Experimental Study On Seismic Performance Of Solar Thermal Power Tower Under Vertical Earthquake

In recent years,solar thermal power generation has been strongly advocated and studied at home and abroad due to its low cost of heat storage,safety,environmental protection and excellent power quality.In this paper,the seismic performance test under vertical earthquake is carried out for the important core structure of solar thermal power station--solar thermal power generation tower.Solar thermal power tower is a new and complex high-rise steel-concrete vertical mixed structure,with large height,complex structure inside the tower,tower wall thickness changes,the upper part has a large concentration of mass,the junction of steel structure and concrete structure due to the material and structural changes caused by the sudden change in its stiffness and other characteristics.There is a big difference in the design structure and structural performance between solar thermal power tower and common concrete chimney,water tower and other high flexible structures.Based on the actual project of a solar thermal power tower in Morocco,this paper designed and made a 1:18 scale test model of the vibration table of the solar thermal power tower,completed the vibration table test and combined with ABAQUS finite element software,studied the vertical seismic performance of the solar thermal power tower.The results show that adding lead powder can greatly increase the bulk density of particle concrete and reduce the compressive strength,tensile strength and elastic modulus of concrete.Considering the size,weight and the conditions of the shaking table,it is feasible to adopt lead-powder concrete as the model material for the substructure of the solar thermal power tower in this paper.A shaking table test was carried out on the model structure to study its dynamic characteristics and seismic performance under vertical earthquake.It is found that the vertical vibration period of the model structure is short and close to the high-frequency vibration.Under the vertical earthquake,the seismic response of the upper steel structure is obviously smaller than that of the lower concrete tube structure,and the seismic response of the model structure is mainly concentrated in the large volume of reinforced concrete in the height part of the tube 1/3 to 2/3.The finite element model was established for the shaking table test model with ABAQUS.The natural vibration frequency obtained by modal analysis was basically consistent with the test value.The time-history curves of acceleration,displacement and axial force obtained by time-history analysis were basically consistent with the trend of the test curve.By comparing the analysis results of horizontal and vertical combined seismic actions,it is found that the vertical seismic participation has little influence on the seismic response of the structure under the action of 7 degrees of fortification.Under the action of 8-degree rare earthquake,the vertical earthquake has a great impact on the horizontal displacement of the model structure,but a relatively small impact on the horizontal acceleration and bottom shear.The vertical maximum acceleration response of the structure exceeds the horizontal maximum acceleration response under the action of a three-direction earthquake rarely occurring at 8 degrees.Through the experimental study and finite element analysis in this paper,it is concluded that the influence of vertical earthquake on the seismic performance of the middle and upper part of the solar thermal power tower structure can not be ignored.The circumferential cracks in the middle and upper part of the model structure are mainly caused by the vertical seismic action.