Wind load is one of the main factors of plastic greenhouse collapse. To solve the dynamic response problem of greenhouses under wind load and determine the dangerous section of a skeleton structure, the investigated lump method is presented for the dynamic response analysis of a plastic greenhouse, considering pulsating wind on the basis of Timoshenko beam theory. First, the investigated lump is designed according to the Timoshenko beam microbody concept. On the basis of Timoshenko beam theory, the governing equations of the skeleton structure of the greenhouse are derived, and the realization process of the algorithm is also provided. Second, the accuracy and effectiveness of the proposed numerical method are verified by an example in which the bending wave of a variable cross section beam with free ends propagates. Finally, the dynamic response of the steel skeletons of plastic greenhouses is analyzed under the effect of the simulation wind speed, and the spatial distribution of the maximum node displacement and the section maximum stress of the steel skeleton are obtained. Computational results show that the displacement peak is near the top of the plastic greenhouse. The most dangerous section of the top chord in the steel skeleton is near the leeward bottom, which has a maximum stress of 219.4 MPa, and the most dangerous section of the bottom chord is near the 1 m height on the leeward side of the plastic greenhouse, which has a maximum stress of 248.5 MPa. Bending stress is the main factor of the rapid increase of stress at the bottom of the skeleton. The maximum node displacement and cross-sectional stress caused by fluctuating wind loads are higher than those caused by average wind loads. The fluctuating wind load should be considered in the wind-induced response analyses of plastic greenhouses.

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A numerical algorithm is presented to analyze earthquake response of tall reinforced concrete (RC) chimneys based on stick multidegree-of-freedom models. The algorithm considers the eccentricity phenomena between spatial discrete nodes and corresponding centroids of investigated lumps. The spatial discrete segments of the chimney are used to construct the investigated lumps. The equations of dynamic equilibrium of the investigated lumps are derived, and the numerical calculation procedure is implemented. Phenomena of eccentricity are studied for 150 m and 210 m RC chimneys. Seismic stresses and effects of vertical ground motion for the two chimneys are also studied. Numerical results show that the tensile and compressive stresses of the seismic control cross sections of the chimneys may increase under the actions of several specific earthquake waves by considering existing eccentricities. The effect of eccentricity on the earthquake responses of tall RC chimney should be considered, and stresses caused by vertical ground motion should not be neglected to obtain accurate earthquake response of chimneys.

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In recent years, whole steel frame steel greenhouses have become increasingly prevalent. With the characteristics of large flexibility and small mass, whole steel frame steel greenhouses are sensitive to wind loads. However, studies on the safety of whole steel frame steel greenhouses under wind loads are still limited. In this study, a 10 m span whole steel frame solar greenhouse was taken as the research objective. Taking the Davenport spectrum as the target spectrum, the time history of the wind speed was simulated by the harmonic superposition method. The finite element model of the greenhouse structure was established using ANSYS software. The simulated wind pressure was applied on the greenhouse structure for dynamic response analysis. The dynamic response results were compared with the static analysis results under average wind load. The results showed that the greenhouse structure mainly bears bending stress under wind load. The bending stress, axial stress and displacement of the greenhouse skeleton under average wind loads are lower than those under instantaneous wind loads. It is necessary to consider the dynamic characteristics of wind loads in the design of solar greenhouses. A wind-induced vibration coefficient is obtained, which can be used to convert the dynamic load into the equivalent static load and improve its design efficiency.