Load Path on Rc Building Structures

Notes on Using SAP2000 as a tool, Suyono Nt. 2007 page 1 of 17

Sorry for day i'm on a lazy state in writes all of equations and make details of calculation like areport.

Load Path on RC Building Structures

Because of node limitation in SAP2000 Student version (100 nodes max) onlysmall/moderate numbers of meshing shell elements in my SAP models, it's about 80nodes. For calculation beams bending moment hope it would be satisfied :( ??, foranother purpose of calculating such as slabs moment and/or deflection i'm not sure.In others word it'll not capture the structural behaviour (need more FE mesh).

Material Properties (I left as default, except weight density)

Element dimensions (in mm units)Beams (all beams in X and Y direction)H=400B=200

Column (all columns, below and above storey being considered)H=300B=300

LL½ w l = 0,5*4*3 = 6 kN/mDLslab0,5*0,12*24*3 = 4,32 kN/mDLbeam0,2*0,4*24 = 1,92 kN/m

Load Combination1,2DL+1,6LL

RC beam designModified ACI318-99 parameter to satisfy SNI91 RC building codes.Type: Sway Ordinary (non seismic)

CASE 1Modelling structures with frame element to represent beam and column. Loadsapplied to beam in -z direction, distributed as trapezoidal and triangular.






CASE 2Modelling structures with frame element to represent beam and column, shellelement for slabs to study force distribution on beam members. Here's eccentricitybeing ignore to simplify.






CASE 2Modelling structures with frame element to represent beam and column, shellelement for slabs. Here's eccentricity being considered to study force distributionon beam members. How these take effect on beams internal force. Adjacent nodeshell to beams are connected with rigid link to transfer slab forces.

e=(0,4/2)-(0,12/2)=0,14m




as can be seen, the amount of axial forces are large cause of beam-slab eccentricity.Positive sign (tension) at beam spans and negative sign (compression) at beam end.

It must be converted before to get real moment for RC design purposes.

again :) sorry i'm on lazy state to makes detail of calculation, just do it by yourself.

You can look from researcher who interested in mixed element, truss to beam,beam to shell, shell to solid, etc.




In RC design command i didn't make a further calculation to get design moment,just want to know how much it differ from other models result. Whohah ... it'sabout 35% less than 1st simple models (for a long past years i trusted).

Concluding and Remarks● load from mesh at corners are lost from contribution of beam internal force.● ignoring eccentricity makes plate rotation at end spans are less stiff.● more FE mesh means more accurate result (mesh FE in this model isn't

captures structural behaviour)● make your FE model's simple as possible but not simpler :)

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Load Path on Rc Building Structures