Data Requirements

Each run of RCSlab obtains the following data in any consistent set of units from the GSA analysis or RCSlab design data as appropriate:

Symbol	Definition
$N_{xx}$	ultimate applied axial force per unit width in the x-direction
$N_{yy}$	ultimate applied axial force per unit width in the y-direction
$M_{xx}$	ultimate applied bending moment per unit width about the x-axis
$M_{yy}$	ultimate applied bending moment per unit width about the y-axis
$N_{xy}$	ultimate applied in-plane shear force per unit width
$M_{xy}$	ultimate applied torsion moment per unit width
$e_{add}$	additional eccentricity $\left( e_{add} > 0 \right)$–considered as acting in both senses
$e_{\min}$	minimum eccentricity $\left( e_{\min} \right)$– considered as acting in both senses
$h$	section thickness $(h > 0)$
$z_{t1}$	position of top reinforcement centroid in direction 1 $\left( 0 < z_{t1} < \frac{h}{2} \right)$
$z_{t2}$	position of top reinforcement centroid in direction 2 $\left( 0 < z_{t2} < \frac{h}{2} \right)$
$z_{b1}$	position of bottom reinforcement centroid in direction 1$\left( \frac{- h}{2} < z_{b1} < 0 \right)$
$z_{b2}$	position of bottom reinforcement centroid in direction 2 $\left( \frac{- h}{2} < z_{b2} < 0 \right)$
$\theta_{1}$	angle of reinforcement in direction 1, anticlockwise with respect to x-axis
$\theta_{2}$	angle of reinforcement in direction 2, anticlockwise with respect to x-axis
$A_{st1,min}$	minimum top reinforcement to be provided in direction 1 $\left( 0 < A_{st1,min} \right)$
$A_{st2,min}$	minimum top reinforcement to be provided in direction 2 $\left( 0 < A_{st2,min} \right)$
$A_{sb1,min}$	minimum bottom reinforcement to be provided in direction 1 $\left( 0 < A_{sb1,min} \right)$
$A_{sb2,min}$	minimum bottom reinforcement to be provided in direction 2 $\left( 0 < A_{sb2,min}\right)$
$f_{cd}$	compressive design strength of concrete $\left( f_{cd} > 0 \right)$
$f_{cd,t}$	compressive design strength of top layer of concrete $\left( f_{cd} > 0 \right)$
$f_{cd,b}$	compressive design strength of bottom layer of concrete $\left( f_{cd} > 0 \right)$
$f_{cdc}$	cracked compressive design strength of concrete $\left( f_{cdc} > 0 \right)$
$f_{cdu}$	uncracked compressive design strength of concrete $\left( f_{cdu} > 0 \right)$
$f_{cdt}$	tensile design strength of concrete $\left( f_{cdt} > 0 \right)$
$\varepsilon_{trans}$	compressive plateau concrete strain $\left( \varepsilon_{trans} \geq 0 \right)$
$\varepsilon_{cax}$	maximum axial compressive concrete strain $\left( \varepsilon_{cax} \geq \varepsilon_{ctrans} \right)$
$\varepsilon_{cu}$	maximum flexural compressive concrete strain $\left( \varepsilon_{cu} \geq \varepsilon_{cax} \right)$
$\beta$	proportion of depth to neutral axis over which rectangular stress block acts $(\beta \leq 1)$
$\left( \frac{x}{d} \right)_{\max}$	maximum value of x/d, the ratio of neutral axis to effective depth, for flexure: ${\left( \frac{x}{d} \right)_{\min} < \left( \frac{x}{d} \right)_{\max} < \frac{0.5}{\left\lbrack \beta\left( 0.5 + \min\frac{\left\{ z_{t1},z_{t2}, - z_{b1}, - z_{b2} \right\}}{h} \right) \right\rbrack}}$
$E_{s}$	elastic modulus of reinforcement
$f_{yd}$	design strength of reinforcement in tension$\left( f_{yd} > 0 \right)$
$f_{ydc}$	design strength of reinforcement in compression,$\left( f_{ydc} > 0 \right)$
$f_{\lim}$	maximum linear steel stress of reinforcement$\left( f_{\lim}>0 \right)$
$\varepsilon_{plas}$	yield strain of reinforcement in tension $\left( \varepsilon_{plas} > 0 \right)$
$\varepsilon_{plasc}$	yield strain of reinforcement in compression $\left( \varepsilon_{plasc} > 0 \right)$
$\varepsilon_{su}$	design value of maximum strain in reinforcement
$\varphi_{\Delta}$	maximum permitted angle between applied and resulting principal stress

In addition, the program needs to know whether to use, where appropriate, the faster approach and, if so, what the maximum area of reinforcement so calculated should be before the rigorous approach is used.

Within RCSlab the reinforcement positions are measured with respect to the mid-height of the section, the positions being measured positively upwards. The reinforcement angles are specified with respect to the x-axis and measured positively in an anticlockwise direction looking from above. It should be noted that the concrete is assumed to have zero tensile strength in the analysis; the tensile strength, $f_{cdt}$, is only used to calculate the compressive strength when tensile strains are present.

The results of each run consist of the required area of reinforcement, negative if tensile, in each direction in the top and bottom faces or an error flag indicating that a solution could not be found.