Numerical analysis of full-scale dynamic lateral load tests of a 3 by rma97348

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                 Numerical analysis of full-scale dynamic lateral load tests of a 3 × 5pile group


                                                                                              〇 Gi-Cheon Kang, Tetsuo Tobita, Susumu Iai


Numerical analysis for interaction between soil and          Case 2, before the dynamic loading, numerical
pile group is performed using finite element method          analysis considering static loadings was conducted
with 2D modeling. Upon conducting numerical                  separately controlled by the target deflections.
analysis, model parameters for soils are taken from the      3. CONCLUSIONS
field tests and investigations at the site. In 2D analysis   Dynamic behavior of a pile group is simulated by a
response of middle 5 piles in the 3 x 5 pile group are       two–dimensional finite element analysis. Results of
simulated for a single pile and pile group. In the           the full–scale lateral–load tests of a 3 × 5 pile group
numerical analysis of the pile group, there are two          conducted in the Salt Lake City International Airport
cases. The first case is that dynamic loads without          site are compared with the simulation.
cycle static loads were sequentially applied to the pile     Overall load–deflection behavior of the pile group
group. The other is that a static load prior to dynamic      agrees well with the measured ones. When a
loads like the field test was applied at the group pile      numerical analysis includes static loadings before the
controlled by the separated target deflections.              dynamic loading (Case 2), the load-deflection curves
1. NUMERICAL MODEL                                           were larger and agree better than Case 1. Numerical
Two dimensional finite element analysis based on the         analysis overestimates the group effects in dynamic
multi–shear    mechanism constitutive        relationship,   tests and some discrepancies are found on the bending
FLIP (Iai, et al. 1992), is employed to simulate the         moment profile. This calls up further improvement of
full–scale lateral–load tests of a pile group.               a numerical modeling.
2. GROUP PILE STATNAMIC LOAD TEST                                          2500

                                                                                                                                                                          89mm Dynamic
In the full–scale tests, the statnamic tests on the                        2000                                                                                           (1st cycle)
                                                                                                                                                                                              89mm Dynamic
                                                                                                                                                                                              (16th cycle)
                                                                                                                                                                   64mm Dynamic
15–pile group were conducted simultaneously with                           1500                                                                                                          89mm Static
                                                                                                                                                              64mm Static
                                                                                                                                        38mm Dynamic
                                                              L o a d (k N )




the static loading tests (FIG. 1). The statnamic tests                     1000
                                                                                                                 25mm Dynamic
                                                                                                                                38mm Static
                                                                                             13mm Dynamic 25mm Static

were performed mainly as final loading cycles. The                             500
                                                                                          13mm Static


group pile was cyclically loaded up to certain target                            0
                                                                                      0       2000        4000        6000      8000      10000            12000       14000    16000       18000      20000

deflections after which the statnamic test was                                 -500
                                                                                                                                        Time(Sec)
performed by loading the pile group to the same target
deflection.                                                  FIG. 1. Time histories of loads applied to the full-scale test.

In Case 1, dynamic loads without cyclic static loads                             600                                                                600
                                                                                            (a) Case 1:                                                    (b) Case 2:
                                                                                 500                                                                500    13 m m
were sequentially applied to the pile group, i.e., for all                       400
                                                                                            13 m m
                                                                                                                                                    400
                                                             Load (kN)
                                                               Load (kN




                                                                                                                                         Load (kN




target deflections, except for the 1st cycle of target                           300                                                                300
                                                                                 200                                                                200
                                                                                                                                                                                        computed
deflection 89 mm. This preserves the simplicity and                              100                                  Computed
                                                                                                                      Measured
                                                                                                                                                    100
                                                                                                                                                                                        measured
                                                                                      0                                                               0
saves computational time in the numerical analysis.                             -100                                                                -100
                                                                                      0.000                                     0.015                 0.000                                      0.015
However, deflection levels after the second dynamic                                                                               Deflection (m)

loading are evaluated smaller than measured ones. In         FIG. 2. Measured and computed load versus deflection curve

								
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