Study On Torsional Response And Torsional Control Index Applicability Of Slope Frame Structure

Slope structure means a structure is built on a slope in the mountainous region. During design computation of the slope structure, the displacement ratio (especially the storey drift displacement ratio) usually goes beyond the code limit value, which means the structure has large eccentricity and the torsional response is obvious, but it is easy for the period ratio to meet the code limit value, even sometimes far less than the code limit value, which means the structure has enough torsional stiffness and the torsional response is weak, there is a contradiction between the two indices. Usually designer tries his best to adjust the layout of the structure to limit the eccentricity, but it is still hard for the displacement ratio to meet the code limit. So designers are usually puzzled: Is the torsional response of slope structure obvious? Can the torsional control indices be applied to the slope structure? By far, research on the slope structure is limited, so it is urgently required to study the torsional response of slope structure and the applicability of code torsional control indices to slope structure. This paper has systematically studied the torsional response of a single-storey slope structure and the relationship between torsional control indices, as well as the applicability of code torsional control indices to slope structure. A lot of multi-storey frame structure models of dropped floors are designed to verify the correctness of theory analysis and check the applicability of code torsional control indices to this kind of structures.The main conclusions are summarized as the following:①The torsional response of slope structure is obvious, when the number of one side dropped spans is less than the0.6times of the number of the total spans,with the increase of dropped spans and floors, the torsional response of slope structure become more obvious, however, with the increase of floors above the up located floor, the torsional response of slope structure become less obvious.②From the laws of elastic torsional response of a single-storey structure, found that the " peak value" phenomenon of torsional response may happen once the uncoupled period ratio Tθ/Ty is during Tθ/Ty=0.9～1.0. So in order to avoid the "peak value", should limit the uncoupled period ratio Tθ/Ty to a more strict value, such as:(Tθ/Ty≤0.8).(3) The coupled period ratio Tθ’/Ty’ by code can’t be applied to slope structure,so suggest to cancel the limitation of coupled period ratio Tθ’/Ty’. ④The storey drift displacement ratio by code can’t be applied to slopestructure,so suggest to cancel the limitation of storey drift displacement ratio.