Steel pipe pole base and reinforcing method thereof

Abstract

The present invention: provides a steel pipe pole base and a method for reinforcing the steel pipe pole base that do not allow the strength to lower in the vicinity of the weld toe of a rib even in the event of applying repeated bending moment; and is characterized by forming peening processed portions 20 by ultrasonic vibration at the weld toes 16 of tabular ribs 12 welded to the base of a steel pipe pole 10 in the form of a T-joint or the weld toes of inverted-U shaped ribs 13 or inverted-V shaped ribs 14, the ribs being bent at the upper end portions, welded to the base of a steel pipe pole 10 in the form of a T-joint. Preferable treatment conditions are 20 to 50 μm in amplitude and 10 to 50 kHz in frequency. In particular, the present invention makes it possible to remarkably improve the fatigue property because stress concentration is relaxed by the synergetic effect of bending the upper end portions 16 of the ribs 13 and applying a peening treatment.

1 . A steel pipe pole base reinforced with ribs welded to said steel pipe pole base in the form of a T-joint, characterized by forming peening processed portions at weld toes by ultrasonic vibration.  
   
   
       2 . A steel pipe pole base according to  claim 1 , characterized by said ribs being tabular ribs.  
   
   
       3 . A steel pipe pole base according to  claim 1 , characterized by said ribs being inverted-U or inverted-V shaped ribs bent at the upper end portions.  
   
   
       4 . A method for reinforcing a steel pipe pole base according to any one of  claims 1  to  3 , characterized by applying peening treatment to weld toes by ultrasonic vibration after said tabular ribs, inverted-U shaped ribs or inverted-V shaped ribs are welded to said steel pipe pole base in the form of a T-joint.  
   
   
       5 . A method for reinforcing a steel pipe pole base according to  claim 4 , characterized by applying peening treatment to said weld toes by ultrasonic vibration while a load is imposed on said steel pipe pole base so as to impose a tensile stress in the direction of the steel pipe axis on the base material in the region subjected to said peening treatment.  
   
   
       6 . A method for reinforcing a steel pipe pole base according to  claim 4 , characterized by applying said peening treatment by ultrasonic vibration under the conditions of 20 to 50 μm in amplitude and several tens of kHz in frequency.