| Exterior thermal insulation composite system(ETICS)has been widely used in China's residential external thermal insulation system and energy-saving reconstruction projects in old residential thermal insulation due to its mature technology and outstanding thermal insulation effects.In recent years,high altitude falling accident of the external thermal insulation system have occurred frequently,it exist potential safety hazard.By researching the failure mechanism of external insulation system of polystyrene board under seismic action,it is of practical significance to improve and upgrade the system more effectively in structural construction and construction technology,so as to reduce its influence of the main structure.it reduce the casualties and property losses caused by its shedding damage.The cyclic loading tests on one concrete frame structure and four concrete frame building with masonry infill walls and ETICS are carried out,in order to observe the destruction process and failure mechanism of ETICS.the result of examination is analyzed and contrasted.The test parameters included:different infill-block types(clay air-brick,aerated concrete block)and paste method and paste area.it offer recommendations for improvement of ETICS aseismatic performance.we can have some conclusion:(1)Failure mechanism of the frame wall structure filled with masonry and ETICS is mainly manifested on the capital column failure in shear.There are several reason:ETICS strengthen equvalent bracing of wall;stirrup reinforcement ratio cannot resist the additional shear stress;stiffness degradation caused by lack of restrictions on lateral displacement of frame columns.the design thickness of the cement mortar screed-coat should be reduced.It is advisable to choose 50%-70% of the paste area of the polystyrene board,which not only ensures the safety of the outer insulation board,but also prevents making the wall rigid.so,it should be increase the amount of hoop at the top of the frame column or adopt appropriate reinforcement stirrups to increase the shear capacity of the column top.(2)destruction of polystyrene board's external thermal insulation decorative layer were located at the junction of the frame and the wall.It was caused by the relative displacement and connecting bar extracting from the frame structure wall.we should increase the depth of connecting bar in order to improve the overall seismic performance of the framed wall filledwith reinforced concrete.it should be increased the number of wall tie bars or the anchoring depth into the frame column.When walls severely damaged,the ties can play an important role in supporting and drawing the wall.It can be preventing wall collapse effectively.(3)External insulation board paste rate is a necessary condition to the system security.fifty percent of Paste area can ensure that the decorative layer of the polystyrene board external insulation board would not be severely damaged under earthquake action.(4)Adopting the method of disconnecting the outer insulation board at the junction of the infill wall and the frame is important to ensure the safety of the polystyrene board outer insulation system.we should set up deformation joints of polystyrene board thermal insulation decorative layer,it can be deformed freely under earthquakes,it have capability of reducing the possibility of damage.(5)Filled wall with polystyrene board exterior insulation system reduces Reliability of Story-Drift Capacity of Aseismatic RC Frames.The displacement-angle between floors is small,resisting progressive collapse of the examples of RC frame structures is low.it has bad ductility performance.(6)Filled wall with ETICS greatly improves the ultimate loading capacity of the frame and the initial stiffness of frame.The higher pasting rate has no effect on the ultimate loading capacity of the frame obviously. |
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