The Measurement of the Local Slip in Bamboo-Reinforced Concrete Beams Using Moment-Curvature and Bond-Stress

This paper presents a method of measuring local slip in bamboo-reinforced concrete beams.Local slips(so)are calculated by reducing the elongation of the bamboo reinforcement(ebo)with the elongation of the concrete(eco).The elongation of bamboo reinforcement(ebo)is determined in two ways,namely,read directly through a straingauge mounted on the bamboo reinforcement and calculated based on the force analysis or curvature moment as a control.The elongation of the concrete(eco)is calculated using force analysis or curvature moment.The process of calculating curvature moments and bond stress employs the Excel program.The steps in calculating the elongation of concrete(eco)consist of calculating the curvature moment,calculating the bond-stress at the initial crack,and calculating the bond-stress at the second crack until the beam collapses.Further,the results of the calculation of the elongation of the concrete(eco)and the elongation of the bamboo reinforcement(ebo)resulting from the reading of the strain-gauge are substituted in the local slip calculation equation.The results of the calculation analysis show that the local slip is approaching the local slip resulting from the experiment.The relationship behavior of bond-stress vs.slip indicates conformity with the experimental results.The local slip calculation based on the moment-curvature can be considered as control of the experiment result.

Influence of Confined Concrete Models on the Seismic Response of RC Frames

In this study, the influence of confined concrete models on the response of reinforced concrete structures is investigatedat member and global system levels. The commonly encountered concrete models such as Modified Kent-Park, Saatçioğlu-Razvi, and Mander are considered. Two moment-resisting frames designed according to thepre-modern code are taken into consideration to reflect the example of an RC moment-resisting frame in thecurrent building stock. The building is in an earthquake-prone zone located on Z3 Soil Type. The inelasticresponse of the building frame is modelled by considering the plastic hinges formed on each beam and columnelement for different concrete classes and stirrups spacings. The models are subjected to non-linear static analyses.The differences between confined concrete models are comparatively investigated at both reinforced concretemember and system levels. Based on the results of the comparative analysis, it is revealed that the column behaviouris mostly influenced by the choice of model, due to axial loads and confinement effects, while the beams areless affected, and also it is observed that the differences exhibited in the moment-curvature response of columncross-sections do not significantly affect the overall behaviour of the global system. This highlights the critical roleof model selection relative to the concrete strength and stirrup spacing of the member.

A comparative study of the ATC-40 recommended and numerically derived M-φ relationship

Nonlinear static analysis procedures are key tools in evaluating the performance of existing buildings and verifying the design of seismic retrofits in seismically active regions. In this procedure, nonlinear force-displacement or moment-curvature （M-φ） behavior needs to be defined. In the ATC-40 document, values of M-φ have been proposed to model elements in a nonlinear procedure. However, these values need to be investigated to determine if they are representative of actual values. In this paper, an attempt has been made to numerically derive M-φ curves to simulate actual performance. Then, these curves are compared with the ATC-40 recommended curves with respect to various parameters. The study indicated that ATC-40 suggested values are conservative in nature in most situations.

Multistage seismic damage constitutive model and parameter calibration of reinforced concrete columns

The road traffic network contains a large number of bridges,and calculating bridge damage using refined models demands significant time and resources.Therefore,developing a rapid evaluation method for the seismic capacity of regular bridges has become a crucial scientific challenge.This study presents an approach in which the ductile column is represented by a single degree-of-freedom model with elastic-plastic constitutive characteristics.Utilizing an uncoupled multivariate power function model and a plastic hinge model,a multidimensional power function model for section hierarchical curvature is constructed.Subsequently,the seismic multistage damage constitutive model(SMSD-CM)of member hierarchy is deduced and calibrated through theoretical methods.This model efficiently derives the trilinear constitutive model of components by inputting several crucial parameters.The SMSD-CM accurately simulates the hysteretic curve and displacement time-history under actual seismic conditions and aligns well with pushover analysis results from tests.The efficiency,ease of operation,and accuracy make the model suitable for rapid evaluation of the seismic capacity of regular bridges within the road traffic network.