纤维增强复合材料筋混凝土受弯构件裂缝宽度计算

Crack Width Formulas for Flexural Concrete Members Reinforced with Fiber-Reinforced Polymer Bars

摘要:

为评估和校准现行规范中纤维增强复合材料（fiber-reinforced polymer， FRP）筋混凝土受弯构件裂缝宽度计算公式，系统收集了国内外FRP筋混凝土（FRP-RC）受弯构件裂缝宽度试验数据。基于若干筛选原则，建立了包含111根FRP-RC受弯构件的数据库。通过对比最大裂缝宽度试验值和计算值，评估了国内外3部常用规范的适用性。结果表明，规范GB 50608—2010严重低估了裂缝宽度，尤其低估了GFRP-RC和BFRP-RC构件的裂缝宽度；相比之下，规范CJJ/T 280—2018能较准确地预测裂缝宽度，而规范ACI 440.1R-15高估了裂缝宽度。基于该数据库，通过引入弹性模量比E_f / E_s修正了规范GB 50608—2010中的裂缝间纵向受拉筋应变不均匀系数ψ，并分别校准了3部设计规范中的FRP筋表面形态黏结特性系数。

关键词:纤维增强复合材料筋;混凝土受弯构件;裂缝宽度;数据库;校准

Abstract:

To evaluate and calibrate the maximum crack width formulas for flexural concrete members reinforced with fiber-reinforced polymer （FRP） bars in current design standards， available literature on crack width tests of FRP reinforced concrete （RC） flexural members was extensively surveyed. After applying multiple filtering criteria， a database including 111 FRP-RC flexural members was developed. Then， the database was used to evaluate the accuracy of the crack width provisions from three design guidelines by comparing the tested widths with predictions. It was determined that GB 50608—2010 highly underestimated the maximum crack width， especially for the GFRP-RC and BFRP-RC members. In contrast， CJJ/T 280—2018 was more predictive than the other guidelines， while ACI 440.1R-15 provided conservative predictions. Based on this database， modifications were made to the non-uniform strain coefficient formula for tensile FRP bars in GB 50608—2010 by introducing an elastic modulus ratio E_f /E_s. Furthermore， the bond-dependent coefficients in the three design guidelines were calibrated to account for the effect of surface treatment.

Key words:fiber-reinforced polymer (FRP) bar;flexural concrete member;crack width;experimental database;calibration