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（河北工業(yè)大學(xué)土木與交通學(xué)院， 天津 300401）
［摘要］植筋混凝土梁在達(dá)到規(guī)定的植筋深度時，經(jīng)循環(huán)荷載作用后植筋端頭處截面因抗剪能力不足出現(xiàn)斜裂縫，引起構(gòu)件脆性破壞。針對此問題，提出了一種優(yōu)化設(shè)計(jì)方案，即在植筋端頭處設(shè)置箍筋。設(shè)計(jì)6組試件，對比優(yōu)化前后植筋梁的破壞特征、延性系數(shù)、承載力、鋼筋應(yīng)變和疲勞損傷的差異。結(jié)果表明：在設(shè)計(jì)時將植筋端頭置于原構(gòu)件箍筋處能夠明顯提高植筋混凝土梁的延性系數(shù)和承載力，降低疲勞損傷。植筋深度決定了植筋梁的破壞特征，植筋深度小于20d，經(jīng)優(yōu)化后的試件仍發(fā)生脆性破壞。錨固深度達(dá)到25d時，經(jīng)優(yōu)化的試件疲勞破壞特征由脆性破壞轉(zhuǎn)為塑性破壞。推導(dǎo)出了與植筋深度和混凝土殘余應(yīng)變相關(guān)的疲勞損傷計(jì)算公式，經(jīng)優(yōu)化設(shè)計(jì)后試件的疲勞損傷可以降低13-93%～19-24%。
［關(guān)鍵詞］植筋； 疲勞損傷； 優(yōu)化設(shè)計(jì)； 延性系數(shù)
中圖分類號：TU375文獻(xiàn)標(biāo)識碼：A文章編號：1002-848X(2018)09-0092-05
Experimental research on optimal design of rebar-planting concrete beam under cyclic load
Liang Linxiao, Yan Xikang, Pang Yusong, Wen Guoqiang
(School of Civil and Transportation Engineering, Hebei University of Technology, Tianjin 300401, China)
Abstract:Brittle failure may occur on rebar-planting concrete beam under cyclic load because of shear crack near the end of rebar-planting section even if rebar-planting concrete beam fulfills requirement of rebar-planting depth. A structural optimization measure was put forward to set stirrup at the end of rebar-planting section. Six groups of rebar-planting concrete beams were analyzed through experiments. Parameters before and after optimal design were contrasted, including failure mode, ductility coefficient, ultimate loads, strain of post-installed rebar and fatigue damage. Results show that setting stirrup at end of rebar-planting section can improve the ultimate bearing capacity and deformability effectively and reduce fatigue damage. The failure mode of the rebar-planting beam mainly depends on the planted depth. With the rebar-planting diameter less than 20d, the brittle fracture occurs for the optimized specimen. With the rebar-planting diameter more than 25d, the fatigue failure mode of the optimized specimen changed from brittle failure to ductile failure. A formula for calculating the fatigue damage related to the planted depth and the concrete residual strain was deduced. It is shown that the fatigue damage of the specimen can be reduced by 13-93%～19-24% after the optimal design.
Keywords:rebar\|planting; fatigue damage; optimal design; ductility coefficient
*河北省建設(shè)科學(xué)技術(shù)研究計(jì)劃（2014-124）。
通訊作者：閻西康，博士，教授，博士生導(dǎo)師，Email:tjsyxk@163.com。
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