Detailing the reinforcement of beams from ETABS output
Detailed design of beams in Etabs 2018. The ETABS file for a G+4 building is provided. Perform the analysis and design of the RCC Moment ResistingFrame. The next challenge is specifically about two continuous beams on the 1st floor. 1) 3 spans of the continuous beam along grid A
Detailed design of beams in Etabs 2018.
The ETABS file for a G+4 building is included. Perform the analysis and design of the RCC Moment ResistingFrame. The next challenge is specifically about two continuous beams on the 1st floor.
1) 3 spans along grid A 2) 7 spans along grid 3
Then tackle the following issues.
Provide details of the longitudinal and transverse reinforcement for the two continuous beams. Sketch the height details of the beams or create a design with AutoCAD software. Below is an example of how the height of beams is set up in consultancies. The participants can set it up according to their own preferences:
Ans) given figure is analyzed using the control model, and the analysis is performed.
Then we get the different values for the steel surface of each beam, as shown below.
Bars calculation is done along grids A and 3.
The calculated number of bars is displayed in the AutoCAD interface, as shown in the figure.
Give the reasons for the failure of the middle span along grid A. What are the possible ways in which this problem can be solved?
Ans) There is no uniform span along grid A, which means that the load distribution is disrupted. to fix this.
All spans must be the same size. Therefore, the unequal length of the middle span compared to the other two leads to failure.
Calculate the value of the maximum shear force in one of the spans in both continuous beams, according to clause 6.3.3(b) in IS 13920 – 2016. Also, confirm these values using the shear demand calculated by ETABS. Note that if more longitudinal reinforcement is applied than required (according to the results of ETABS), the demand for shear forces will be different from what is given by ETABS.
Ans) After checking the model and performing the analysis, we get the values of the sample at each bar.
Right-click on a beam, and we get the table with details of the load combinations above and below.
After clicking details, we get the values for design power and factored design power.
The analysis is correct if the design force is greater than the calculated force.
How do I add beams to ETABS?
Semi-rigid beam-column connection
Both a hinge and a connection can be used to model a semi-rigid beam-column connection:
Hinge properties can be defined via Define > Section properties > Hinge properties, then they can be assigned to a selected frame object via Assign > Box > Hinges. The CSI Analysis Reference Manual (Chapter VIII Frame Hinge Properties) has additional details on frame hinges.
A connection can be assigned to a common panel zone by selecting the common connection at a beam-to-column connection and then assigning the common panel zone via Assign > Connection > Panel Zone. When modeling the panel zone, any connection property can be specified.
A connection can also be created manually by drawing the beam and column objects so that their ends are slightly apart and do not share a common connection. A connection property must then be defined to reflect the stiffness of the connection, and the offset connections must be connected using Draw > Draw 2 Connection.
How do you manually create a beam
Floor/ceiling beams and roof beams are not generated automatically; they can only be drawn manually.
There are three types of beams you can create in Chief Architect: floor, ceiling, and roof beams.
To make a beam
Open the plan where you want to add a floor or ceiling joist, select Edit > Default Settings, find and select the Framing category, then click Edit.
In the Beams panel of the Framing Defaults dialog box that opens, click the Edit Floor Beam Defaults button.
The Edit Floor Beam Defaults button in the Beams panel of the Select Framing Defaults dialog box.
In the Default Floor Beam window, set the default values as desired.
These are just the default values. You can constantly adjust an individual bar to deviate from the defaults once placed in your plan.
Once you are done with these changes, click OK to apply them, then repeat the process for roof beams.
Adjust the beam properties such as depth and width and type in the Beam Defaults dialog box
Then select Build > Framing > Floor/Ceiling Beam or Roof Beam, depending on the type of Beam you want to create.
Remember that the floor frame is drawn on the floor below the floor concerned. If you want to remove a floor beam for floor 1, draw this object on floor 0.
Click and drag to create the bar.
Then, using the Transform/Replicate or Multicopy editing tools, you can replicate the bar throughout the space or structure.
How do analyze a beam in ETABS?
Fully customizable graphical user interface
ETABS provides a single user interface for modeling, analysis, design, and reporting. There is no limit to the number of model windows, model manipulation views, and data views.
Enhanced DirectX images
DirectX graphics with hardware-accelerated graphics allow for model navigation with fly-throughs and fast rotations.
Users can view moment diagrams, load assignments, deflections, design output, and reports on a single screen.
Fast navigation and data management
The ETABS model explorer improves your possibilities to manage data in your model. You can define, duplicate and modify properties in groups and drag properties directly to the models for assignment. User-defined views can be easily set in the model explorer for quick navigation.
Wide range of templates for fast model generation.
ETABS has a wide selection of templates to quickly start a new model. At this stage of the model, you can define the grid and grid spacing, the number of floors, the default structural system sections, default slab, and slab sections, and uniform loads (specifically dead and live loads).
The physical model consists of objects that represent the physical construction parts. Views of the physical model accurately reflect the insertion points, the orientation of the elements, the intersections of the objects, and other geometric details of the object model.
Views of the analytic model show the finite element model of the structure, which consists of the connections of the joints, frames, and shells and the defined meshes. When the analysis is run, the analytic model is automatically generated from the model and its mappings and settings.
One of the most powerful features that ETABS offers is floor recognition, which allows building data to be entered in a logical and convenient way. You can define your models by floor and by floor, analogous to the way a designer works when creating blueprints.
Improved design tools
Intelligent snaps make model generation easy by automatically detecting intersections, extensions, parallels, and perpendiculars. Simply import an architectural DXF/DWG into the background of the ETABS modeling window and use it as a template to trace over to help you build your model. Toggle layers on and off to choose which layer or layers you want to see. You can also right-click on an element to quickly convert an area into an ETABS construction object.
Multiple Grid System Definition
In ETABS, grids can be defined as Cartesian, cylindrical, or general free-form grid systems. There is no limit to the number of grid systems in a model, and they can be rotated in any direction or placed at any origin in the model.
Developed increments for generating custom increments
Developed elevations can view any drawn path on a map. This is especially useful for raising a facade with a unique shape. Once the developed elevation is drawn, it is added to the list of elevations in the model.
Comprehensive Interactive Database Editing Tool
CSI software stores model data and other information in database tables that can be directly edited via interactive database editing. This powerful feature allows models to be developed or edited quickly.
Model explorer functionality
The model explorer provides easy access to the model definition data, including property forms, load definitions, and object forms, as well as the analysis and design results in graphical, tabular, and report forms.
Wide range of Meshing tools
Engineers have many options when it comes to mesh generation in ETABS. Simply select the area object and then select the rules for the automatic mesh generator. It is also possible to mesh objects manually in the model. This is called external meshing. This results in a one-to-one correspondence between objects and elements.
Section Properties / Section Designer
ETABS has a built-in library of standard concrete, steel, and composite cross-section properties from both US and international standard cross-sections. Section Designer is an integrated tool built into SAP2000, CSiBridge, and ETABS, that enables the modeling and analysis of custom cross-sections.
What is the design procedure for design of beam?
Reinforced concrete beams are structural elements designed to support external transverse loads. The loads cause bending moments, shear forces, and in some cases, torsion along their length. In addition, concrete is strong in compression and very weak in tension. Therefore, steel reinforcement is used to absorb tensile stresses in reinforced concrete beams. In addition, beams support loads of slabs, other beams, walls, and columns. They transfer the loads to the columns that support them. In addition, beams can be simply supported, continuous, or cantilevered. They can be designed as rectangular, square, T-shaped, and L-shaped sections. Beams can be single or double-reinforced. The latter is used when the depth of the beam is limited. Finally, this article presents the design of a rectangular reinforced concrete beam.
Before starting the design of a reinforced concrete beam, certain assumptions must be made. These guidelines are given by certain codes and researchers. It should be known that the designer’s experience plays an important role in making these assumptions.
Beam depth (h)
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There is no unique procedure for calculating the total beam depth (h) for the design. However, certain guidelines can be followed to calculate the beam depth to meet the deflection requirements.
ACI 318-11 proposes a minimum thickness for unsupported beams unless deflections are calculated. t
The Canadian Standard Association (CSA) provides a similar table, except for one continuous end, which is 1/18.
Table 1 minimum thickness of unsupported beams unless deflections are calculated
Minimum thickness, h
Easily supported One end continuous Both end continuous Joist
Members not supported on or attached to partitions or other structures liable to be damaged by large deflections
l/16 l/18.5 l/21 l/8
Notes: The values given are to be used directly for normal-weight concrete elements and class 420 reinforcement. For other conditions, the values are modified as follows: a) For lightweight concrete with an equilibrium density (WC) between 1440 and 1840 kg/m3, the values multiplied by (1.65 – 0.0003wc) but not less than 1.09. b) For fy other than 420 MPa, the values are multiplied by (0.4 + fy/700).
The depth of the beam can also be estimated from the span/depth ratio. IS 456 2000 provides the span-to-depth ratio to check the deflection of the beam, as shown in Table 2.
Table 2 span/depth ratio based on span and beam type, IS 456 2000
Span Beam Type span/depth ratio
Up to 10m, Single supported 20
More than 10m Easily supported 2010/span wishbone – Continuous 2610/span
Width of the beam (b)
The ratio between the beam depth and the beam width is preferably between 1.5 and 2, the upper limit being 2. The placement of the reinforcement is one of the most important factors determining the beam width. Therefore, when estimating the beam width, the minimum distance between the bars must be taken into account. The width of the beam must be equal to or less than the size of the column supporting the beam.
ACI 318-11 provides a minimum and maximum reinforcement ratio. The reinforcement ratio is an indicator of the amount of steel in a cross-section. Any value between this range can be used for the design of the beam. Nevertheless, the choice is influenced by the required ductility, construction, and economic considerations. Finally, it is recommended to use a 0.6*maximum reinforcement ratio. The reason for this is that such rods cause bending cracks and require a greater length to develop their strength. However, the placement costs of large bars are lower than the placement costs of a large number of small bars. In addition, the common bar sizes for beams range from NO.10 to NO.36 (SI unit) or NO.3 to NO.10 (common US unit), and the two larger diameter bars, NO.43 (NO.14) and NO.57 (NO.18) are used for columns.