Coefficient
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Project Tutorial Design Codes Reinforced Concrete Deflection ACI MIDAS nGEN moment redistribution Flexural Resistance continuous beam Field_Structure Structure Type_Building Category_Knowledge Category_How-to Design Code_Eurocode Design Code_ACI
News & Trends Reinforced Concrete ACI updated code ACI318-19 ULS Design Field_Structure Structure Type_Building Category_Knowledge Category_Industry Design Code_ACI
The new ACI318 Code, ACI318-19 is similar with the previous code, ACI318-14 in the basic approach. but in the current documents, there are a number of significant differences.
Through this brief document, you can discover the differences between the two codes, and understand their factors and design concepts.
In this document, the comparison between ACI 318-19 and ACI318-14 Code has 8 classified sections.
1. New rebar material,
2. Minimum reinforcement provisions
3. New reinforcement strain limit
4. Significant updates to shear provisions
5. Hanger reinforcement provisions
6. New equation for Ie
7. Modification of development length provisions
8. Modification of earthquake-resistance provisions.
Also, the specific standards are based on the ACI318M-19 and ACI318M-14 as SI Units for US Codes.
News & Trends flat slab design flat slab beam element Field_Structure Structure Type_Building Category_Knowledge Design Code_ACI Design Code_KDS
The Building Structural Standard defines a two-way slab system as a concrete slab system in which two rebars are arranged in two directions regardless of the presence or absence of a beam that transmits a load to a column'. Also, in ACI 318, this is expressed as ‘slab systems reinforce flexure in more than one direction, with or without beams between supports’. Therefore, a two-way slab system refers to a slab system in which reinforcing bars are arranged for bending in two or more directions regardless of the presence or absence of beams in columnar rows'. Typical types of two-way slab systems commonly used today include two-way slabs with beams, flat plates, flat slabs, and waffle slabs.
Figure1. Typical Types of 2-Way Slab
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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 Field_Structure Structure Type_Building Category_Knowledge Category_How-to Design Code_ACI
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
News & Trends High-rise building Construction Stage Analysis Elastic Shortening Sequential Analysis Column Shortening Tall Building Long-Term Deflection Creep and Shrinkage Field_Structure Structure Type_Building Category_Knowledge Category_Case Study Design Code_ACI
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News & Trends two-way slab flat slab design strip method flat slab drop panel column capital Field_Structure Structure Type_Building Category_Knowledge Category_How-to Design Code_ACI
Tips & Tutorials MIDAS nGEN MIDAS GEN Field_Structure Structure Type_Building Category_Knowledge Category_Industry Design Code_Eurocode Design Code_AISC Design Code_BS Design Code_ACI Design Code_ASCE
Structure Insight P-Delta Analysis Geometric nonlinearity Buckling analysis 2nd order effect secondary structural behavior P-Delta effect Field_Structure Structure Type_Building Category_Knowledge Category_How-to Design Code_AISC Design Code_BS Design Code_ACI