Comparison of reaction force and contact pressure on design truck load of slab bridge supported by MSEW abutment

보강토교대로 지지된 슬래브교의 설계 활하중에 대한 반력 및 접지압 검토

Abstract

In this study, the structural analysis was conducted to the comparison of reaction force and contact pressure on the design truck load (DB-24 and KL-510) of slab bridge supported by MSEW abutment. As a result of the structural analysis, the reaction force acting on the abutment at the continuous bridge was reduced rather than the simple span bridge. The reaction force due to the dead load was estimated to be about twice as large as that of the live load, and the influence of the live load on the total reaction force was relatively small. The contact pressure of the MSEW abutment was estimated to be the largest in the simple span bridge. The influence of contact pressure on the type of live load was relatively small. Therefore, it is considered to be more advantageous to apply the MSEW abutment to the continuous bridge than to the simple span bridge because the contact pressure acting on the abutment on the continuous bridge is estimated to be small. Since the reaction force and the load sharing ratio acting on the MSEW abutment depending on various conditions, it is necessary to examine the contact pressure in various types of bridges and specifications.

본 연구에서는 보강토교대로 지지된 슬래브교의 설계 활하중을 도로교설계기준(2010)의 DB-24와 도로교설계기준(한계상태설계법)(2015)의 KL-510으로 구조해석을 수행하였다. 구조해석 결과로부터 산정된 슬래브교의 반력과 보강토교대에 작용하는 접지압에 대해 비교검토를 수행하였다. 교대에 작용되는 반력은 교각의 유무와 개수에 따라 다르게 산정되었다. 단경간에 비해 연속교에서 교대에 작용되는 반력이 감소되는 것으로 나타났다. 구조해석 결과, 활하중보다는 고정하중에 의한 반력이 약 2배 이상 크게 산정되었으며, 활하중이 전체 반력에 미치는 영향이 상대적으로 작았다. 보강토교대에 작용하는 접지압은 단경간에서 가장 크게 산정되었다. 이동하중의 종류에 따른 영향은 상대적으로 크지 않았다. 따라서, 연속교에서 교대에 작용되는 반력과 접지압이 작게 산정되기 때문에, 단경간 교량보다는 연속 교량에 보강토교대를 적용하는 것이 유리한 것으로 판단되었다. 보강토교대에 작용되는 반력과 하중 분담률은 다양한 조건에 따라 달라지므로, 다양한 교량 형식과 제원에서의 접지압 검토가 향후 필요하다.

Fig. 1. Standard figure of true MSEW abutment [6]; (a) Cross-section view of abutment (b) Arrangement of abutment

Fig. 2. Line location of maximum tension on MSEW abutment depending on seat geometry [9]; (a) Case 1, (b) Case 2, (c) Case 3

Fig. 3. Variation of stress ratio with depth in aMSE wall [6];

Fig. 4. Cross-section view of true MSEW [1];

Fig. 5. Standard cross-section view of highway road in Korea Highway Corporation (four lanes) [1];

Fig. 6. Cross section of slab bridge; (a) Drawing of cross section (b) Drawing of longitudinal section

Fig. 7. Design truck load; (a) Korean Highway Bridge Design Code [8] (b) Korean Highway Bridge Design Code (Limit State Design) [9]

Fig. 8. Structural analysis model; (a) Simple span of length 13.5m (b) Two spans of length 27.0m (c) Three spans of length 40.5m

Fig. 9. Comparison of reaction force on the bridge according to bridge length; (a) Dead load, (b) Live load

Fig. 10. Load bearing ratio of abutment according to bridge length; (a) Korean Highway Bridge Design Code [8], (b) Korean Highway Bridge Design Code(Limit State Design)[9]

Fig. 11. Reaction force of live load and dead load onthe abutment according to bridge length

Fig. 12. Contact pressure of abutment according tobridge length

Table 1. Reaction force of bridge bearing with simple span by structural analysis

Table 2. Reaction force of bridge bearing with 2nd span by structural analysis

Table 3. Reaction force of bridge bearing with 3rd span by structural analysis

Table 4. Reaction force of the live load according tothe length of the bridge