engleski

Traditional column connections with iron dowels - experimental and numerical analysis

Permanent problems with stone columns in Croatia motivated us on comprehensive research. Retrofit of columns, being noted for centuries and existing distinct fractures concentrated around connections with capitals and bases point to some fundamental deficiency of the structural system. Traditional connections consist of carefully smoothed contact areas joined only with centrally placed iron dowel what makes them very sensitive to any disturbance from vertical position. Analyses show that even a small imperfection in the construction process, temperature changes and especially eccentric loads result in the leaning of the contact to one side. Described contacts do not have sufficient rotational stiffness to compensate rotations. Eventually, high edge stresses cause numerous fractures. Performed laboratory tests pointed out additional problem of irregularities of contact areas, which, together with eccentric load, became critical for all specimens. Tests were carried out on almost real scale samples from traditional quarries. Testing procedure ensured separate analyses to centric and eccentric loading with respect to actual stress distribution in structures. All abovementioned assertions were confirmed with a range of numerical models: from simple frame and shell models to complex solid models. All models were calibrated with results of the laboratory tests. This work shows that it is essential to understand real nature of connections behaviour if we want to approximate real stress distributions, positions of thrust lines and finally safety factor in order to form adequate retrofit strategies.

Laboratory tests; Numerical analysis; Stone column; Capital; Base; Iron dowel; Rotational stiffness; Contact stress; Eccentric load; Irregularities of contacts areas; Fracture propagation

nije evidentirano