huangyhg

mortar cracks that continue through blocks
we have an exterior wall made of three layers of bricks facing east. on the outside is a 4鈥?face brick, in the middle is a 4鈥?common brick, and on the inside is a 4鈥?structural glazed tile. the building was constructed a few decades ago and they used large w-sections for the columns. the columns are placed every 21鈥?and they are between the common brick and the structural glazed tile. the problem we have is that there are cracks in the mortar along the north and south sides of the columns. the interesting thing is that the cracks is down a vertical mortar line and does not jog over to the next mortar line when it hits one of the tiles. instead it breaks the tiles in half and matches back up with the same mortar line on the other side of the tile.
the question we have is what could be causing the tiles to be cracking? we figure if it is the wall pulling away from the column it would follow the mortar lines, but since it does not we are wondering what kind of forces could be applied to the column to shear the tiles in half. the tiles are 4鈥滺x4鈥滵x8鈥滾 and they are hollow making them about 1鈥?thick. the beams above the columns are composite sections of concrete and w-sections. if anyone has any suggestions of what we could look into or if any more information is needed. please let me know.
thank you all for your time.
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i agree with hoolie that it is a differential movement problem. when masonry cracks through the section without following the mortar joints, it is a result of overstress, not just shrinkage. in this case, either your columns or your wall have settled slightly, one relative to the other. this causes shear stress in the structural tile or any other masonry attached to the column. keep in mind that it only requires a very small amount of strain to cause these cracks over short distances in masonry.
isolation is the solution.

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