I agree with Mr. Remmetter that the IBC specifies minimum seismic forces for the design of the walls' out-of-plane anchorage to diaphragms. However, out-of-plane anchorage of tilt-up walls to diaphragms is the most important structural component of a tilt-up building exposed to major earthquake hazard, as is true for much of California.

Tilt-up buildings first became popular in California after World War II. Their popularity is in part due to the fact that they are relatively economical to construct. In addition, an ability to accommodate attractive designs and historically minimal maintenance requirements add to the attractiveness of tilt-up wall panels. Tilt-ups received their name based on how they are constructed. The tiltup wall panels are cast on the concrete floor slab and then tilted into place after curing. The panelized wood roof (Figure 1) is assembled in large, premanufactured panels that are lifted into place with a crane. It is the use of these two different construction materials, and the lack of adequate connections to tie them together, that has led to poor performance of tiltups in past earthquakes.

In this article, one structural engineering firm discusses an ongoing challenge they face when working on addition and renovation projects… the difficulty in determining information about existing reinforcing in concrete and masonry structures. Engineers from Steve Schaefer and Associates, Cincinnati, Ohio, took it upon themselves to perform an evaluation of the features, capabilities and comparative costs of several rebar locators. The following article is an overview of their experience.