Testing RPC's Compressive Strength On Cast-in-place Pull-out Method By Monte Carlo Simulation

Reactive powder concrete is a new type of ultra high strength cement-based composite material.It has been widely used by engineers in the world since its invention because of its excellent performance.Compared with ordinary concrete,the compressive strength of RPC can be configured from 100 MPa to 800 MPa which is much higher than the ordinary high-strength.At the same time,RPC has many advantages,such as good toughness,corrosion resistance,high temperature resistance and light weight.Although RPC has been invented more than 20 years,its filed test methods are very few.There are only two ways including reserving cube compression blocks and the core drilling method.The core drilling method has too much damage to the structure while reserving cube compression blocks can't guarantee the test block and structure in the same curing condition,therefore they are limited.This text selects cast-in-place pull-out method which is a non-destructive testing technology to carry out the test and explores its feasibility.Compared with the post-install pull-out method,the cast-in-place pull-out method has higher accuracy,and the later test is easy to operate,which is more suitable for field testing.In order to pursue accuracy,pull-out test usually chooses the measuring points which far away from the reinforcement area in the past.However in some practical projects,the reinforcements in component are very concentrated,so we can't escape this situation.Therefore,the author selects the ultra high strength reinforced RPC column as the test object.Consider the feasibility of the cast-in-place pull-out method to detect the compressive strength of RPC and the influence of the longitudinal reinforcement spacing.This experiment's components are divided into 3 strength grades: RPC120,RPC150,and RPC180.Each strength grade level consists of 4 RPC columns installed with longitudinal reinforcements and stirrups and 1 plain RPC column without steers which contain a corresponding number of test cubes.All components have the same stirrup spacing.A circle bracing device was used in this experiment.Then,use the least square method to fit the experimental data and do regression analysis to calculate corresponding strength formula.Then,the strength formula is deal with accuracy analysis ? significant test ? confidence interval estimate and fitting line modified.Text results have indicated that there is significant liner correlation betweenthe pull-out force and the compressive strength of reinforced RPC columns,and the accuracy of the strength formula is very high.The pull-out force of the reinforced RPC column is greater than the plain RPC column when the longitudinal reinforcement spacing is less than 50 mm.But when the longitudinal reinforcement spacing is more than 75 mm,the pull-out force of them is the same.After using the least square method to establish the fitting line of the compressive strength and the pull-out force of RPC specimens with different longitudinal reinforcement spacing,this paper takes the reinforcement distance as another independent variable,and uses Monte Carlo method to simulate the three factors fitting formula of pulling out force?reinforcing bar spacing and pull-out force.Compared with the predicted value calculated by fitting formula and the test measurement value,we can calculate its relative error.The results show that the three factor fitting formula's fitting effect is good,and the error between them is small.The fitting formula can be used to predict the compressive strength of the reinforced RPC specimen.