scholarly journals MODELISASI ANALISIS NUMERIK GAYA LATERAL PADA ELEVATED REINFORCED CONCRETE PILE CAP PADA TANAH NON KOHESIF

Author(s):  
Alvin Lo ◽  
Hendy Wijaya ◽  
Amelia Yuwono

Bridges are construction structures that are built to connect parts of the road that are cut off by obstacles such as deep valleys, irrigation channel paths. In order to build a bridge, a strong, economical and easy to build foundation is needed to carry gravity loads and also earthquake force. A common problem encountered in bridge foundation is the occurrence of erosion around the piles due to scouring of water which causes exposing some portion of the piles, which are often referred as elevated reinforced concrete pile-cap foundations. In this study, a numerical analysis of pile groups on elevated reinforced concrete pile-cap foundations is carried out with lateral forces on sandy soil to see the ductility behavior of piles using geotechnical-based programs and to compare the results with the previous studies. The analysis includes the pilecap model and the soil-to-pile interaction and also considers the pile group effect. The analysis was carried out to see the structural and geotechnical conditions on the ductility behavior of a partially embedded piles on sandy soil. The result obtained is a comparison of the ductility and overstrength values that can be used as a consideration in designing elevated reinforced concrete pile-cap foundations.Keywords: Elevated RC pile-cap foundations; numerical analysis; lateral force; ductility AbstrakJembatan adalah struktur konstruksi yang dibangun untuk menghubungkan bagian jalan yang terputus oleh rintangan-rintangan seperti lembah yang dalam, alur saluran irigasi. Untuk membangun sebuah jembatan, diperlukan fondasi yang kuat, ekonomis dan mudah untuk dibangun untuk memikul beban dari jembatan dan juga gaya gempa. Masalah yang umum ditemui pada konstruksi fondasi jembatan adalah terjadinya erosi pada sekitar fondasi dikarenakan gerusan air yang menyebabkan tanah terangkat dan memperlihatkan sebagian tiang fondasi, yang sering disebut dengan elevated reinforced concrete pile-cap foundations. Pada penelitian ini dilakukan analisis secara numerik terhadap kelompok tiang pada elevated reinforced concrete pile-cap foundations yang dibebani gaya lateral pada tanah berpasir untuk melihat perilaku daktilitas tiang dengan bantuan program berbasis geoteknik dan membandingkan dengan hasil penelitian terdahulu. Analisis menyertakan model kepala tiang dan hubungan antara tanah dengan tiang serta mempertimbangkan efek kelompok tiang. Analisis dilakukan untuk melihat kondisi struktural dan geoteknikal pada perilaku daktilitas fondasi yang ditanam sebagian pada tanah pasir. Hasil yang didapatkan adalah perbandingan nilai daktilitas dan overstrength yang dapat digunakan sebagai pertimbangan dalam mendesain elevated reinforced concrete pile-cap foundations.

2020 ◽  
Vol 20 (4) ◽  
pp. 207-217
Author(s):  
Yongjin Choi ◽  
Jaehun Ahn

The <i>p-y</i> curve method and </i>p</i>-multiplier (<i>P<sub>m</sub></i>), which implies a group effect, are widely used to analyze the nonlinear behaviors of laterally loaded pile groups. Factors affecting <i>P<sub>m</sub></i> includes soil properties as well as group pile geometry and configuration. However, research on the change in <i>P<sub>m</sub></i> corresponding to soil properties has not been conducted well. In this study, in order to evaluate the effect of soil properties on the group effect in a laterally-loaded pile group installed in sandy soil, numerical analysis for a single pile and 3×3 pile group installed in loose, medium, and dense sand, was performed using the 3D numerical analysis program, Plaxis 3D. Among the factors considered in this study, the column location of the pile was the most dominant factor for <i>P<sub>m</sub></i>. The effect of the sand property change on <i>P<sub>m</sub></i> was not as significant as that of the column location of the pile. However, as the sand became denser and the friction angle increased, the group effect increased, leading to a decrease in <i>P<sub>m</sub></i> of approximately 0.1. This trend was similar to the result reported in a previous laboratory-scale experimental study.


Author(s):  
Michael C. McVay ◽  
Limin Zhang ◽  
Sangjoon Han ◽  
Peter Lai

A series of lateral load tests were performed on 3×3 and 4×4 pile groups in loose and medium-dense sands in the centrifuge with their caps located at variable heights to the ground surface. Four cases were considered: Case 1, pile caps located above the ground surface; Case 2, bottom of pile cap in contact with the ground surface; Case 3, top of pile cap at the ground surface elevation; and Case 4, top of pile cap buried one cap thickness below ground surface. All tests with the exception of Case 1 of the 4×4 group had their pile tips located at the same elevation. A special device, which was capable of both driving the piles and raining sand on the group in flight, had to be constructed to perform the tests without stopping the centrifuge (spinning at 45 g). The tests revealed that lowering the pile cap elevation increased the lateral resistance of the pile group anywhere from 50 to 250 percent. The experimental results were subsequently modeled with the bridge foundation-superstructure finite element program FLPIER, which did a good job of predicting all the cases for different load levels without the need for soil–pile cap interaction springs (i.e., p-y springs attached to the cap). The analyses suggest that the increase in lateral resistance with lower cap elevations may be due to the lower center of rotation of the pile group. However, it should be noted that this study was for pile caps embedded in loose sand and not dense sands or at significant depths. The experiments also revealed a slight effect for the case of the pile cap embedded in sand with a footprint wider than the pile row. In that case the size of the passive soil wedge in front of the pile group, and consequently the group’s lateral resistance, increased.


2014 ◽  
Vol 8 (1) ◽  
pp. 450-454 ◽  
Author(s):  
Ling Yuhong ◽  
Lin BiaoYi ◽  
Ke Yu ◽  
Chen QingJun

This paper introduced the reconstruction practice and detailing of a high-rise reinforced concrete frame-shear wall structure. To fully utilize the old structure and meet the requirement of the reconstructed structure, certain measures have been put forward. The enlarging of concrete pile cap and adding strip foundation-beam were used to support the new added shear wall. The reconstruction concept detailing of the roof of basement, the enlarging of the beam or column sections and the application of the inclined column are introduced. The whole structure analysis shows that the reconstructed structure is safe enough to meet all the requirement of the designing code and the settlement observation shows that the deformation of the whole structure in gravity is small. The paper shows the design and detailing of the reconstructed engineering is effective and will be valuable to the similar engineering structures.


2007 ◽  
Vol 23 (2) ◽  
pp. 173-180
Author(s):  
W.-Y. Lu

AbstractAn analytical model for determining the shear strength of concrete pile caps under the failure mode of diagonal-compression originally based on the softened strut-and-tie model is proposed. The failure probabilities of reinforced concrete pile caps are investigated by Monte Carlo method. The results indicate that the proposed model can accurately predict the shear strength of the pile caps. The distribution of the failure probabilities for pile caps designed to ACI 318-02 Appendix A and the proposed design method are more uniform than that designed to the ACI 318-99. The ACI 318-99 is very conservative and cannot provide a consistent safety for pile caps design. It is suggested that the procedures in the ACI 318-02 Appendix A should be moved to the main body of ACI 318-02 and the proposed design method should be incorporated into the current reinforced concrete pile cap design methods.


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