The Mechanical Properties Of New Type Of Bamboo Reinforced Concrete Columns Subjected To Eccentric Loads

Steel reinforced concrete has been widely used in civil engineering field because of its excellent mechanical properties.However,a large amount of non-renewable resources is consumed due to the excessive using of steel,and all kinds of waste generated from the production process of steel seriously pollute the environment.As a result,many scholars have been trying to search out more economical and environmental alternative materials to substitute the steel in concrete construction.Bamboo stands out from the numerous potential materials for its favorable tensile strength and rapid regeneration characteristic.Much research has been done on the mechanical properties of concrete slabs and beams reinforced with bamboo strips,but little has been known about the feasibility of using bamboo in concrete column,especially when columns subjected to eccentric loads.Hence,this paper would investigate the behavior of bamboo reinforced concrete columns under eccentric compression loads by experimental studies and theoretical analysis.The main work of this paper contains the following aspects:(1)The strength test is carried out to determine the mechanical strength of bamboo and composite bamboo-cable.The results show that compared with bamboo,the composite bamboo-cable has higher tensile and compressive strength,and the discrete coefficient of strength is obviously reduced,at the same time,the elastic modulus has also significantly increased.(2)In order to improve the bonding strength between bamboo and concrete,several modification methods are proposed and then the pullout test is conducted.The results show that when bamboo surface is coated with epoxy and attached with sands,the bamboo reinforced concrete exhibits the best bonding performance,which increases the bonding strength between bamboo and concrete up to several times comparing to untreated one.(3)Experimental research is conducted to investigate the difference between short columns reinforced by untreated bamboo,treated bamboo,composite bamboo-cable and steel.The results show that compared with steel reinforced concrete column,bamboo reinforced concrete columns exhibit larger crack width and smaller depth of the compression zone when the column cracking;but when compared with untreated bamboo reinforced concrete column,concrete columns reinforced with treated bamboo or composite bamboo-cable have more cracks but with smaller crack width at the failure stage.(4)To overcome the disadvantages of insufficient cross-section stifness and brittle failure of bamboo reinforced concrete column,steel-bamboo reinforced concrete column is proposed and carried out on experimental study by changing the area ratio between steel and bamboo.The results show that it can significantly reduce the consumption of steel,but also has most of the mechanical characteristics of steel reinforced concrete column,so as to overcome the shortcomings of bamboo reinforced concrete member.(5)Based on the assumption about cooperative work between bamboo and concrete,the formulae for load-bearing capacity of bamboo reinforced columns are deduced.The calculation results show good agreement with experimental results so that the formulae can be used for reference in the engineering practice.