Study On Bond-slip Properties Of Micro-expansion Inorganic Polymer Concrete Filled Steel Tube

Inorganic polymer concrete filled steel tube (Inorganic Polymer Concrete FilledSteel Tubes (IPCFST)) is a combination of new materials, its core concrete has rapidhardening early strength, energy saving and low power consumption Superiority,With the steel combination, the ferrule’s role of external steel increases the stability ofthe core concrete, and improves its mechanical properties under pressure, while thepipe is used as a template of construction, which improves the efficiency ofconstruction. The role of bond-slip between steel and core concrete is the foundationof both working together, currently, home and abroad have done a lot of research onthe interfacial bonding properties of ordinary concrete filled steel tube, and achievedcertain results. For this new material composite member of inorganic polymerconcrete filled steel tube, studying the interfacial bond-slip performance is necessary,and easy to understand the mechanism of both work together. In this paper, expansivecontent is changing parameters, a six specimens of IPCFST are produced, through thepush-out test, the article studies interfacial bond-slip properties of IPCFST specimensunder the different expansive content, its main results are as follows:(1) Based on the push-out test, the strain’s curves on the pipe surface of eachspecimen along the longitudinal direction of the pipe are obtained, after analysis, itcan obtain that steel strain-location curve is exponential distribution curve, andaccording to the adhesion force of concrete-filled steel tube interface is proportionalto the pipe stress’s differential, it can obtain that bond strain’s curves are alsoexponential distribution;(2) Based on the push-out test, the paper obtains Launched load-slip (F-S) curveof each specimen, and analyze and summarize the characteristic of curve. Byanalyzing the F-S curve, it obtains ultimate bond load, ultimate slip value and averagebond strength values, comparative analysis of the results under different expansivecontent, it finds that: interfacial adhesion of IPCFST specimen was graduallyincreasing with content increasing of expansion agent, interfacial bond strength of thespecimens with4%and6%expansion agent content relative to the specimens with0%expansion agent content are increased by48.6%and137.9%.(3) Through the push-out test of inorganic polymer concrete filled steel tube and the push-out test of ordinary concrete filled steel tube which have been done by thegroup to do, the paper obtain expansion agent and material impact the bond strengthof inorganic polymer concrete filled steel tube:①Interfacial bond strength ofconcrete filled steel tube increase with the increase of the expansion agent content;②under the conditions of the same expansion agent content, interfacial bond strengthof inorganic polymer concrete filled steel tube are smaller than the ordinary concretefilled steel tube’s.(4) By finite element analysis, the paper simulates interfacial bond strength ofconcrete-filled steel tube using COMBIN39nonlinear spring element, obtains that thecalculated results and experimental results are coincident. ultimate bond load’smaximum relative error obtained by the finite element and experiment is0.063, itsmaximum relative error of limit slip is0.163, which illustrates the results of finiteelement simulation is effective, interfacial bond strength of concrete filled steel tubeusing finite element simulation is viable.