DAMAGE TO BRIDGES DURING EARTHQUAKES 641 



Speaking of a bridge near the Kiso River and also near the great 

 Kisogawa bridge just referred to, the authors state that this bridge 

 consists of two spans of 70-foot plate girders, and add: 



The end walls or abutments are cut through horizontally, and .the solid brick 

 "well" v/hich supported the central pier betv/een the spans is broken across like a 

 stick. The upper portion of the v/ell has moved three feet sideways on the line 

 of fracture. 



From the photograph it v/ill be seen that while the south abutment is broken 

 through horizontally, the side walls are cracked diagonally. 



At the end of the crack v»'here it rises from the ground it was discovered, on 

 taking the brick v/ork dov/n for reconstruction that the earthquake had throv/n 

 the foundations of each v/ing wall 10 inches av^ay from the v/ell formation of the 

 abutment which originally was touching the foundations. (See Fig. 5, A.) 



Thus in this case, also, it appears that the abutments showed 

 evidences of the shortening of the distance between them in their 

 tilting back from the river. 



Probably the most interesting and instructive example yet furnished 

 of the deformation of bridges during earthquakes is that of the rail- 

 way bridge over the Nagara River (See Fig. 3, B and C). 



The main part of the bridge consists of five independent thrust girders of wide 

 span. The piers at the two ends of one of these girders are completely vt^recked 

 and the girders have fallen bodily into the bed of the river. The piers on either 

 side of the tv/o mentioned are partly v/recked, and the girders betv/een them and 

 the first-mentioned girders rest, each v/ith one end in the river bed, the other on the 

 top of the partly destroyed pier. The remaining girders are in their original 

 positions or nearly so. 



It will again be observed that the portion of the bridge which has fallen relative 

 to the part v/hich remains standing, has been thrown some distance out of a straight 

 line. 



Examination has shov.'n that this displacement is not simply a displacement 

 of the upper-v/ork of the bridge, but the ground with the screvf-pile foundations 

 has been shifted a distance of several feet up the stream. 



The embanked approach to the Nagaragawa bridge has been thrown into a 

 regular series of undulations of such extent that, looking along the line eastward 

 from the eastern abutment, the appearance is almost that of looking along a 

 switch-back railway. 



It will not fail of observation that the bridge spans, though fallen 

 in some instances from their foundations, and further shifted some 

 distance up stream, approximate to curved sections, in both horizontal 

 and vertical planes, yet maintain their continuity across the river 



