Cross-laminated timber (CLT) is a new generation of engineered wood product developed initially in Europe and has been used in North America for various applications. CLT is composed of at least three layers of lumber boards stacked crosswise in orthogonally alternating orientation to the adjacent layers. CLT has been gaining popularity and increasing application areas in the construction industry, such as building systems, mats for construction and temporary road applications as well as temporary bridges. It is especially identified as the prevailing material in modular construction for the future building industry. However, CLT as a relatively new structural material has limited studies related to their durability and long-term performance. Moreover, nondestructive evaluation methods to understand their mechanical behavior after exposure to harsh environment are lacking. This paper contributes to the development of a rapid nondestructive evaluation method to assess the mechanical properties using transverse vibration method and ultrasonic testing. The free vibration response triggered by the impulse excitation is captured using contact accelerometer and non-contact laser Doppler vibrometer (LDV). The LDV measurement is proven to respond similar to conventional accelerometers but more convenient as a rapid assessment method. While the longitudinal wave speed is measured by ultrasonic testing (UT) in a through-transmission mode, the modulus of elasticity was calculated in terms of measured wave speed. By investigating the different structural states and dimensions of CLT samples, the laboratory and the manufacturing facility, the influences of aging on effective dynamic modulus of elasticity (MOE) and damping are shown. The numerical and experimental results indicate the increase in moisture content decreases the fundamental frequency. Therefore, moisture content should be measured in order to examine the coupled effects of moisture content and aging on the fundamental frequency. The damping ratio extracted using half-power bandwidth method is shown as an additional information related to the moisture content. The non-contact transverse vibration method and UT are shown as an efficient nondestructive evaluation method for assessing the CLT structural state right after the manufacturing as a quality assurance method or after their service in field as a diagnostic tool.

交叉层压木材（CLT）是最初在欧洲开发的新一代工程木产品，已在北美用于各种应用。CLT由至少三层木板组成，这些木板以与相邻层正交交替的方向交叉堆叠。CLT在建筑行业中越来越受欢迎，并不断增加其应用领域，例如建筑系统，建筑用垫和临时道路应用以及临时桥梁。特别被确定为未来建筑行业模块化建筑中的主流材料。但是，CLT作为一种相对较新的结构材料，对其耐久性和长期性能的研究有限。此外，缺乏用于了解暴露于恶劣环境后其机械性能的非破坏性评估方法。本文为快速无损评估方法的发展做出了贡献，该评估方法使用横向振动法和超声测试来评估机械性能。使用接触式加速度计和非接触式激光多普勒振动计（LDV）捕获由脉冲激励触发的自由振动响应。事实证明，LDV测量的响应类似于传统的加速度计，但作为快速评估方法更方便。在通过透射模式下通过超声波测试（UT）测量纵向波速的同时，根据测得的波速计算弹性模量。通过研究CLT样品的不同结构状态和尺寸，在实验室和生产设施中，显示了老化对有效动态弹性模量（MOE）和阻尼的影响。数值和实验结果表明，水分含量的增加降低了基频。因此，应测量水分含量，以检验水分和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。显示了老化对有效动态弹性模量（MOE）和阻尼的影响。数值和实验结果表明，水分含量的增加降低了基频。因此，应测量水分含量，以检验水分和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。显示了老化对有效动态弹性模量（MOE）和阻尼的影响。数值和实验结果表明，水分含量的增加降低了基频。因此，应测量水分含量，以检验水分和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。数值和实验结果表明，水分含量的增加降低了基频。因此，应测量水分含量，以检验水分和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。数值和实验结果表明，水分含量的增加降低了基频。因此，应测量水分含量，以检验水分含量和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。应当测量水分含量，以检查水分含量和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。应当测量水分含量，以检查水分含量和老化对基频的耦合影响。使用半功率带宽方法提取的阻尼比显示为与水分含量有关的附加信息。非接触式横向振动方法和UT被显示为一种有效的非破坏性评估方法，用于在制造后立即将其作为质量保证方法或在其作为诊断工具投入现场使用后评估CLT结构状态。