Seismic performance of circular reinforced concrete columns subjected to compression, bending and torsion with low and moderate shear span ratio

Under the action of an earthquake, the piers of urban curved bridges are usually subjected to compression, bending and torsion due to the geometric irregularity and with low and moderate shear-span ratio. To explore the seismic performance of piers under combined actions, this paper made a theoretical analysis on the seismic performance of four circular RC columns under combined action with low and moderate shear-span ratio through experimental research. Taking the shear-span ratio and torsion-bending ratio as the main variables, cyclic bending loading and combined cyclic bending and torsion loading were carried out on the columns, respectively. The results showed that the increase of torsional effect and shear effect will increase the failure height of the piers and weaken the energy dissipation capacity and bearing capacity. Through the extraction of characteristic points in the test data, the relationship between force, displacement and torsion-bending ratio of columns with shear-span ratio below 4 was fitted. The bending and shear restoring force models of columns with spiral stirrups and small torsion-bending ratio were established. Moreover, based on the variable angle truss theory, the concrete improvement coefficient β was introduced, and the formula of torsional bearing capacity of columns under combined actions with low and moderate shear-span ratio was deduced. Compared with the test data, when the value of β was taken as 1.1, the proposed formula could be well applied to the calculation of bearing capacity of piers with torsion-bending ratio below 0.2 under combined actions with low and moderate shear-span ratio.

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Opracowanie rekordu ze środków MEiN, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2022-2023)