Joints in cold-formed steel framing structures are usually designed as bolted lap type ones with a gusset plate. Unlike the end-plate joints in hot-rolled structures, the load in such joints is transferred through shearing of the bolts and bearing of the material. The prediction of their structural properties may be problematic in viewof unfavourable influence of the hole clearance and hole ovalization resulting from low bearing resistance of thin walls. A few experimental programmes showed that these issues lead to a different behaviour of the whole joint comparing to common end plate type. These concerns may be particularly important for joints under variable loading, which are prone to deterioration of structural properties. The testing programme conducted by the authors was focused on their behaviour under monotonic and cyclic loading with attention to a potential drop of resistance and stiffness. Monotonic tests revealed quite similar course of the joints’ response. In view of high deformability of the specimens at the intermediate stage of each monotonic test, plastic moment resistances of joints were associated with the initial part of the moment-rotation curves and were multiple times lower than maximum moments obtained in the experiments. The quantities of deterioration of structural properties were determined based on cyclic tests. Drop of resistance and stiffness was observed for several levels of loading range, but the trend of decrease varied for each property. Application of the DIC technique allowed one to identify qualitatively and quantitatively the sources of joint deformability.

In this paper we investigate the quantitative importance of efficiency wages of no-shirking type in explaining business cycle fluctuations in Bulgarian labor markets. This is done by augmenting a relatively standard real business cycle model with unobservable workers effort by employers and efficiency wage contracts, as well as through the inclusion of a detailed government sector. This imperfection in labor markets introduces a strong internal transmission mechanism that allows the model framework to capture the business cycles in Bulgarian data better than earlier models, and setups assuming perfectly-competitive labor markets in particular.