NEESR-CR: An Innovative Seismic Performance Enhancement Technique for Steel Building Beam-Column Connections

NEESR-CR：一种创新的钢结构梁柱连接抗震性能增强技术

• 批准号: 0936547
• 负责人: Tasnim Hassan
• 金额: $ 59.04万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0936547&HistoricalAwards=false
• 关键词: NEESR; CR; Innovative; Seismic; Performance

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes the North Carolina State University (NCSU, lead institution) and the University of North Carolina at Pembroke (UNCP, subaward). This project will utilize the NEES equipment site at the University of Minnesota to experimentally validate an innovative technique for enhancing the seismic performance of steel building beam-column connections.Intellectual Merit: The proposed seismic enhancement technique involves heat treating sections of beam flanges by exposing these sections to a very high temperature for certain amount of time before slow air cooling. Such a heat treatment process reduces the strength of steel in the heat treated areas of the flange. Consequently, under seismic loading, a plastic hinge develops at the heat treated beam section (HBS). A connection enhanced by this technique will have the advantages of the popular reduced beam section (RBS) connection, but the HBS will have better energy dissipation than the RBS connection. In RBS connections, "weakening" of the beam flanges induces a plastic hinge away from the welds. In HBS connections, a plastic hinge develops at the heat treated section because of the reduced strength of steel. Moreover, as the beam flange remains intact and the inelastic modulus of steel is not altered at the HBS, the lateral and torsional buckling resistances of the HBS connection will be higher than those of the RBS connection. Consequently, the HBS connection will dissipate a larger amount of energy with a minimum loss of strength or stiffness compare to the RBS connection. Through a pilot study at NCSU, the seismic performance enhancement technique is validated analytically. This project will validate the technique by conducting full-scale connection experiments. Currently, RBS is the most popular connection design because of its seismic performance and cost effectiveness. The HBS connection is anticipated to be more seismically robust and economical than the RBS connection. The research will be performed through integrated experimental and analytical studies. Material experiments of heat treated and unconditioned coupons will be conducted and data will be analyzed to quantify the influence of heat treatment parameters (peak temperature and hold time) on the reduction of strength and to determine the constitutive model parameters. Detailed structural analyses of HBS connections will be performed to determine the optimum heat treatment parameters and geometry of HBS. Beam-column connections with and without HBS will be built and tested to demonstrate seismic performance enhancement of the modified connections. Detailed measurement of strains, displacements and rotations at various locations will be recorded for investigating both the local and global failure modes of HBS connections. Experimental and analytical results will be used to refine the technique and to develop a methodology for practical application of the technique.Broader Impacts: The research results will be integrated into professional development courses, and the research will involve faculty and students from a predominantly undergraduate Native American institution in the experimental activities. A methodology for application of the novel technique will be developed and disseminated. The heat treatment concept is applicable to steel building or bridge connections; the proposed heat treatment technique will benefit industries that use welded joints. Experimental data from this project will be archived and made available to the public through the NEES data repository.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该奖项是NSF 09-524项目招标“小乔治·e·布朗地震工程模拟（NEES）研究网络（NEESR）”竞赛的结果，包括北卡罗莱纳州立大学（NCSU，牵头机构）和北卡罗来纳大学彭布罗克分校（UNCP，子奖项）。该项目将利用明尼苏达大学的NEES设备现场，通过实验验证一种创新技术，以提高钢结构建筑梁柱连接的抗震性能。知识优势：提出的地震增强技术包括在缓慢空气冷却之前将梁法兰部分暴露在非常高的温度下一定时间的热处理。这种热处理工艺降低了法兰热处理区域钢的强度。因此，在地震荷载作用下，在热处理梁段（HBS）处形成塑性铰。通过这种技术增强的连接将具有流行的减束截面（RBS）连接的优点，但HBS连接将比RBS连接具有更好的能量耗散。在RBS连接中，梁法兰的“弱化”导致塑料铰链远离焊缝。在HBS连接中，由于钢的强度降低，在热处理部分形成塑性铰链。此外，由于梁缘在HBS处保持完整，且钢的非弹性模量没有改变，因此HBS连接的抗侧屈曲和抗扭屈曲能力将高于RBS连接。因此，与RBS连接相比，HBS连接将以最小的强度或刚度损失消耗更大的能量。通过NCSU的试点研究，分析验证了抗震性能增强技术的有效性。该项目将通过进行全尺寸连接实验来验证该技术。目前，RBS是最受欢迎的连接设计，因为它具有抗震性能和成本效益。预计HBS连接比RBS连接在抗震性能上更强，也更经济。该研究将通过综合实验和分析研究进行。进行热处理和无条件试样的材料实验，并对数据进行分析，量化热处理参数（峰值温度和保温时间）对强度折减的影响，确定本构模型参数。将对HBS连接件进行详细的结构分析，以确定最佳热处理参数和HBS的几何形状。将建立和测试带有和不带有HBS的梁柱连接，以证明修改后的连接的抗震性能增强。为了研究HBS连接的局部和全局失效模式，将记录不同位置的应变、位移和旋转的详细测量。实验和分析结果将用于改进该技术，并为该技术的实际应用开发一种方法。更广泛的影响：研究结果将整合到专业发展课程中，并且研究将涉及来自主要是美国原住民机构的本科生的教师和学生。将发展和传播一种应用新技术的方法。热处理概念适用于钢结构建筑或桥梁连接；提出的热处理技术将使使用焊接接头的工业受益。该项目的实验数据将存档，并通过NEES数据存储库向公众提供。

项目成果

Seismic Enhancement of Welded Unreinforced Flange-Bolted Web Steel Moment Connections

• DOI: 10.1061/(asce)st.1943-541x.0001575
• 发表时间: 2016-11
• 期刊: Journal of Structural Engineering-asce
• 作者: Machel Morrison;Doug Q. Schweizer;T. Hassan

Resilient welded steel moment connections by enhanced beam buckling resistance

• DOI: 10.1016/j.jcsr.2016.07.012
• 发表时间: 2016-12
• 期刊: Journal of Constructional Steel Research
• 影响因子: 4.1
• 作者: Machel Morrison;T. Hassan