Research On Deformation Limits Of I-Section RC Shear Walls Based On Material Strain

Performance-based earthquake design marks the future development of seismic design, as it is capable to evaluate and control the structure’s damage state and potential repair cost. The key step of this design method is to attain the quantified performance criteria which describe the extent to which a structure is damaged. Shear walls are the main lateral resistant systems of high-rise buildings. The I-section walls are among the most commonly used, core tube or intersection of walls in two orthogonal directions could form an I-shape cross section. Given the fact that flanged walls possess considerable difference in mechanical characteristics, deformation capability and failure modes from rectangular walls, it is thus necessary to gain insight into the deformation criteria of the I-section RC shear walls. The research mainly includes:(1) Verify the rationality of the FE models and the parameters of the Concrete Damaged Plasticity model. With reference to the literature, the rationality of the FE model’s element type, element sizes, constraints and loading method is elaborated, the CDP’s parameters such as dilation angle and viscosity are discussed, reliability is guaranteed via comparing analytical results with several test specimens.(2) A total of 324 I-section RC shear walls are designed with representative varying parameters which include shear-span ratio, axial load ratio, ratio of longitudinal reinforcement in boundary elements, ratio of horizontal and vertical reinforcement in the web and ratio of confinement reinforcement in boundary elements. It is found that the shear-span ratio and moment-shear ratio are the two dominant factors over the failure modes of shear walls. Based on the two parameters, the classification standard of failure modes is established, correction based on 53 test specimens is carried out and the accuracy is much improved..(3) With reference to the Chinese codes and latest research, 7 performance ranges and 6 performance limits are put forward, the standard of defining these limits is proposed based on the correlation between material strain and damage state and repairability, residual strength ratio of the force-displacement curve is also considered. Deformation criteria of all models are attained according to the standard. Parameter analysis was carried out to study the influence of different factors over the load-displacement curves and deformation criteria. It is found that axial load ratio and moment-shear ratio are the two dominant factors in the flexure and flexure-shear failure modes while shear-span ratio have greater influence over shear failure.(4) Based on failure modes, axial load ratio and moment-shear ratio, statistical study is carried out to attain deformation criteria of 6 performance levels(2 levels in shear failure), the criteria are then corrected with reference to the data of 16 test specimens with improved rationality.