Electromagnetic testing is the most widely used technique for the inspection of steel wire ropes. As one of the electromagnetic detecting approaches, the magnetic flux leakage (MFL) method has the best effect for the detection of broken wires. However, existing sensors based on MFL method still have some problems. (1) The size of the permanent magnet exciter is usually designed according to experience or rough calculation, and there is not enough depth analysis for its excitation performance; (2) Since the detectable angular range for a single Hall component is limited, Hall sensor arrays are often employed in the design of MFL sensors, which will increase the complexity of the subsequent signal processing due to the extensive use of Hall components; (3) Although the new magneto-resistance sensor has higher sensitivity, it is difficult to be applied in practice because of the requirement of the micron-level lift-off. To solve these problems, a sensor for the detection of broken wires of steel wire ropes based on the principle of magnetic concentration is developed. A circumferential multi-circuit permanent magnet exciter (CMPME) is employed to magnetize the wire rope to saturation. The traditional Hall sensor array is replaced by a magnetic concentrator to collect MFL. The structural parameters of the CMPME are optimized and the performance of the magnetic concentrator is analyzed by the finite element method. Finally, the effectiveness of the designed sensor is verified by wire breaking experiment. 1–5 external broken wires, handcrafted on the wire rope with a diameter of 24 mm, can be clearly identified, which shows great potential for the inspection of steel wire ropes.

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A new structural system c alled a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as the Wenchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical for engineering practice.

Damage detection tests of inclined cables, steel pipes, spherical shells, and an actual cable-stayed bridge were conducted based on the proposed musical tone law method. The results show that the musical tone law method could be used in the damage detection of isotropic material structures with simple shape, like cables, pipes, plates, and shells. Having distinct spectral lines like a comb with a certain interval distribution rule is the main characteristic of the music tone law. Damage detection baseline could be established by quantizing the fitting relationship between modal orders and the corresponding frequency values. The main advantage of this method is that it could be used in the structural damage detection without vibration information of an intact structure as a reference.