that given by the Hudson equation for two different stability coefficients. 

 The strength portion of the design envelope is plotted for two different con- 

 crete tensile rupture strengths, f y = 600 psi and f y = 900 psi . It can be 

 seen that the increase in waist ratio from 0.33 to 0.38 has only a minor 

 effect on the stability but increases the acceptable weight by 63 percent for 

 600-psi concrete and 46 percent for 900-psi concrete. It is also evident from 

 Figure 12 that stress changes more rapidly with weight for lighter dolosse 

 than for heavier dolosse and that wave height has only a minor effect on the 

 combined static and pulsating design stress. 



Application of Design Methods to Existing Polos Structures 



96. Table 5 shows design data for dolos structures throughout the 

 world as given in Zwamborn, Bosnian, and Moes (1980), and Markle and Davidson 

 (1983) . In these tables ABR is the location abbreviation used in the 

 following figures, H is the design wave height, T the design wave period, 

 d the toe water depth, cot (a) the structure slope, and PLACE is the placement 

 as follows : 



MBT, MBH, MBHT - Main breakwater trunk, head, and head and trunk, 



respectively 



SBT, SBH - Secondary breakwater trunk and head, respectively 



In Table 5, r is the waist ratio, phi is the placement density, S is the 

 specific gravity, STRN is the concrete compressive strength, num is the 

 number placed, and reinf is the structural reinforcement used. 



97. Table 6 shows the results of applying the dolos structural design 

 procedure to these structures. The stresses shown are combined static and 

 pulsating design tensile stress levels for a probability of exceedance of 



2 percent. In Table 6, W is the dolos weight and STRN = f y is the rupture 

 tensile strength computed using the compressive strength, f' c , in the formula 



fy = 200 + 0.09 fc (29) 



98. Figure 11, showing stress versus dolos weight for various Hudson 

 equation stability coefficients, also plots most of the structures listed in 

 Table 6. It can be seen from this figure that most of the structures through- 

 out the world have design stress levels between 400 and 1,000 psi without 

 impacts . 



44 



