Masonry coefficient of friction

[mapeddie]

I am reveiwing the lateral force demand on an existing unreinforced masonry brick wall. I am looking for the allowable shear stress for a masonry brick wall and the coefficient of friction of masonry on masonry?

 

[Ussuri]

I think the co-efficient of friction for masonry on masonry is about 0.60-0.70.

 

[MotorCity]

I'm not sure if the code allows it, but I would not consider friction to resist any lateral forces. I would only consider the allowable shear stress of the block and mortar.

 

[JAE]

I agree with MotorCity

 

[bkal]

British masonry code BS5628-1, Cl. 21.1.1 gives indication (0.6) of friction by enhancing a charactersitic initial shear strength by 0.6*design vertical load. The code also gives a coefficient of friction between clean concrete and masonry faces as 0.6, Cl. 22. (Note that the material factor for shear is 2.5 in this code, and there are other limits on the value of total shear strength).

I would also be careful in claiming it.

 

[mapeddie]

Thank you all for your help.

 

[henri2]

In addition to two other requirements, MSJC Code sec 2.2.5.2 (c)states in-plane shear stresses in URM designed by ASD shall not exceed v + 0.45 Nv/An. The commentary indicates the 0.45 is the coefficient of friction (increased from 0.2)..and offers references which delves into this matter.

BTW, seems to me that the foregoing applies to new construction and not existing URM..which brings me to code provisions for dealing with existing URM.

LA City had developed a program which became codified and designated as Division 88 (Earthquake Hazard Reduction in Existing Buildings)in the LA Building Code. Div 88 had provisions for URM buildings and many other jurisdictions in CA later adopted similar regulations. It is my understanding that Div 88 has been

For URM walls utilized to carry vertical and sesimic loads, under Division 88, in-place shear tests or core tests were required to ascertain the shear strength. These results were then taken into account in the lateral analysis.

Have you considered testing to determine shear?