CONTENTS
© Central Computing Facility 1997
All rights reserved: no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or any means, electronic, mechanical, photocopying, recording or otherwise, without prior written permission of the publisher except in the case of brief quotations embodied in critical articles and reviews.
Although best efforts have been made in preparing the program and the manual, no warranty of any kind is made, expressed or implied, respecting the program or the manual. Neither Central Computing Facility nor the publisher shall be liable to the purchaser or any other person or entity with respect to liability, loss, or damage caused or allegedly to have been caused directly or indirectly as a result of the usage of the program or the manual.
Publisher
Rudra Nevatia
137 Marine Drive
Bombay 400 020
Tel. (+91-22) 281 5014
The program ARCI designs reinforced concrete elements by the strength design method as specified in chapters 10 and 11 read with Appendix B of ACI 318-95.
Strength design procedures involve designing a section for the most critical state and checking to ensure that serviceability requirements are met. More often than not, strength is the governing design condition while serviceability requirements such as deflection and cracking are of secondary importance. The program therefore takes into account only the strength requirements.
It may be emphasized that this program addresses specific phenomena such as flexure, compression, shear and torsion and not structural systems such as slabs, walls, footings etc.
If some of the requirements of ACI 318-95 are not covered, it is to simplify data entry. The exceptions are listed in the relevant sections of the manual.
A distinguishing feature of this program is that it can design sections of arbitrary polygonal shape. This aspect is further elaborated in the following section.
The program may be used as a stand-alone package or as post-processor to a space frame analysis program.
This program requires an IBM PC compatible machine with at least 640 KB RAM, one floppy drive, monochrome monitor and keyboard running under DOS 2.1 or later. A hard copy of the output may be obtained on an eighty column dot matrix printer or an A4 size laser/bubble jet printer.
In order to save you the trouble of learning another word processor, no editing features are included in this program. You may use your favorite word processor to create a batch mode input file and to view output before printing.
The graphic output from this program is in DXF format. You may use any software which can import this format to generate a 2-D drawing.
There are no restrictions on the number of elements that can be designed in a single run. Each element may be designed for any number of load combinations. However certain restrictions apply to element cross sections and stations along elements as follows:
Maximum number of section types
99
Maximum number of segments per section type 99
Maximum number of bars per section type
99
Maximum number of stations per element
21
ACI 318-95 lays down specific rules for design of elements for shear and torsion which may be applied to all shapes of cross-section. On the other hand, design for axial load and flexure must be carried out from first principles. Guidelines are available in the code as well as numerous texts for designing regular cross-sections. Design of arbitrarily shaped sections requires special techniques, a brief description of which follows:
Several programs are available which analyze arbitrarily shaped RCC sections for flexure and axial load. Analysis of section involves calculation of axial load and bending moment which can be sustained by the section having a known area of reinforcement. The result is presented in the form of interaction curves. For example, the charts in SP:17A(90) are produced using an analysis program. Selecting reinforcement from charts can be time consuming and prone to errors.
Yet another category of programs design symmetrical RCC sections. For a given set of axial load and bending moments about the axes of symmetry, area of reinforcement is calculated satisfying interaction equation such as the one given in Section R10.3.6 of ACI 318-95. Apart from being restricted to symmetrical sections, such programs must necessarily introduce an element of error in the choice of the interaction equation.
A third category of programs design arbitrarily shaped sections using a rectangular stress block. The stress block parameters for a non rectangular section is by no means a trivial task. Apart from being a source of error, a rectangular stress block poses other problems such as non-convergence of solution.
In contrast, ARCI designs arbitrarily shaped RCC sections with or without voids, acted upon by axial load and arbitrarily oriented moment vector using a parabolic + linear stress block.
The basis for design of any section is equilibrium of applied actions with internal stresses. Now, internal stress is a function of location and orientation of neutral axis which in turn is a function of area of reinforcement. The resulting equilibrium equations are therefore non-linear.
The task of setting up of equilibrium equations is achieved by numerical integration while an iterative technique is used for their solution.
Direct search and Newton-Raphson method are the two most common techniques for solving non-linear equations. Direct search is slow while Newton-Raphson procedure may diverge. A tangent stiffness convergence formulation is adopted here whereby a solution is usually obtained within eight cycles.
The solution of equations ensures equilibrium of applied bending moment with internal stresses about axes perpendicular as well as parallel to the vector of applied moment. The resulting orientation of neutral axis may be at an angle to the vector of applied moment for unsymmetrical sections.
Often, equilibrium is sought only about the axis parallel to the vector of applied moment. For example, this situation arises when edge beams are designed as L sections with an effective width of slab forming the flange. Strictly speaking, an L section loaded in a vertical plane passing through its center of gravity will deform both in the vertical and horizontal planes to satisfy equilibrium. However, an edge beam is constrained to deform only in the vertical plane due to the high rigidity of slab in the horizontal plane. It is therefore proper that an edge beam should be designed ignoring equilibrium of internal stresses about the vertical axis. The program senses this exceptional condition and takes appropriate action when axial force, torsion, bending moment about minor axis and shear parallel to major axis are all zero for an element.
The program is based on the assumptions listed below. The first four assumptions are as stated in Section 10.2 of ACI 318-95 while the last three assumptions are specific to this program.
The element axes are oriented by the right hand screw rule as follows:
As the element's cross-section is viewed along its longitudinal axis, end 1 of the element is farther from the viewer.
+x-axis points horizontally towards the viewer
+y-axis points horizontally towards the viewer's right
+z-axis points vertically upwards
Forces and moments at a section are positive when acting along positive directions. Thus, tensile force is positive and bending moment about y-axis causing tension on the upper face is positive.
For sections subject to flexure without axial load, the concept of upper limit on tensile reinforcement is replaced with an upper limit on the depth of neutral axis as 0.375d ensuring that the section is never compression-controlled. It is easy to verify that for this limiting value of the depth of neutral axis, the strength reduction factor is 0.9.
When the required area of reinforcement is more than the tension-controlled value, the section is designed as doubly reinforced. The compressive reinforcement ensures the same level of ductility as for a singly reinforced section. The strength reduction factor therefore remains as 0.9.
For sections subject to flexure with axial load, the depth of neutral axis is governed by the equilibrium of applied force and moment with internal stresses. The maximum net tensile strain in steel determines the strength reduction factor to be applied to the section.
Section B.8.4 of ACI 318-95 permits redistribution of negative moments calculated by elastic theory at supports of continuous flexural members subject to the following conditions:
The program expects values of redistributed moments respecting all other limits except for the ones on net tensile strain t . For flexural members, the program ensures compliance by suitably restricting the depth of neutral axis.
For slender compression elements, the program expects enhanced values of moments obtained either from a P-Delta analysis or using additional moments as per Section 10.11 of ACI 318-95.
The program does not account for additional capacity of compression elements with helical reinforcement..
Profiles of the most commonly used sections viz. rectangular, flanged and circular can be generated automatically while sections of arbitrary shape may be defined in terms of contour projections as explained later.
You are required to enter the number, diameter and location of bars. Obviously, this data can at best be an intelligent guess. The aim should be to come close to accuracy with minimum of data. For example, while designing a singly reinforced beam you will get the same answer whether a single or several bars are specified parallel to the neutral axis, as long as location of the center of gravity of bars is the same.
It is suggested that data for all sections should include steel in compression as well as tension zones of beams. If the applied bending moment is such that a singly reinforced section would suffice, the program ignores compressive steel. If the section is required to be doubly reinforced, the program calculates the required areas of steel in tension and compression when bars have been so provided.
For column sections, you must supply somewhat more precise data since the calculated area of reinforcement is sensitive to relative bar diameters and their locations. From the compression-bending interaction charts such as those of SP:17A(90) we know that different areas of steel are obtained by varying arrangement of bars.
Minimum steel is obtained by concentrating reinforcement close to the most highly stressed fibers. For example, a wall section subject to axial compression and bending moment is normally reinforced with closely spaced larger diameter bars near the two ends and widely spaced smaller diameter face bars.
On output, areas of longitudinal steel at top and bottom of a section are printed for an element in flexure. If the calculated area of reinforcement is less than the limits imposed by Sections 10.5.1 and 10.5.2, the steel corresponding to the limit preceded by < (less than) symbol is printed.
If a section is required to be doubly reinforced but no bars are provided in compression zone, the program prints the steel corresponding to tension-controlled section preceded by > (greater than) symbol.
The total area of longitudinal steel is printed for members in combined flexure and axial load. If the calculated reinforcement violates either of the minimum and maximum limits viz. <1% and >8% respectively imposed by Section 10.9 the reinforcement corresponding to the limit preceded by an appropriate relational operator ( < or > ) is printed.
The calculated area of longitudinal reinforcement should be distributed amongst various bar groups in approximately the same proportion as that specified in data.
If the factored shear force Vu at a section is more than half of the factored shear strength calculated using Section 11.3.1 the required shear reinforcement is determined by Section 11.5.6.
If the factored torsional moment is more than the value given in Section 11.6.1 then the element is designed for torsion as per Sections 11.6.3.5 and 11.6.3.6.
Section 11.1.1.1 cautions but provides no rules for design when web openings are present. The program therefore does not cater for web openings.
Beams of varying depths are not accounted for by the program. The modified value of shear as suggested in Section 11.1.1.2 should be supplied by the user.
The upper limit as specified in Section 11.1.2 is used for shear strength calculations. The increased values permitted by Section 11.1.2.1 are ignored by the program.
Shear strength of elements under axial compression is enhanced as per Section 11 3.1.2 while shear strength of elements under axial tension is reduced as per Section 11.3.2.3.
The strength calculations for shear as provided in ACI 318-95 are based on semi-empirical rules involving width bw and effective depth d. The program uses breadth of section for bw and overall depth less concrete cover for d. This is strictly correct for rectangular sections. For a non-rectangular section values of breadth and depth of the section should be specified judiciously using specialist literature.
The strength calculations for torsion are more explicit and can be applied to sections of arbitrary shape as well. The program determines the following section properties for torsion calculations:
Acp area enclosed by outside perimeter of concrete cross
section
Ao gross area enclosed by shear flow path = 0.85Aoh
Aoh area enclosed by centerline of the outermost closed
transverse torsional reinforcement
pcp outside perimeter of the concrete cross section
ph perimeter of centerline of outermost closed transverse
torsional reinforcement
t thickness of wall of a hollow section
The program automatically checks if a section is solid or hollow and uses Eq. (11-18) or (11-19) as appropriate taking cognizance of Sections 11.6.3.2 and 11.6.3.3.
The characteristic strength of transverse reinforcement is taken to be the same as that of longitudinal reinforcement. If the two characteristic strengths are different, modify stirrup spacing by a factor equal to the ratio of characteristic strengths of transverse and longitudinal reinforcement.
It is assumed that the outermost closed transverse torsional reinforcement, where required, is located parallel to and at a distance equal to concrete cover from the outside perimeter of concrete cross section.
On output, the ratio Av/s corresponding to each of y and z axes is printed. Here s is the spacing of shear reinforcement along the length of the element and Av is the total area of shear reinforcement within a distance s.
For inclined stirrups or a series of bars bent-up at different cross-sections divide the ratio Av/s by sin(a)+cos(a) where a is the angle between the inclined stirrup or bent-up bar and the axis of the element.
If more than one type of shear steel is provided to reinforce the same portion of the beam, calculate the required strength of shear reinforcement Vs = fyd (Av/s) where fy is the characteristic strength of stirrups and d is the effective depth. The total capacity of various types of shear reinforcement should match or exceed Vs.
If the factored shear force at a section is less than half of factored shear strength no shear reinforcement is required and Av/s is printed as 0.
If the calculated value of Av/s would result in less than minimum shear reinforcement as per Section 11.5.5.3 of ACI 318-95, that value of Av/s which will satisfy the requirement of minimum shear reinforcement is printed preceded by < (less than) symbol. However, you must ensure that the maximum spacing requirements of Section 11.5.4 are not violated.
If the factored shear stress is more than the right hand side of Eq. (11-18) or (11-19) as applicable, the section must be redesigned. This condition is flagged by printing the upper limit of Av/s preceded by > (greater than) operator.
If torsion effects are to be considered as required by Section 11.6.1, the total area of longitudinal reinforcement to resist torsion and the ratio At/s are printed. Here s is the spacing of bars and At is the cross-sectional area of one leg of a closed stirrup.
The minimum value of transverse torsional reinforcement At is taken as half of that required by Section 11.6.5.1. If the calculated value is less than minimum, that value of At/s which will satisfy the requirement of minimum transverse torsional reinforcement is printed preceded by < (less than) symbol. The balance minimum transverse reinforcement to satisfy the requirement of Section 11.6.5.1 is provided by shear reinforcement.
The longitudinal reinforcement for torsion and axial load are combined on output. Other combinations of reinforcement for torsion and those for shear and flexure may be worked out as detailed in Sections 11.3.8 and 11.3.9.
Make sure that the files named ARCI.EXE and ARCI.NTL are available in the current directory or in one of the directories set by PATH command under DOS.
The program is invoked by entering ARCI on console. You are prompted to enter a structure name which may be up to six characters in length. The program appends the default input file extension ".INP" to the structure name and scans directories for the input file. For example, if you type in the structure name as FRAME1, the program searches for a file named FRAME1.INP. If you had created this file earlier, the program takes its contents for data. This is known as batch or off-line mode. On the other hand, if the search for input file fails, the program prompts you for input. This is known as interactive or on-line mode.:
While entering data in either mode, the following conventions apply:
Each of the input modes is described next.
The program enters the interactive mode if input file does not exist. This mode is recommended for processing a small set of data. In the interactive mode, data is entered on console in response to prompts from the program. The prompts are listed below in the order in which they appear followed by an explanation of the expected response.
Specify the force and length units separated by a hyphen. For example, N-MM indicates that the data that follows is in SI units. Consistent units must be used for all data. The valid units are:
Enter an alphanumeric section identifier which may have a maximum of six characters. For each section, the following data up to and including 'Bar Spacing z' must be provided, on completion of which you will be prompted for a new section-id. An underscore (_) as response to section id flags end of section data.
Distance between centers of bars and nearest concrete face
Width of section for bending about y axis.
Overall depth of section for bending about y axis.
Width of section for bending about z axis.
Overall depth of section for bending about z axis.
Effective cover, width and depth are used for shear and torsion calculations as also for checking limits on areas of flexural and shear reinforcement. For some of the standard shapes these values are also used to generate sections automatically if major and minor b and D are as follows:
Major b = Minor D = Breadth of rectangle
Major D = Minor b = Depth of rectangle
Four bars at corners. Origin at intersection of vertical line of symmetry and base
Major b = Breadth of web
Major D = Depth of section
Minor b = Thickness of flange
Minor D = Width of flange
Two bars at bottom. Two bars at top. Origin at intersection of vertical line of symmetry and base
Major b = Minor b = 0
Major D = Minor D = Diameter of circular section
Eight bars. Origin at center of circular section
For shear and torsion calculations, a circular section is treated as a square section of equal area.
If the section is of a standard shape, respond with an underscore to the next prompt to indicate that no contour data is provided and that the section is to be generated automatically.
A polygonal section is defined by a closed contour which is traversed such that concrete is to the left as one advances along the contour. Thus, the outside boundary is traversed anti-clockwise while the boundary of a void is traversed clockwise.
Contour projections Dy and Dz are the y and z components of segments of contour. Being vectors, they have positive or negative values.
Starting point of traversal is the origin of coordinates. Bar locations must be given with respect to this origin.
You are prompted to enter the above pair of data repeatedly till you respond with an underscore to flag end of contour data. At this point, the program checks if the contour is closed or open. The sum of Dy's as also Dz's is zero for a closed contour. An open contour is flagged as a fatal error.
As an example, a 900 x 900 mm square box section with a 300 x 300 mm void and the origin of coordinates located at its lower left corner will be defined by contour projections. Note that for segments 1 to 4 on the external boundary, the traversal is anti-clockwise while for segments 6 to 9 on the void boundary, the traversal is clockwise. The fictitious segment 5 from the external boundary to the void is required because the traversal must be continuous. The fictitious segment 10 nullifies segment 5
The contour projections for this example are tabulated below:
Segment 1 2 3 4 5 6 7 8 9 10 Dy 900 0 -900 0 300 0 300 0 -300 -300 Dz 0 900 0 -900 300 300 0 -300 0 -300
Respond with an underscore to the next prompt to indicate that no bar data is provided and that the bars are to be generated automatically. Note that automatic generation of bars is possible only for sections generated automatically.
Number of bars in a group. Respond with an underscore to flag end of bar data for the section
Diameter of bars in a group. Any reasonable value may be used.
You may specify bars one at a time in which case y and z coordinates of that bar are to be given while bar spacing has no significance. A number of bars at equal spacing may be specified by giving coordinates of the first bar in the group and the spacing of bars along y and z axis. Bar spacing may have a positive or a negative value depending on the direction in which bars are to be generated.
It is permissible to have a non-standard arrangement of bars for a section of standard shape that was generated automatically. The origin of bar coordinates is the same as that of contours.
As an example, section data for a 450 mm square column with an effective cover of 52.5 mm reinforced with 20 bars of 16 mm dia spaced at 69 mm is given below. The concrete section is generated automatically since no contour data is entered. The origin of coordinates is at the intersection of vertical line of symmetry and base. In the table below, the first two rows of bar data refer to the bars on the left and right faces while the last two rows refer to the bars on the bottom and top faces respectively.
| Sec. | Effec | Major | Major | Minor | Minor | Contour | Bar | Bar | Bar Location | Bar Spacing | |||
| Id . | Cover | Width | Depth | Width | Depth | -Dy | Dz- | Nos | Dia | -y- | -z- | -y- | -z- |
| S45 | 52.5 | 450. | 450. | 450. | 450. | _ | 6 | 16. | -172.5 | 52.5 | 0. | 69. | |
| 6 | 16. | 172.5 | 52.5 | 0. | 69. | ||||||||
| 4 | 16. | -103.5 | 52.5 | 69. | 0. | ||||||||
| 4 | 16. | -103.5 | 397.5 | 69. | 0. | ||||||||
| _ | |||||||||||||
An alphanumeric element identifier up to eleven characters long. For each element, the following set of data must be provided, on completion of which you will be prompted for a new element id. An underscore as response to element id flags end of all data.
Select a section, the data for which was entered earlier.
Characteristic compressive strength of concrete.
Characteristic strength of reinforcement.
An alphanumeric load combination identifier up to six characters long. The following data is required for each load combination at the end of which you will be prompted for a new load combination. An underscore in response to this prompt indicates that there are no more load combinations for this station and flags end of data for the station.
An alphanumeric identifier of a location along the element, up to six characters long. While two stations at the ends are usually sufficient for a column, a beam should have at least three stations -- two at the ends and one at midspan.
The following data is required for each station on completion of which you will be prompted for the next station id. An underscore in response to this prompt takes you to the next load combination.
Percentage reduction in moment from its elastic value at a station for a given load combination. As already explained, this data is ignored for an axially loaded element.
Forces and moments at a station for a given load combination.
The program enters the batch mode if input file exists. This mode is recommended for processing a large set of data.
The steps to create a batch mode input file are as follows:
It is important that the underscores marking end of a group of data are not missed. Recall that the items of data requiring termination by an underscore are Section Id, Contour Projection Dy, Bar Numbers, Element Id, Station Id and Load Combination. As a reminder to you, underscores have been placed below these items of data in the blank form.
You may custom design your forms and may also include comments in an input file. Simply enclose the header information or comments within vertical bar characters ( | ). The program ignores all entries between a pair of vertical bars.
A typical batch mode input file is shown below:
|Units| N-mm
|-----------------------------------------------------------------------------|
|Sec Effec Major Major Minor Minor - Contour - Bar Bar Bar Locn Bar spac.|
|Id. Cover Width Depth Width Depth -Dy Dz- Nos Dia y z y z |
|-----------------------------------------------------------------------------|
R1 36. 250. 350. 350. 250. _ _
R2 46. 350. 400. 400. 350. _ 6 16. -129. 46. 51.6 0
6 16. -129. 354. 51.6 0
4 16. -129. 107.6 0 61.6
4 16. 129. 107.6 0 61.6
_
C1 46. 0. 250. 0. 250. _ _
_
|-----------------------------------------------------------------------------|
|Mem Sec Conc Stl -Load- St dM |
|Id. Id. fcu fy -Comb- Id % Pu Vuy Vuz Tu Muy Muz |
|-----------------------------------------------------------------------------|
B11 R1 16. 415. DL E1 0 0 0 -13.E3 4.45E6 2.81E6 0
E2 0 0 0 19.16E3 4.45E6 13.6E6 0
_
DLW1 E1 0 0 0 -11.50E3 9.99E6 2.24E6 0
E2 0 0 0 17.59E3 9.99E6 12.89E6 0
_
DLW2 E1 0 0 0 -12.05E3 2.24E6 2.83E6 0
E2 0 0 0 17.05E3 2.24E6 11.57E6 0
_
_
B12 R1 16. 415. DL 000 0 0 0 -21.91E3 0.96E6 19.07E6 0
1000 0 0 0 -15.73E3 0.96E6 -0.90E6 0
2000 0 0 0 -1.93E3 0.96E6 -9.72E6 0
3000 0 0 0 12.65E3 0.96E6 -3.73E6 0
4000 0 0 0 18.84E3 0.96E6 12.91E6 0
_
_
B18 R1 16. 415. DLW2 000 0 0 0 -77.41E3 -0.15E6 -28.26E6 0
833 0 0 0 -70.94E3 -0.15E6 -41.83E6 0
1667 0 0 0 -52.33E3 -0.15E6 -45.82E6 0
2500 0 0 0 -30.05E3 -0.15E6 -37.40E6 0
3333 0 0 0 52.82E3 0.15E6 2.45E6 0
4167 0 0 0 71.43E3 0.15E6 55.70E6 0
5000 0 0 0 77.90E3 0.15E6 118.53E6 0
_
DLW1 000 0 0 0 -77.41E3 -0.15E6 118.00E6 0
833 0 0 0 -70.94E3 -0.15E6 55.72E6 0
1667 0 0 0 -52.33E3 -0.15E6 2.88E6 0
2500 0 0 0 -30.05E3 -0.15E6 0.01E6 0
3333 0 0 0 52.82E3 0.15E6 -46.56E6 0
4167 0 0 0 71.43E3 0.15E6 -42.16E6 0
5000 0 0 0 77.90E3 0.15E6 -28.19E6 0
_
_
C1 C1 16. 415. DLW BASE 0 -53.4E3 0 0. 0. 2.75E6 31.7E6
_
_
C3 R2 16. 415. DLW BASE 0 -196.3E3 0 0. 0. 3.93E6 144.31E6
_
_
_
Three files are generated by the program.
The first file contains echo of entered data. In the interactive mode, a diskfile is created with the file name and extension as for the input file, e.g. FRAME1.INP. In the batch mode of input, data is echoed on console.
The second file contains graphical data of sections in DXF format. As before, the name of this file matches the structure name but with a default extension of ".DXF". To view sections, load the file using DXFIN command under AUTOCAD or appropriate commands in other software which can import this format. Each section gets drawn on a layer which is named after the section identifier. Initially, all layers are turned on. By turning off all but one layer you may view sections separately. Examples of graphical output may be seen in the section entitled Verification Problems.
The third file contains results of computation. The name of this file is identical to the structure name you entered at the first prompt. The default extension of this file is ".OUT".
The first line of this file identifies the program name, applicable design code, force and length units and page number as shown in the following example:
-------------------------------------------------------------------------------
* CCF:ARCI *** Code:ACI318*** Units:N-mm *** File:FRAME1.OUT *** Page: 1**
-------------------------------------------------------------------------------
The second line is the header of main output as shown below:
-------------------------------------------------------------------------------
Comb Stn As(Long) At/s Avy/s Avz/s As(Top) As(Bot)
-------------------------------------------------------------------------------
where
Comb Load combination identifier
Stn Location along element
As(Long) Total area of longitudinal steel for axial
load, flexure and torsion
At/s Area of one leg of closed stirrup for torsion
divided by spacing
Avy/s Total area of steel for shear along y axis
divided by spacing
Avz/s Total area of steel for shear along z axis
divided by spacing
As(Top) Steel at top of section for flexure
As(Bot) Steel at bottom of section for flexure
For more details regarding calculated steel see relevant sections.
The following header is printed at the beginning of each element output identifying the element, section type, characteristic strength of concrete and yield strength of reinforcement:
-------------------------------------------------------------------------------
*** Element: B11 ***** Type: R1 ***** fck: 16. ***** fy: 415.**
-------------------------------------------------------------------------------
A sample output file is shown on the next page. This file is printer ready. To get a print-out, simply copy this file to device PRN by issuing an appropriate command under DOS.
-------------------------------------------------------------------------------
* CCF:ARCI *** Code:ACI318*** Units:N-mm *** File:FRAME1.OUT *** Page: 1**
-------------------------------------------------------------------------------
Comb Stn As(Long) At/s Avy/s Avz/s As(Top) As(Bot)
-------------------------------------------------------------------------------
*** Element: B11 ***** Type: R1 ***** fck: 16. ***** fy: 415.**
-------------------------------------------------------------------------------
DL E1 <.2132E+03 .1500E+00 .0000E+00 <.0000E+00 <.2610E+03 .0000E+00
DL E2 <.2132E+03 .1500E+00 .0000E+00 <.0000E+00 <.2610E+03 .0000E+00
DLW1 E1 .3070E+03 .3367E+00 .0000E+00 <.0000E+00 <.2610E+03 .0000E+00
DLW1 E2 .3070E+03 .3367E+00 .0000E+00 <.0000E+00 <.2610E+03 .0000E+00
DLW2 E1 <.2192E+03 <.1434E+00 .0000E+00 <.0000E+00 <.2610E+03 .0000E+00
DLW2 E2 <.2192E+03 <.1434E+00 .0000E+00 <.0000E+00 <.2610E+03 .0000E+00
ALL E1 .3070E+03 .3367E+00 .0000E+00 .0000E+00 <.2610E+03 .0000E+00
ALL E2 .3070E+03 .3367E+00 .0000E+00 .0000E+00 <.2610E+03 .0000E+00
-------------------------------------------------------------------------------
*** Element: B12 ***** Type: R1 ***** fck: 16. ***** fy: 415.**
-------------------------------------------------------------------------------
DL 000 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .0000E+00
DL 1000 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 <.2610E+03
DL 2000 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 <.2610E+03
DL 3000 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00 <.2610E+03
DL 4000 .0000E+00 .0000E+00 .0000E+00 .0000E+00 <.2610E+03 .0000E+00
-------------------------------------------------------------------------------
*** Element: B18 ***** Type: R1 ***** fck: 16. ***** fy: 415.**
-------------------------------------------------------------------------------
DLW2 000 .0000E+00 .0000E+00 .0000E+00 .3133E+00 .0000E+00 <.2610E+03
DLW2 833 .0000E+00 .0000E+00 .0000E+00 .2549E+00 .0000E+00 .3860E+03
DLW2 1667 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 .0000E+00 .4260E+03
DLW2 2500 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 .0000E+00 .3413E+03
DLW2 3333 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .0000E+00
DLW2 4167 .0000E+00 .0000E+00 .0000E+00 .2593E+00 .5301E+03 .0000E+00
DLW2 5000 .0000E+00 .0000E+00 .0000E+00 .3178E+00 .1183E+04 .3855E+03
DLW1 000 .0000E+00 .0000E+00 .0000E+00 .3133E+00 .1178E+04 .3802E+03
DLW1 833 .0000E+00 .0000E+00 .0000E+00 .2549E+00 .5304E+03 .0000E+00
DLW1 1667 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .0000E+00
DLW1 2500 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .0000E+00
DLW1 3333 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 .0000E+00 .4337E+03
DLW1 4167 .0000E+00 .0000E+00 .0000E+00 .2593E+00 .0000E+00 .3881E+03
DLW1 5000 .0000E+00 .0000E+00 .0000E+00 .3178E+00 .0000E+00 <.2610E+03
ALL 000 .0000E+00 .0000E+00 .0000E+00 .3133E+00 .1178E+04 .3802E+03
ALL 833 .0000E+00 .0000E+00 .0000E+00 .2549E+00 .5304E+03 .3860E+03
ALL 1667 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .4260E+03
ALL 2500 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .3413E+03
ALL 3333 .0000E+00 .0000E+00 .0000E+00 <.2048E+00 <.2610E+03 .4337E+03
ALL 4167 .0000E+00 .0000E+00 .0000E+00 .2593E+00 .5301E+03 .3881E+03
ALL 5000 .0000E+00 .0000E+00 .0000E+00 .3178E+00 .1183E+04 .3855E+03
-------------------------------------------------------------------------------
*** Element: C1 ***** Type: C1 ***** fck: 16. ***** fy: 415.**
-------------------------------------------------------------------------------
DLW BASE .1576E+04 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00
-------------------------------------------------------------------------------
*** Element: C3 ***** Type: R2 ***** fck: 16. ***** fy: 415.**
-------------------------------------------------------------------------------
DLW BASE .2928E+04 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00
The following examples are taken from Notes on ACI 318-95
Example 1 Rectangular Beam (See Example 10-1 reworked as Example 34-3 of Notes on ACI 318-95).
Determine the main tension reinforcement required for a rectangular beam section with the following data:
Size of beam 10" x
16.8"
Strength of 4000 psi
concrete
Grade of 60
reinforcement
Factored moment 138 kip-ft
The interactive mode session for this example will be as follows:
At the DOS prompt invoke the program by its name
C:>arci
A sign-on message appears followed by a prompt to enter a structure name. Choose any name up to seven characters long, say PCA10-1
Structure Name: PCA10-1
The program looks for a file named PCA10-1.INP and not finding it gets into interactive mode. The prompts and your response should be as follows:
Force-Length Units : lb-in
Section Id : R1017
Effective Cover : 2.5
Major b : 10
Major D : 16.8
Minor b : 16.8
Minor D : 10
Contour Projection : _
Dy
Bar Nos : _
Section Id : _
Element Id : PCA10-1
Section Id : R1017
Concrete fck : 4000
Steel fy : 60000
Load Combination : DL
Station Id : 1/1
Redistribution % : 0
Axial : 0
Shear-y : 0
Shear-z : 0
Torsion : 0
Moment-y : -165600
Moment-z : 0
Station Id : _
Load Combination : _
Element Id : _
The output for this example is shown below:
-------------------------------------------------------------------------------
* CCF:ARCI *** Code:ACI318*** Units:lb-in *** File:PCA10-1.OUT *** Page: 1**
-------------------------------------------------------------------------------
Comb Stn As(Long) At/s Avy/s Avz/s As(Top) As(Bot)
-------------------------------------------------------------------------------
*** Element: PCA10-1 ***** Type: R1017 ***** fck: 4000. ***** fy: 60000.**
-------------------------------------------------------------------------------
DL 1/1 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .1919E+00 .2537E+01
While the first few lines are headers the last line contains results of computation. Under the headings As(Top) and As(Bot) the required steel in square inches are printed in engineering units. The bottom tensile steel compares well with 2.56 sq. in. obtained in Notes on ACI 318-95. The section is required to be doubly reinforced as can easily be ascertained by calculating the moment capacity of concrete alone.
Example 2 Square Column with Uniaxial Bending ( Examples 11-2 &34-5 of Notes on ACI 318-95 )
Determine the reinforcement to be provided in a square column subject to compression and uniaxial bending, with the following data:
Size of column 18 x 18
in.
Strength of 5000 psi
Concrete
Grade of 60
reinforcement
Factored load 53.5 kips
Factored moment 245
ft-kips
This example will be solved in batch mode by creating a file named PCA11-2.INP shown below:
|Units| LB-IN
|-----------------------------------------------------------------------------|
|Sec Effec Major Major Minor Minor - Contour - Bar Bar Bar Locn Bar spac.|
|Id. Cover Width Depth Width Depth -Dx Dy- Nos Dia y z y z |
|-----------------------------------------------------------------------------|
S18 2.5 18. 18. 18. 18. _ 3 1. -6.5 -6.5 6.5 0
3 1. -6.5 6.5 6.5 0
_
_
|-----------------------------------------------------------------------------|
|Mem Sec Conc Stl -Load- St dM |
|Id. Id. fcu fy -Comb- Id % Pu Vuy Vuz Tu Muy Muz|
|-----------------------------------------------------------------------------|
C1 S18 5E3 60E3 DLW 1/1 0 -53.5E3 0 0 0 2940E3 0
_
_
_
Notice that in this example, the section is generated automatically, while bars are generated by entering the relevant data. Output for this example is shown below:
-------------------------------------------------------------------------------
* CCF:ARCI *** Code:ACI318*** Units:LB-IN *** File:PCA11-2.OUT *** Page: 1**
-------------------------------------------------------------------------------
Comb Stn As(Long) At/s Avy/s Avz/s As(Top) As(Bot)
-------------------------------------------------------------------------------
*** Element: C1 ***** Type: S18 ***** fck: 5000. ***** fy: 60000.**
-------------------------------------------------------------------------------
DLW 1/1 .7344E+01 .0000E+00 .0000E+00 .0000E+00 .0000E+00 .0000E+00
Since this element is under axial load and bending moment, the calculated total area of steel is printed under the heading As(Long).
Example 3 Rectangular Beam with Ledge in Torsion (See Example 15-1 of Notes on ACI 318-95)
Determine the reinforcement required for a rectangular beam with ledge given the following data:
Size of the beam 16 x 32
in.
Projection of ledge 6 in.
Thickness of ledge 8 in.
Strength of 5000 psi
concrete
Grade of steel 60
Factored shear 59.8 kips
force
Factored torsional 45.9
moment ft-kips
The batch mode input file for this example is as follows:
|Units| lb-in
|-----------------------------------------------------------------------------|
|Sec Effec Major Major Minor Minor - Contour - Bar Bar Bar Locn Bar spac.|
|Id. Cover Width Depth Width Depth -Dy Dz- Nos Dia y z y z |
|-----------------------------------------------------------------------------|
RL1 1.5 16. 32. 32. 16. 22. 0.
0. 8.
-6. 0.
0. 24.
-16. 0.
0. -32.
_
_
_
|-----------------------------------------------------------------------------|
|Mem Sec Conc Stl -Load- St dM |
|Id. Id. fcu fy -Comb- Id % Pu Vuy Vuz Tu Muy Muz |
|-----------------------------------------------------------------------------|
SB1 RL1 5E3 60E3 DL 1 0 0 0 59.8e3 550.8e3 0 0
_
_
_
The section has been generated here entering the contour data. No details of bars are provided. The program assumes a closed stirrup parallel the outer perimeter of the section. The output for this example is as follows:
-------------------------------------------------------------------------------
* CCF:ARCI *** Code:ACI318*** Units:lb-in *** File:PCA15-1.OUT *** Page: 1**
-------------------------------------------------------------------------------
Comb Stn As(Long) At/s Avy/s
Avz/s As(Top) As(Bot)
-------------------------------------------------------------------------------
*** Element: SB1 ***** Type: RL1 ***** fck: 5000. ***** fy:
60000.**
-------------------------------------------------------------------------------
DL 1 <.1800E+01 .1561E-01 .0000E+00 .2110E-02
.0000E+00 .0000E+00
The longitudinal steel required for torsion is less than 1.8 sq. in., the
minimum for this section. Combined torsion and shear stirrup requirement
is obtained as (At/s)+(Avz/2s) =0.0167 sq. in./in./leg.
The following problems are taken from published literature in order to test the program. All problems pertain to arbitrarily shaped columns.
Verification Problem 1
Type Cross shaped
column
Reference Sinha[1996]
Overall depth and 1000 mm
width
Width of each arm 250 mm
Factored axial 4000 kN
load Pu
Factored moment 1000 kN-m
Muy
Factored moment 1200 kN-m
Muz
Concrete grade M25
Steel grade Fe415
Effective cover 54 mm
Steel from 20706 sq mm
reference
Steel from 19880 sq mm
program
Verification Problem 2
Type Ell shaped
column
Reference Mallikarjun[199
2]
Overall depth and 1000 mm width Width of each leg 500 mm Factored axial 7500 kN load Pu Factored moment -884 kN-m Muy Factored moment 884 kN-m Muz Concrete grade M25 Steel grade Fe415 Effective cover 50 mm Steel from 15000 sq mm reference Steel from 14390 sq mm program
Verification Problem 3
Type Chimney
Reference Pinfold[1975
]
Outer diameter 6710 mm Inner diameter 6290 mm Factored axial 7000 kN load Factored moment 39600 kN-m Muy Factored moment 0 kN-m Muz Concrete grade M30 Steel grade Mild steel Effective cover 105 mm Steel from 29589 sq mm reference Steel from 28270 sq mm program
Errors are classified according to severity as minor, fixable and fatal. The program traps certain errors and reacts in one of the following ways:
The program takes corrective action if a minor error has occurred. A warning is issued by the program as follows:
Non-zero redistribution for column ignored
A non-zero value of moment redistribution for a column is ignored by the program for reasons explained earlier.
Fixable error occurs when an illegal item of data is encountered by the program. The program displays the illegal item of data followed by a question mark and awaits a correction from you.
For example, if you intended to enter an integer number, say 2 but included a decimal point by mistake, the program will pause after displaying
2.?
At this point you may enter the correct value.
If the program is running in batch mode, it is advisable to abort the program by pressing Ctrl+C or Ctrl+Z, make corrections to the input file and rerun.
The program aborts execution if any of the quantitative limitations listed below is exceeded:
Maximum number of section types 99 Maximum number of segments per 99 section type Maximum number of bars per section 99 type Maximum number of stations per 21 element
Other fatal errors are as follows:
Open Contour
Check the segment projections of contours. For a closed contour the sum of projections on y as also on z axis should add up to zero.
Invalid Section ID
A section ID was specified for an element but no corresponding section details were found. It is possible that the section ID was misspelt either in section data or element data.
Exceeding maximum iterations
The solution has failed to converge. This is an exceptional condition. Check your data and if the error persists please inform the vendor of this program.
ACI 318-95 Building Code Requirements for Structural Concrete, American Concrete Institute
Mallikarjuna and P. Mahadevappa [1992] "Computer Aided Analysis of Reinforced Concrete Columns Subjected to Axial Compression and Bending I- L Shaped Sections", Computers & Structures, Vol. 44 No. 5
Ghosh S.K., Fanella D.A. and Rabbat B.G. [1996] "Notes on ACI 318-95", Portland Cement Association
Pinfold, G.M. [1975] "Reinforced Concrete Chimneys and Towers", Viewpoint Publications
Sinha, S.N. [1996] "Design of Cross (+) Section of Column", Indian Concrete Journal, March 1996