| The characteristics of low damping and light dead weight of long-span pedestrian bridges make the structures more and more sensitive to human-induced load.Therefore,the research on human-induced vibration and structural vibration comfort level in bridge structural design is becoming increasingly important.The phenomenon of large vibration of the pedestrian bridge has occurred from time to time,which directly affects the service safety and life of the bridge structure and reduces the comfort of pedestrians.The research focus of human-induced vibration problem is to establish a reasonable walking load model.The main research contents of this paper are as follows:(1)Study on pedestrian walking parameter characteristics.Taking students of Chang ’an University as the research object,the walking parameter characteristics of pedestrians were studied through video observation experiment.The data were analyzed from the perspective of statistics,and statistically significant data was obtained,which provided the parameter basis for the random pedestrian flow model in the channelized space in the following paper.(2)A random pedestrian flow model in chanalized space is established based on cellular automata theory.This paper first introduces the definition,composition and characteristics of cellular automata and three classical cellular automata models and their applications,then describes in detail the basic parameters and evolution rules of the random pedestrian flow model in canalized space(bilegged alternations,forward,beyond and following rules),and finally establishes the random pedestrian flow model based on cellular automata theory and conducts simulation analysis.(3)Establish a random crowd load model with alternating feet(CA load model).Based on the random pedestrian flow distribution model,the walking parameter values were given and the walking load function was determined by combining the domestic and foreign scholars and the experimental data of this paper.Each cell at every moment was assigned a walking load function and allocated to the front and rear main beam nodes adjacent to the cell.Then,the load at each node of the main beam at every moment was arranged in time sequence to form the random pedestrian load time history of this node.It is the main beam joint load model(CA load model for short)under the condition of random passenger flow.(4)Taking footbridge as an example,the comfort level is analyzed and the validity of CA load model is verified.Taking the bridge as the research object,the finite element model was established,and the load time history function calculated by CA load model and EN03 standard load model was combined to check the comfort level of the bridge under a certain density.The results show that the comfort level of the bridge meets the best comfort level limit requirements of CL1,and the calculation error of CA load model and German EN03 standard load model is less than 10%,which verifies the validity of the CA load model. |
