| External thermal insulation technology of building exterior wall is an important measure to realize building energy saving in today's construction industry.However,during the use of the external wall thermal insulation system,it is not uncommon for the thermal insulation layer to fall off in a large area due to the influence of strong winds,and it is showing an increasing trend.The main reason is the insufficient bonding performance between the insulation board and the base layer or the fatigue damage of the insulation board under the action of wind load.Therefore,it is of great practical significance to study the bonding fatigue properties of thermal insulation boards in external wall thermal insulation systems to improve the safety and durability of external wall thermal insulation systems.In this paper,the tensile bearing capacity and bond fatigue properties of expanded perlite thermal insulation boards are studied by means of experimental research,bond fatigue life analysis and numerical simulation.The main contents and conclusions are as follows:(1)The tensile test and the bonding fatigue performance test of the thermal insulation board of the external thermal insulation system of the expanded perlite board were carried out.Tensile tests and fatigue tests were carried out on the expanded perlite insulation board under the action of different bonding methods,different bonding areas and different fatigue load peaks to study its tensile bearing capacity and fatigue performance.The research results show that: under the same construction conditions,the order of tensile bearing capacity from high to low is full sticking method,strip sticking method,cross sticking method,point frame sticking method,point sticking method.The fatigue times of the insulation board is positively correlated with the sticking rate,and negatively correlated with the peak fatigue load;the order of the three factors affecting the fatigue times is the bonding rate,the peak fatigue load,and the bonding method;the full bonding method on the concrete base.The fatigue performance of the full-bond method on the concrete base is the best,followed by the strip-bond method with a bonding rate of 80% on the masonry base,and its fatigue times are 91% of the full-bond method on the concrete base.(2)The bond fatigue life of expanded perlite insulation boards was evaluated based on fatigue damage theory.Frequency analysis of the actual wind speed in Jinan from 2016 to 2020 and considering the influence of building height changes.The cumulative damage value of the insulation board at different heights under the conditions of the full adhesion method and the adhesion rate of 80% and 40% of the strip adhesion method was obtained.The evaluation of the bonding fatigue life of thermal insulation boards is carried out by the fatigue damage theory.The research results show that: under the same pasting method,with the increase of building height,the fatigue life of the insulation board from a height of less than 20 m to a height of 100 m is reduced by about 0.5%;the fatigue life of the strip bonding method with a bonding rate of 40% is shorter,about 8.5 years,followed by the strip bonding method with a bonding rate of 80%,the fatigue life is about 32 years,and the bonding fatigue life of the full bonding method is longer,about 50 years.(3)Numerical simulation analysis of the mechanical properties of the thermal insulation board was carried out.Through the ANSYS entity modeling of the insulation board,the loading simulation is carried out according to the wind suction load and the tensile bearing capacity,and the stress and strain of the model are analyzed.The analysis results show that during the actual use of the external wall thermal insulation system,under the action of positive and negative wind pressure,the stress at the corners of the thermal insulation board is relatively large,causing local damage and damage.Causes damage to the external insulation system.Under the action of wind suction load,the part with the largest deformation when the full-bond method is loaded is the front(outer surface)of the insulation board,and the part with the largest stress is the four corners.The largest deformation of the strip bonding method appears on the front(outer surface)of the unbonded part of the insulation board,and the part with the greatest stress is the junction of the bonded and unbonded parts on the back.When the full-bond method and the strip-bond method are loaded without the corner and edge bonding ratio,the most deformed parts are the corners.The maximum stress occurs at the junction of the bonded and unbonded parts on the back.In the case of strip bonding,a through cavity is generated,and the stress at both ends of the through cavity is second only to the stress at the junction of the bonded part. |
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