Design criteria for post and beam bents with drilled shafts - Page 124 |
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110
direction. This situation was especially evident during testing the circular pile cases and
may be due to the unleveled surface of the bottom of the cap beam acquired during the
casting process. During the different loading cases in for the circular and square piles,
the difference in the rotational stiffness became less and less as the pile was
pushed/ pulled further away. This trend may indicate a threshold rotational stiffness in the
case of the concrete piles at very large pile displacements. The stiffness results for the H-pile
remained largely uniform throughout the lateral loading protocol.
It can also be noticed that the secant rotational stiffness is higher for the square pile cases
with Type VI pad. The square pile is stiffer than both the circular and HP piles, which is
contributing more to the stiffness of the connection. Similarly, the Type VI pad has a
higher shear modulus which provides a higher resistance to the lateral force, and thereby
increasing the stiffness of the connection. As the axial load on the bearing pad and pile
was increased, the rotational stiffness also increased.
Summary
This performance testing program aimed at characterizing the rotational stiffness of the
sub- super structure connection within the bridge system taking into the account the
relative stiffness of the other components. For this program, a slice of a deck- girder-diaphragm-
sole plate- anchor bolt- bearing pad- bent cap- pile bridge system was
constructed upside down to test the longitudinal behavior of the substructure to
superstructure connection in full scale. Loading was displacement controlled and was
monitored using 55 separate measuring devices. The full scale test results for the various
loading cases for each pile can be found in Appendix A.
The results from the full scale testing show the capability of this type of connection to
sustain and transfer the applied moments. Given the test components strength and
stiffness parameters, it was found from test observations that the weakest link in this
connection was the steel sole plates located at the top of the bearing pads. As these plates
were bent during load application, crushing of the concrete occurred at the diaphragm
area. Under the applied lateral loads, the sole plates bending action lead to pulled out of
the embedded plate on the girder. The embedded plate has four studs of 178 mm ( 7 in) in
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| Title | Design criteria for post and beam bents with drilled shafts - Page 124 |
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| Full Text | 110 direction. This situation was especially evident during testing the circular pile cases and may be due to the unleveled surface of the bottom of the cap beam acquired during the casting process. During the different loading cases in for the circular and square piles, the difference in the rotational stiffness became less and less as the pile was pushed/ pulled further away. This trend may indicate a threshold rotational stiffness in the case of the concrete piles at very large pile displacements. The stiffness results for the H-pile remained largely uniform throughout the lateral loading protocol. It can also be noticed that the secant rotational stiffness is higher for the square pile cases with Type VI pad. The square pile is stiffer than both the circular and HP piles, which is contributing more to the stiffness of the connection. Similarly, the Type VI pad has a higher shear modulus which provides a higher resistance to the lateral force, and thereby increasing the stiffness of the connection. As the axial load on the bearing pad and pile was increased, the rotational stiffness also increased. Summary This performance testing program aimed at characterizing the rotational stiffness of the sub- super structure connection within the bridge system taking into the account the relative stiffness of the other components. For this program, a slice of a deck- girder-diaphragm- sole plate- anchor bolt- bearing pad- bent cap- pile bridge system was constructed upside down to test the longitudinal behavior of the substructure to superstructure connection in full scale. Loading was displacement controlled and was monitored using 55 separate measuring devices. The full scale test results for the various loading cases for each pile can be found in Appendix A. The results from the full scale testing show the capability of this type of connection to sustain and transfer the applied moments. Given the test components strength and stiffness parameters, it was found from test observations that the weakest link in this connection was the steel sole plates located at the top of the bearing pads. As these plates were bent during load application, crushing of the concrete occurred at the diaphragm area. Under the applied lateral loads, the sole plates bending action lead to pulled out of the embedded plate on the girder. The embedded plate has four studs of 178 mm ( 7 in) in |
