Development of NDE Technologies for Post Earthquake Damage Assessment of Jacketed Bridge Columns

采用钢或纤维增强聚合物（FRP）复合护套改造桥梁柱的结构性能得到了很好的证明，在美国和日本，确实有大量的公路桥梁柱采用了这种护套进行改造。然而，被护套覆盖的柱受到地震破坏，从而使其不可见，从而大大削弱了柱的强度。为了解决这个问题。该项目将开发无损评估技术，特别是电磁和超声成像技术，并通过实验研究这些技术在评估用钢或玻璃钢包覆的钢筋混凝土柱地震后损伤方面的有效性。考虑的损害包括分层裂缝、混凝土与钢筋之间的剥离、混凝土柱与护套之间的剥离。本研究的主要任务包括：(1)开发电磁和超声成像样机；(2)进一步开发电磁和超声成像样机的图像重建算法；(3)在实验室对不同程度损伤的钢和FRP夹套桥柱进行样机测试，验证电磁和超声成像技术。(4)通过对钢或frp护套桥柱进行现场测试，验证电磁和超声成像技术。PI目前正在指导一项由联邦公路管理局（FHWA）、加州交通部（Caltrans）和材料与工艺工程进步协会（SAMPE）资助的实验测试项目，在该项目中，27根用不同FRP夹套包裹的半比例桥柱在单次和双次弯曲配置下的循环荷载下进行测试和损坏。该程序提供了一个极好的机会来验证所提出的技术在检测柱的损伤和粘结界面中的空洞方面的有效性，而不需要为建造和损坏这些柱而提出项目的成本。为了促进更紧密的合作和促进教育效益，研究生将在PWRI度过两个夏天，在日本进行联合实验，而PWRI的一名初级研究工程师将在UCI度过一个夏天，参加涉及Caltrans桥梁的实地实验。该项目还将使本科生获得跨学科和合作研究的经验。这是CMS-INT计划NSF 98-36“美日城市地震减灾合作研究”第一轮（1998财年）竞赛下的一个奖项。＊＊＊

9812585 Feng The enhanced structural performance of bridge columns retrofitted by steel or fiber-reinforced polymer (FRP) composite jackets has been well demonstrated and a large number of highway bridge columns have indeed been retrofitted with such jackets in the United States and Japan. However, seismic damage of the columns covered by the jackets and thus made invisible can considerably weaken the columns. In order to solve this problem. this project will develop nondestructive evaluation (NDE) techniques, particularly electromagnetic (EM) and ultrasonic imaging technologies, and experimentally investigate their effectiveness for assessing post-earthquake damage of reinforced concrete columns wrapped with steel or FRP jackets. Under consideration are damages such as delamination cracks, debonding between concrete and reinforcing rebars, delamination between concrete columns and jackets. The primary tasks of this research include (1) development of prototype EM and ultrasonic imaging devices, (2) further development of the image reconstruction algorithms for both EM and ultrasonic devices, (3) verification of the EM and ultrasonic imaging technologies by testing the prototypes on steel-and FRP- jacketed bridge columns damaged to different levels in laboratory, and (4) verification of the EM and ultrasonic imaging technologies by field testing on steel- or FRP-jacketed bridge columns. The PI is currently directing an experimental testing program funded by the Federal Highway Administration (FHWA), the California Department of Transportation (Caltrans), and the Society for the Advancement of material and Process Engineering (SAMPE), where twenty-seven half-scale bridge columns wrapped with different FRP jackets are tested and damaged under cyclic loads in both single and double bending configurations. This program provides and excellent opportunity to verify the effectiveness of the proposed technologies in detecting damage in the columns and voi ds in the bonding interfaces, with no cost to the proposed project for building and damaging these columns. To facilitate closer collaboration and promote educational benefit, graduate students will be selected to spend two summers at PWRI to conduct joint experiments in Japan, while one junior research engineer from PWRI will spend one summer at UCI to participate in the field experiment involving Caltrans bridges. This project will also expose undergraduate students to interdisciplinary and collaborative research experience. This is an award under the first round (FY'98) competition of the CMS-INT initiative NSF 98-36 "US-Japan Cooperative Research in Urban Earthquake Disaster Mitigation". ***