Scaffolding is equipment usually used at construction sites. A scaffolding structure is lightweight and made of elements used many times. The characteristics of scaffolding make it susceptible to dynamic actions present at the structure or occurring nearby. A scaffolding structure of medium size was subjected to analysis in this paper. The structure FEM model was loaded with single force harmonic excitation with various frequencies ranging from 1 Hz to 12 Hz applied in one of many selected points on the scaffolding façade. In the first step, natural frequencies and mode shapes of the analyzed structure were calculated. Then the full dynamic analysis was carried out to obtain maximum displacements of selected control points. The relation of excitation force frequency and location to the amplitudes of generated displacement was observed. It was found that low excitation frequencies close to the natural frequencies of the structure produced vibrations ranging to large areas of the scaffolding surface. Higher excitation frequencies are usually less propagated at the scaffolding but still may produce some discomfort to the structure users in the vicinity of the excitation force location. Scaffolding is equipment usually used at construction sites. A scaffolding structure is lightweight and made of elements used many times. The characteristics of scaffolding make it susceptible to dynamic actions present at the structure or occurring nearby. A scaffolding structure of medium size was subjected to analysis in this paper. The structure FEM model was loaded with single force harmonic excitation with various frequencies ranging from 1 Hz to 12 Hz applied in one of many selected points on the scaffolding façade. In the first step, natural frequencies and mode shapes of the analyzed structure were calculated. Then the full dynamic analysis was carried out to obtain maximum displacements of selected control points. The relation of excitation force frequency and location to the amplitudes of generated displacement was observed. It was found that low excitation frequencies close to the natural frequencies of the structure produced vibrations ranging to large areas of the scaffolding surface. Higher excitation frequencies are usually less propagated at the scaffolding but still may produce some discomfort to the structure users in the vicinity of the excitation force location.

The parametric anti-resonance phenomenon as an active damping tool for suppression of externally excited resonant vibration is numerically studied herein. It is well known fact that the anti-resonance phenomenon, i.e. the stiffness periodic variation by subtractive, combination resonance frequency, brings stabilization and cancelling into self-excited vibrations. But this paper aims at a new possibility of its application, namely a damping of externally excited resonant vibration. For estimation of its effect we come both from a characteristic exponent of the analytical solution and numerical solution of forced vibration of 2DOF linear system with additional parametric excitation. The amplitude suppression owing to the parametric anti-resonance is studied on several parameters of the system: a depth of parametric excitation, mass ratio, damping coefficient and small frequency deviations from the parametric anti-resonance.

Considering the low accuracy and low efficiency of the traditional calibration method for base strain sensitivity of accelerometers, a novel base strain sensitivity calibration system with steady harmonic excitation is proposed. The required cantilever beam for calibration is driven by an electromagnetic exciter to generate a base strain varying in a steady harmonic pattern. By applying a Wheatstone bridge circuit, the generated strain with low distortion can be measured. The measurement system with a compensation function can automatically calibrate the base strain sensitivity. The amplitude linearity and frequency response characteristics of the base strain sensitivity in two accelerometers are obtained experimentally, and the uncertainty in the results is 2% ( k = 2).