Crack assessment is an essential process in bridge detection. In general, most non-contact crack detection techniques are not suitable for widespread use. The reason for this is that they all need to position the ruler at the inspection site in advance or calibrate the camera unit pixel size at a certain distance in a very intricate process. However, the object distance method in this paper can complete the calculation using only the crack image and the working distance, which are provided by an acquisition system equipped with a camera and laser range finder. First, the object distance method and the scale method are compared by calculating the crack width, and the results show that the object distance method is the more accurate method. Then, a double edge pixel statistical method is proposed to calculate the crack length, which solves the problem of redundant and missing pixels. In addition, the conventional mosaic algorithm is improved to realize an image mosaic for the more efficient splicing of crack images. Finally, a series of laboratory tests were conducted to verify the proposed approach. The experiments showed that the precision of crack length extraction can reach 92%, and the improved algorithm stitching precision can reach 98%.

In reinforced concrete (RC) frame-shear wall structure, the coupling beam needs to yield before the wall limbs are damaged, in order to dissipate the energy of the external load. However, the coupling beam has a limited energy dissipation capacity. Once severely damaged, the coupling beam is difficult to be repaired, which hinders the structural recovery after an earthquake. Considering excellence of metal rubber (MR) in hysteresis energy dissipation and deformation self-reset, this paper changes the energy dissipation mode of the coupling beam by adding an MR damper to the beam. Firstly, the stress-strain curve of MR was obtained through mechanical experiments, and used to construct the constitutive model of the material. Then, the parameters of the damper were designed based on the constitutive model. Next, the MR dampers were installed on the coupling beams of a 12-layer RC frame-shear wall structure. The authors analyzed the time histories of the elastoplastic dynamics of the structure under seismic actions, and calculated the seismic responses like interlayer displacement, absolute acceleration, and base shear force. These parameters were compared with those of the structure without the damper, and the output-deformation envelope curve of the damper on each layer were obtained. In this way, the authors studied how the parameters of the MR damper affect the seismic response of RC frame-shear wall structure. The results show that adding the MR damper to coupling beam can effectively weaken the seismic response of the RC frame-shear wall structure.

The seismic load can bring serious damages to the coupling beams and frame beams in the frame-shear wall structure. Such damages can hardly be repaired, causing functional loss to the structure. One of the best ways to consume seismic energy input, rationalize the damage mode of structure, and prevent serious damages to the main components is to install metal rubber (MR) dampers materials in the frame-shear wall structure. Based on Park and Ang’s damage model, this paper presents pertinent formulas of damage indexes, and uses them to quantify the failure mode. Then, the correspondence was established between damage level of the target structure, reasonable damage mode, and damage index. Finally, two ABAQUS models of an 18-floor frame-shear wall structure were constructed: an uncontrolled structure (traditional frame-shear wall structure) and a controlled structure (frame-shear wall structure with MR dampers). Through comparative analysis, the characteristic parameters of the damper were determined for the reasonable damage mode, and the failure mechanism of the target structure was identified accurately under seismic load.

The wind characteristics of the atmospheric boundary layer in forested regions exhibit a significant complexity due to rugged terrain, seasonal climate variability, and seasonal growth of vegetation, which play a key role not only in designing optimal blades to gain better performance but also in assessing the structural response, and there is a paucity of research on such wind fields. Therefore, this paper investigates wind characteristics via on-site wind field measurement. The mean and fluctuating wind characteristics of the forested region in different seasons were analyzed based on the field measurement data. The results show that for the mean wind characteristics, the seasonally fitted exponents play a decisive role in characterizing the mean wind profile, while the season and temperature are the key factors affecting the mean wind direction in forested regions. For fluctuating wind characteristics, the seasonal power-law function can accurately characterize the turbulence intensity profile. Moreover, the ratio of the three turbulence intensity components is significantly affected by temperature and season, and the Von Kármán spectrum has better applicability in the cold and less canopy-disturbed winter than in the other three seasons. The proposed seasonally fitted parameters show better applicability in terms of vertical coherence.

To figure out the performance of dampers made of metal rubber (MR) that are installed in bridge and frame shear wall structures to change the energy consumption mode of artifacts, experiments were performed on the MR material processed by improved processing techniques to test its compression and shear hysteresis properties in high-temperature environment, and discover the laws of the impact of factors such as the improved processing techniques and temperature on the compression and shear hysteresis of the material. At the same time, based on test curves and the strain hardening laws of the material, this paper employed the least square method to perform piecewise linear fitting on MR curves, and the corresponding strain hardening constitutive model was established and verified. The study suggests that, after processed by the improved processing techniques, the compression and shear hysteresis energy consumption performance of the MR test pieces is very stable, and the shear strength had been improved. As the temperature increases, the metal rubber consumes more vibrational energy, and the stiffness of MR vibration isolator increases as well; at a same temperature, as the strain amplitude and relative density increase, the vibrational energy consumed by the MR damping material increases accordingly. The simplified constitutive model constructed in the paper has a simple form, it can not only describe the strain hardening features of the material, but also conform to the test curves, therefore, it can facilitate the parameter design and the calculation of MR dampers. The research conclusions obtained in this paper can provide theoretical and experimental evidence for the processing, preparation, and application of MR dampers, and it is of very important theoretical significance and practical value.