Projects and Solutions

Lateral load paths in a brick-veneered wood frame house

Typical wood-frame residential houses have a brick veneer attached to the studs of the wood-frame walls by flexible brick ties. The veneer serves as an aesthetic feature and prevents the ingress of rain water, but is not designed to carry lateral load. To understand the lateral load paths in a brick-veneered wood-frame house, the contribution of the brick veneer to lateral load transmission has been investigated using field tests on a full-scale two-storey house and complimentary computer models. Once a validated computer model is constructed, it can also be modified to analyse lateral load paths in other wood-frame houses.

Objectives:
(1) To conduct field tests to quantify the transfer of lateral load from the wood-frame to the brick veneer in a residential house.
(2) To validate computer models which serve as analytical tools to investigate lateral load paths in wood-frame houses

Tests were conducted on the full-scale house at the Insurance Research Laboratory for Better Homes. The wood-frame floor diaphragm was pulled without loading the brick veneer and the reactions under the wood-frame walls were measured by the load cells. The figure below shows the location and direction of the applied load in each test. Load was applied at the Upper (U) and Lower (L) floors in the West (W) and South (S) directions. For example, test US refers to a test where the upper floor diaphragm was pulled towards south. The table below shows the mean of the load carried by the wood frame and the brick veneer, expressed as the percentage of total applied load. The brick veneer does carry a significant fraction of the total lateral load, particularly for loads applied to the upper floor.

Tests and results

At present, the computer model can predict the test results very well, except for the test UW, as indicated by the Test-to-Predicted (T/P) ratios shown in the table below. Further improvement of the model is necessary. This model also predicts that up to 90% of the lateral load on the roof may be resisted by the brick veneer, instead of being carried by the wood-frame structure.

Computer model

Although the brick veneer is not designed to carry any lateral load, the field tests show that it does carry a significant amount. The computer models also suggest that the major load path from the loaded roof to the ground passes through the brick veneer.


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Updated June 22, 2010 by contactWE
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