Research On Seismic Performance Of Fire Sprinkler Piping System

The construction cost of non-structural components in modern public buildings accounts for a large portion of the total investment in construction.The losses caused by the damage of non-structural components during earthquakes are often higher than those caused by structural damage.Pipeline systems are one of the important non-structural components for reducing secondary hazards after earthquakes and maintaining the normal use of buildings after earthquakes.The seismic damage to pipeline systems can result in the loss of firefighting capabilities or the failure of water supply and drainage systems,severely affecting emergency rescue and post-disaster reconstruction work.Currently,most of the experimental research on the seismic performance of fire protection pipeline systems in China is conducted at the component level using quasi-static tests,while there are relatively shaking table conducted at the system level.In addition,there is a lack of loading frameworks for suspended pipeline systems used in vibration table tests,and the numerical models of pipeline systems also need further development and improvement.Therefore,this study designs a loading framework for suspended non-structural components in vibration table tests and establishes a numerical model for the loading framework.Based on the experimental results,numerical models for seismic support hangers and pipe-joint connections are developed,and an integrated analytical numerical model including the loading framework,seismic support hangers,and pipeline connections is established for the numerical analysis of suspended fire protection pipeline systems.The main work is as follows:1.Summarizing the main damage phenomena of fire protection pipeline systems in previous earthquake damage investigations,comparing the seismic design codes for nonstructural components in various countries,and summarizing the progress of quasi-static tests,vibration table tests,and numerical simulation studies of pipeline systems to lay the foundation for subsequent research on the seismic performance of fire protection pipeline systems.2.Introducing in detail the research methods for seismic performance of suspended pipeline systems.Vibration table tests at the system level are mainly conducted by installing suspended pipeline systems in real buildings or steel structural loading frameworks for experimental research.Real buildings often simulate seismic effects by applying ground excitations,while steel structural loading frameworks often use the acceleration responses of structural floors as input.3.In order to assess the seismic performance of suspended non-structural components and reveal the seismic damage mechanisms and laws of pipeline systems under seismic actions,this study designs a practical,efficient,and reliable loading framework for suspended non-structural components.The displacement-sensitive and acceleration-sensitive seismic performance of non-structural components and equipment is studied by reproducing the inter-story displacements and floor acceleration responses of adjacent three-story structures in high-rise buildings under seismic excitations.A numerical model for the loading framework is also established.4.Twelve sets of cyclic loading tests on seismic support hangers for suspended pipeline systems are conducted to compare the effects of the installation height of the seismic support hangers,the installation angle of the diagonal braces,and the number of diagonal braces on their seismic performance.The load-carrying capacity and energy dissipation capacity of the seismic support hangers are determined,and the vulnerability curves and numerical analysis models of the seismic support hangers are established based on the experimental data,providing component parameters for establishing the numerical model of fire protection pipeline systems.5.Based on the moment-rotation hysteretic curves of pipeline connections obtained from quasi-static cyclic loading tests,a moment-rotation model for pipeline connections is established using the Pinching4 uniaxial constitutive model in the Opensees finite element software,and the model parameters are calibrated based on the experimental data.On this basis,a general moment-rotation hysteretic model for pipeline connections is further established,and recommended values for the parameters of the general hysteretic model are provided.The numerical analysis model of the pipeline system is then established using the general model,and the numerical simulation results show that this numerical model can simulate the nonlinear behavior of the pipeline system during cyclic loading with high accuracy and applicability.6.An integrated analytical numerical model including the loading framework,seismic support hangers,and pipeline connections is established for the numerical analysis of suspended fire protection pipeline systems.The results show that compared to pipeline systems using threaded hangers,the use of seismic support hangers can effectively control the displacement response of the pipeline system,and the installation height of the pipeline system and support brackets have certain effects on its displacement response.