Calculation of pile foundation forces
Publish: 2021-04-03 07:15:24
1. According to the empirical method for calculating the bearing capacity of single pile under vertical load, through the bearing mechanism of composite pile foundation with single pile and single pile cap under the action of pile cap, and based on the elastic theory, a formula for calculating the bearing capacity of composite pile foundation with low pile cap is proposed, The measured value is close to the calculated value. It is proved that the calculation method of bearing capacity of composite pile foundation established in this paper is feasible on the premise of considering the load sharing effect of pile cap and the increase of pile side friction and pile end resistance e to the effect of pile cap. It can be applied and referenced by engineering circles, and it can greatly save engineering funds with remarkable economic benefits
2. Search JTG d63-2007 code for design of subgrade and foundation of highway bridges and culverts on the Internet
on page 37, the formula is not complex, and the interpretation is very complex
on page 37, the formula is not complex, and the interpretation is very complex
3. See the drawing instructions of Qiaotong
(8) internal force combination table of each column (pile) calculation section (the above five sections are calculated separately) (9) reinforcement and crack calculation table of each column (pile) calculation section (the above five sections are calculated separately) (10) calculation table of maximum bending moment in a pile soil (11) calculation table of maximum reaction force and pile length of a pile (12) calculation table of horizontal displacement of pier top (including displacement at scouring section) (calculation)
⒀ internal force table of pier cap bottom in cross bridge direction (table 14) total internal force table of pier cap bottom in cross bridge direction (table 16) internal force combination table of pier cap bottom in cross bridge direction (table 16) internal force combination table of each calculation section in cross bridge direction (table 18) internal force of each calculation section in cross bridge direction Calculation table of reinforcement and crack (19) calculation table of pile length of single pile in transverse direction of bridge (13) calculation table of maximum bending distance in single pile soil in transverse direction of bridge note: the total table refers to the addition of internal force for crack calculation, displacement calculation and pile length calculation, and the combination table refers to the addition of internal force multiplied by effect coefficient for reinforcement calculation
5.3 algorithm description
5.3.1 design specifications and standards
1) the Ministry of communications of the people's Republic of China standard jtj-001-97 for Highway Engineering (2) the Ministry of communications of the people's Republic of China standard jtj021-89 for general design of highway bridges and culverts (3) the Ministry of communications of the people's Republic of China standard jtj024-85 for design of foundation and foundation of highway bridges and culverts (4) Internal force calculation in 5.3.2 of "code for design of highway reinforced concrete and prestressed concrete JTJ023-85" of Ministry of communications of the people's Republic of China; The transverse direction of the bridge is regarded as the calculation of multi row piles. (2) the apparent load of the reaction force transferred from the upper live load to the column or pile directly acts on the cap beam structure of continuous beam mode. (3) internal force analysis of pile foundation adopts m method< (4) for simply supported structures with unequal left and right spans, the internal force calculation of single hole load distribution is only based on the left span load distribution, and the principle of double hole load distribution is to maximize the total reaction force< (5) the average braking force of each pile or column is increased by 20%, i.e. 1.2 * braking force / number of columns, so as to improve the uneven distribution of braking force to piles or columns caused by eccentric load< (6) in the calculation of displacement along the bridge to the pier top and pile reinforcement, the pile is regarded as a cantilever member, that is, the pier top is calculated in free mode. 5.3.3 in structural design
when calculating the section strength (including reinforcement), the combined value of article 4.1.2 of 85 "bridge code" is used for the calculation of internal force. The total value of internal force is used in the calculation of crack resistance of cross section and pile length of single pile, that is, the influence of load effect enhancement factor is not included. For the calculation formula of cracks, refer to the method introced on page 299 of "pier and foundation" manual, and do not check the crack resistance of small eccentric structure without tensile stress.
(8) internal force combination table of each column (pile) calculation section (the above five sections are calculated separately) (9) reinforcement and crack calculation table of each column (pile) calculation section (the above five sections are calculated separately) (10) calculation table of maximum bending moment in a pile soil (11) calculation table of maximum reaction force and pile length of a pile (12) calculation table of horizontal displacement of pier top (including displacement at scouring section) (calculation)
⒀ internal force table of pier cap bottom in cross bridge direction (table 14) total internal force table of pier cap bottom in cross bridge direction (table 16) internal force combination table of pier cap bottom in cross bridge direction (table 16) internal force combination table of each calculation section in cross bridge direction (table 18) internal force of each calculation section in cross bridge direction Calculation table of reinforcement and crack (19) calculation table of pile length of single pile in transverse direction of bridge (13) calculation table of maximum bending distance in single pile soil in transverse direction of bridge note: the total table refers to the addition of internal force for crack calculation, displacement calculation and pile length calculation, and the combination table refers to the addition of internal force multiplied by effect coefficient for reinforcement calculation
5.3 algorithm description
5.3.1 design specifications and standards
1) the Ministry of communications of the people's Republic of China standard jtj-001-97 for Highway Engineering (2) the Ministry of communications of the people's Republic of China standard jtj021-89 for general design of highway bridges and culverts (3) the Ministry of communications of the people's Republic of China standard jtj024-85 for design of foundation and foundation of highway bridges and culverts (4) Internal force calculation in 5.3.2 of "code for design of highway reinforced concrete and prestressed concrete JTJ023-85" of Ministry of communications of the people's Republic of China; The transverse direction of the bridge is regarded as the calculation of multi row piles. (2) the apparent load of the reaction force transferred from the upper live load to the column or pile directly acts on the cap beam structure of continuous beam mode. (3) internal force analysis of pile foundation adopts m method< (4) for simply supported structures with unequal left and right spans, the internal force calculation of single hole load distribution is only based on the left span load distribution, and the principle of double hole load distribution is to maximize the total reaction force< (5) the average braking force of each pile or column is increased by 20%, i.e. 1.2 * braking force / number of columns, so as to improve the uneven distribution of braking force to piles or columns caused by eccentric load< (6) in the calculation of displacement along the bridge to the pier top and pile reinforcement, the pile is regarded as a cantilever member, that is, the pier top is calculated in free mode. 5.3.3 in structural design
when calculating the section strength (including reinforcement), the combined value of article 4.1.2 of 85 "bridge code" is used for the calculation of internal force. The total value of internal force is used in the calculation of crack resistance of cross section and pile length of single pile, that is, the influence of load effect enhancement factor is not included. For the calculation formula of cracks, refer to the method introced on page 299 of "pier and foundation" manual, and do not check the crack resistance of small eccentric structure without tensile stress.
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