{"title":"Seismic Analysis of a S-Curved Viaduct using Stick and Finite Element Models","authors":"Sourabh Agrawal, Ashok K. Jain","country":null,"institution":"","volume":26,"journal":"International Journal of Civil and Environmental Engineering","pagesStart":34,"pagesEnd":45,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/2755","abstract":"Stick models are widely used in studying the\r\nbehaviour of straight as well as skew bridges and viaducts subjected\r\nto earthquakes while carrying out preliminary studies. The\r\napplication of such models to highly curved bridges continues to\r\npose challenging problems. A viaduct proposed in the foothills of the\r\nHimalayas in Northern India is chosen for the study. It is having 8\r\nsimply supported spans @ 30 m c\/c. It is doubly curved in horizontal\r\nplane with 20 m radius. It is inclined in vertical plane as well. The\r\nsuperstructure consists of a box section. Three models have been\r\nused: a conventional stick model, an improved stick model and a 3D\r\nfinite element model. The improved stick model is employed by\r\nmaking use of body constraints in order to study its capabilities. The\r\nfirst 8 frequencies are about 9.71% away in the latter two models.\r\nLater the difference increases to 80% in 50th mode. The viaduct was\r\nsubjected to all three components of the El Centro earthquake of May\r\n1940. The numerical integration was carried out using the Hilber-\r\nHughes-Taylor method as implemented in SAP2000. Axial forces\r\nand moments in the bridge piers as well as lateral displacements at\r\nthe bearing levels are compared for the three models. The maximum\r\ndifference in the axial forces and bending moments and\r\ndisplacements vary by 25% between the improved and finite element\r\nmodel. Whereas, the maximum difference in the axial forces,\r\nmoments, and displacements in various sections vary by 35%\r\nbetween the improved stick model and equivalent straight stick\r\nmodel. The difference for torsional moment was as high as 75%. It is\r\nconcluded that the stick model with body constraints to model the\r\nbearings and expansion joints is not desirable in very sharp S curved\r\nviaducts even for preliminary analysis. This model can be used only\r\nto determine first 10 frequency and mode shapes but not for member\r\nforces. A 3D finite element analysis must be carried out for\r\nmeaningful results.","references":null,"publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 26, 2009"}