can carry no tension, and an intermediate value for partially effective members. A tension 

 effectiveness is also assigned to the plates, which in addition may be used to account for 

 cutouts such as hatches in the deck; see footnote on page 52. 



"Effectiveness" can also be used if more than one material has been used in the 

 construction. The effectiveness is taken as the product of the above number times the modu- 

 lus ratio. The modulus ratio is the actual modulus of the material divided by a reference 

 value of the modulus. 



Density 



Structural mass is calculated as the product of the volume and density of the structural 

 element. If more than one material is used, a density factor, which is the ratio of the actual 

 density to the reference density, is associated with each element. For sections made of one 

 material, all density factors will be 1.0. 



Plate Shear Factor (PG) 



A plate shear factor (similar to the tension effectiveness) is needed for each plate. 

 As with tension effectiveness, there are two factors, one due to inability to carry shear and 

 the other due to shear modulus. Plates which end at a nearby cross section should have a 

 low effectiveness, and plates with a modulus greater than the reference value should have 

 an increased effectiveness. PG must never be 0. If the plate has no shear effectiveness, it 

 is not considered as a structural element. 



Mass Items* 



If mass calculations are to be made, additional information is needed for each non- 

 structural mass. Nonstructural mass includes machinery, cargo, fuel, virtual mass, etc. For 

 each item, the weight (W), location of its center of gravity (YW, ZW), and moments of inertia 

 about its own center of gravity (WYY, WYZ, WZZ) are required. Here WYY is the moment of 

 inertia about an axis through the center of gravity of the item and parallel to the z-axis. The 

 YY indicates that the integral which gives the moment of inertia has the factor Y^. 



Other Numbers 



A count of the total number of nodes (NN), plates (NP), and masses (NW) is needed. 

 If masses are to be computed, the length of the section (DX) and the basic material density 

 (RHO) are needed. 



*See pages 59 and 60. 



