Concrete member analysis design using ram software
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Transcript of Concrete member analysis design using ram software
Lecture 17 – Page 1 of 17
Lecture 17 – Concrete Analysis/Design using “RAM” Software RAM is a commercially available software package used for analysis and design of structures. It is very powerful and accurate. We will be using it to analyze and design the flexural reinforcing for a simply-supported reinforced concrete beam. EXAMPLE 1 GIVEN: A simply-supported 12” x 20” concrete beam uses f’c = 4000 psi and Grade 60 bars. All loads shown are factored, and includes beam weight. REQUIRED:
1) Draw and label the complete shear + moment diagrams. 2) Determine the minimum required area of tensile steel, assuming “d” = 18”. 3) Using RAM software, determine the support reactions and maximum moment. 4) Using RAM software, determine the minimum required area of tensile steel.
Step 1 - Draw and label the complete shear + moment diagrams.
1’-0”
R2= 14.0 Kips R1 = 22.0 Kips
22 kips 17 kips
1 kips
5’-0” 15’-0”
wu = 1000 PLF (incl. beam wt.)
16 Kips
0
-14 kips
0
98.0 Kip-ft 97.5 Kip-ft
Mmax = 98.0 Kip-ft
0 0
Lecture 17 – Page 2 of 17
Step 2 – Determine the minimum required area of tensile steel, assuming “d” = 18”.
Using Mmax = Mu, use 2bdM u
φ from Lecture 4:
where: Mu = 98 Kip-ft = 1,176,000 lb-in φ = 0.9 b = 12” d = 18”
2bdM u
φ = 2)"18)("12)(9.0(
1176000 inlb −
= 336.1 psi
Use ρ = 0.0059
12”
18” 20”
Lecture 17 – Page 3 of 17
Recalling bdAs=ρ
Solve for As = ρbd = (0.0059)(12”)(18”) Required As = 1.27 in2
Lecture 17 – Page 4 of 17
RAM Software
Step 1 – Create a model of the beam as shown below:
“Y” a
xis
“X” axis
16 Kips
5’-0” 20’-0”
Node 2 – Coordinates = 20’,0’ Roller end support
Node 1 – Coordinates = 0’,0’ Pinned end support
wu = 1000 PLF
Member 1
Nodes Tab
Members Tab
Lecture 17 – Page 5 of 17
Step 2 – Input coordinates for “Nodes” 1 and 2:
Step 3 – Define member 1 between Nodes 1 and 2:
“Nodal coordinates”
Type in coordinates here
Nodes Tab
Members Tab
“Connectivity and description”
Type in node numbers here
Lecture 17 – Page 6 of 17
Step 4 – Define support types at Nodes 1 and 2:
Nodes Tab
“Restraints”
Click on Node 1
Click on “Pinned, no translation”
Node 1
Lecture 17 – Page 7 of 17
Nodes Tab
“Restraints”
Click on Node 2
Click on “Pinned, translate in X”
Node 1
Lecture 17 – Page 8 of 17
Step 5 – Define member 1 “Section”:
Members Tab
“Sections”
Member 1
RcBeam
Double-click 12x20in
Lecture 17 – Page 9 of 17
Step 6 – Define member 1 “Materials”:
Members Tab
“Materials”
Member 1
Click “RC” (Reinf. Conc.)
Double-click C4-60.Mat (f’c = 4 ksi, grade 60 bars)
Lecture 17 – Page 10 of 17
Step 7 – Define member 1 “Loads on members”:
Members Tab
“Loads on members”
Member 1
Click “Distributed force (downward –y direction)”
Distributed forces
See “Distributed load” dialog box, next page
Lecture 17 – Page 11 of 17
Enter 1.0 here – notice that the units are [Kip/ft]
Click OK
See next page for input of point load on member
Lecture 17 – Page 12 of 17
Input concentrated load here:
Members Tab
Member 1
Concentrated forces
Click “Concentrated forces on members”
See “Concentrated loads” dialog box, next page
Additional concentrated loads may be added (or edited) here
Lecture 17 – Page 13 of 17
16 Kips point load
(see loading diagram)
Load is located 5’-0” from left end of member (see loading diagram)
Lecture 17 – Page 14 of 17
Step 8 – Save file, then “Analyze structure…”:
Click “Process”
Click “Analyze structure…”
Click “Analyze”
Lecture 17 – Page 15 of 17
Step 9 – View and print “Force Diagrams”:
NOTE: Shear diagram is shown upside-down relative to the convention we are used to.
Use slider bar to scroll along length of member dynamically see numeric results
Verify Mmax = 98 Kip-ft = same as hand analysis!!
Lecture 17 – Page 16 of 17
Step 10 – View and print “Reinforced concrete design…”:
See reinforced concrete analysis results, next page
Lecture 17 – Page 17 of 17
Flexure As = 1.32 in2 → compare with hand-
calculations As = 1.27 in2 → VERY CLOSE!!!