R. POPESCU (1), G. POPESCU (2), A.M. DINCA (3)
(1) Research & Design Diplomat Eng. Ist Degree, Technical Inspector in Designing A1, A3, E
(2) Research & Design Diplomat Eng. Ist Degree, Technical Expert A, Inspector in Designing A1, A3
(3) Design Diplomat Engineer, Master in building structure
Seismic assessment of masonry buildings is important in high seismic risk areas such as Romania. This is because, unreinforced masonry shear walls subjected to in-plane seismic loading and eccentric compression, usually fail by diagonal cracking due to principal tensile stresses.
The masonry sections of the Romanian Codes, generally conform to Eurocode 6 and Eurocode 8, but additional provisions regarding the calculation of shear strength capacity to resist lateral in-plane action from earthquake forces exist. For example, in the design of unreinforced masonry walls empirical coefficients are used to reduce the design shear strength capacity (VRd).
With these provisions included, the number of storeys which can be designed in masonry buildings is significantly reduced and as a result it is may be necessary to sometimes alter the architectural layout in order to fulfil the strength requirements.
An alternative design methodology , however, exists in Romania which, it is believed, more closely represents the real behaviour of masonry structures to seismic actions. Using this method the formulas for shear strength capacity (VRd) are evaluated taking into account the failure of the unreinforced masonry by diagonal cracking, in accordance with the Theory of Strength of Materials ; moreover, the methodology is based on numerous research studies and laboratory tests undertaken over 20 years. The method has been used by engineers to evaluate the performance of new and old masonry building structures.
In the first part of this paper a short theoretical presentation of the methodologies is given followed in the second part by a case study in which three buildings with the same structural arrangement in plan but with different numbers of storeys (one, two and three) are analysed. The response of the whole structure to seismic action is evaluated using structural software . In addition the shear strength capacities of the walls are calculated using software , and manually after the Romanian code. Finally, the shear strength capacities, calculated using the two methodologies are compared.