Effective stiffness of infills

[tlen]

Hello-
I am looking into the retrofit of a 1950's concrete frame building with masonry infill walls. The masonry appears to have minimal reinforcing. ICO 2003 for existing buildings requires the calculation of the effective stiffnes of the infill. (A509.2.1.2) Any suggestions on how to calculate this? In addition, the code requires the determination of the effect of the infill's stiffness on the rest of the frame.

Suggested readings?

Thanks for any direction!
tlen

 

[miecz]

Tall Building Structures Analysis and Design, by Bryan Stafford Smith and Alex Coull has a chapter devoted to the analysis and design of masonry infill.