Book•
Foundation analysis and design
01 Jan 1968-
TL;DR: In this paper, Fondation de soutenagement et al. presented a reference record for Dimensionnement Reference Record created on 2004-09-07, modified on 2016-08-08.
Abstract: Keywords: Fondation ; Mur de soutenement ; Pieux ; Capacite portante ; Ancrage ; Dimensionnement Reference Record created on 2004-09-07, modified on 2016-08-08
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TL;DR: In this article, the collapsibility effect on settlement of pile-raft foundation based on water content and cap rigidity was taken into consideration using experimental procedures, and the results revealed that in unsaturated soils, increasing the water content led to decreasing the bearing capacity of the piling system.
Abstract: Pile-raft foundation has been used to increase the bearing capacity of pile group. Most of the studies have been conducted on the pile group, and the effect of pile cap on the bearing capacity is largely neglected. The pile cap system plays an important role in increasing the bearing capacity of the cap group constructed on collapsible soils. In the present study, the collapsibility effect on settlement of pile-raft foundation based on water content and cap rigidity was taken into consideration using experimental procedures. These experiments were carried out on pile-raft, pile group, single flexible cap, and single rigid cap at different water contents. The results revealed that in unsaturated soils, increasing the water content led to decreasing the bearing capacity of the pile-raft system. Furthermore, in the saturation state, the portion of raft effect is negligible and the loads are completely tolerated by piles. The results also showed that decreasing the soil water content increased the efficiency of rigid and flexible cap, pile-raft, and free pile group. Moreover, the efficiency of the rigid pile-raft system is more than that of the flexible system, and the difference is insignificant when the water content reaches to saturation status. Finally, at similar water content and stress, the settlement of the flexible pile-raft system would be greater than that of the rigid pile-raft system.
3 citations
Dissertation•
01 Aug 1975
TL;DR: In this article, a procedure for determination of the lateral earth pressure distribution to be used for computation of forces and moments acting on retaining walls which are fixed at their base and backfilled with cohesionless sand is developed.
Abstract: A procedure for determination of the lateral earth pressure distribution to be used for computation of forces and moments acting on retaining walls which are fixed at their base and backfilled with cohesionless sand are developed. The procedure is based on the analysis of data collected from two instrumented full scale retaining walls. Data are presented covering a period of 1156 days for a cantilever wall founded on drilled shafts. The data consist of pressure cell and movement measurements for both walls. In addition, the force transmitted from the panel wall to its supporting pilasters was measured with force transducers. Structural design considerations and some recommended construction practices are included. Earth pressure distributions and wall movement data are compared with the results of Terzaghi's large scale retaining wall test. This comparison indicates that the foundation of the wall will prohibit the wall from tilting by an amount sufficient to reduce the earth pressures below the at rest value near the base of the wall. Thus for design purposes at-rest pressures are considered to act in this region. Earth pressure changes with time show a seasonal variation in pressure for both walls. The pressure on the panel wall increased as the panel moved outward after backfill. significant changes in pressure appear to result from the movement of construction equipment during backfill and afterward. However, vehicular traffic after construction did not produce measurable changes in pressure during the time periods covered. /FHWA/
3 citations
Dissertation•
01 Jan 2014
TL;DR: In this article, an evaluation of seismic responses of two instrumented three storey RC buildings under a selection of 50 earthquakes and behavioral changes after Ms=7.1 Darfield (2010) and Ms=6.3 Christchurch (2011) earthquakes for an instrumented eight story RC building was presented.
Abstract: The full scale, in-situ investigations of instrumented buildings present an excellent opportunity to observe their dynamic response in as-built environment, which includes all the real physical properties of a structure under study and its surroundings. The recorded responses can be used for better understanding of behavior of structures by extracting their dynamic characteristics. It is significantly valuable to examine the behavior of buildings under different excitation scenarios. The trends in dynamic characteristics, such as modal frequencies and damping ratios, thus developed can provide quantitative data for the variations in the behavior of buildings. Moreover, such studies provide invaluable information for the development and calibration of realistic models for the prediction of seismic response of structures in model updating and structural health monitoring studies. This thesis comprises two parts. The first part presents an evaluation of seismic responses of two instrumented three storey RC buildings under a selection of 50 earthquakes and behavioral changes after Ms=7.1 Darfield (2010) and Ms=6.3 Christchurch (2011) earthquakes for an instrumented eight story RC building. The dynamic characteristics of the instrumented buildings were identified using state-of-the-art N4SID system identification technique. Seismic response trends were developed for the three storey instrumented buildings in light of the identified frequencies and the peak response accelerations (PRA). Frequencies were observed to decrease with excitation level while no trends are discernible for the damping ratios. Soil-structure interaction (SSI) effects were also determined to ascertain their contribution in the seismic response. For the eight storey building, it was found through system identification that strong nonlinearities in the structural response occurred and manifested themselves in all identified natural frequencies of the building that exhibited a marked decrease during the strong motion duration compared to the pre-Darfield earthquakes. Evidence of foundation rocking was also found that led to a slight decrease in the identified modal frequencies. Permanent stiffness loss was also observed after the strong motion events. The second part constitutes developing and calibrating finite element model (FEM) of the instrumented three storey RC building with a shear core. A three dimensional FEM of the building is developed in stages to analyze the effect of structural, non-structural components (NSCs) and SSI on the building dynamics. Further to accurately replicate the response of the building following the response trends developed in the first part of the thesis, sensitivity based model updating technique was applied. The FEMs were calibrated by tuning the updating parameters which are stiffnesses of concrete, NSCs and soil. The updating parameters were found to generally follow decreasing trends with the excitation level. Finally, the updated FEM was used in time history analyses to assess the building seismic performance at…
3 citations
Cites methods from "Foundation analysis and design"
...The shear wave velocity, Vs, was taken as 160m/s based on the investigation for the site subsoil classification (Boon et al., 2011), the dynamic shear modulus, G, as 47MPa, and Poisson’s ratio, µ, as 0.4, considering the recommendations from Bowles (1996)....
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01 Jan 2018
TL;DR: In this paper, the authors discuss the recent advances in soil dynamics, especially in the area of geotechnical earthquake engineering, and discuss the aspects which need to be considered in liquefaction potential evaluation.
Abstract: Evidences from past earthquakes clearly show that the damages due to an earthquake and its severity at a site are controlled mainly by three factors, i.e., earthquake source and path characteristics, local geological and geotechnical characteristics, and structural design and quality of the construction. Seismic ground response at a site is strongly influenced by local geological and geotechnical conditions. The exact information of the geological, geomorphological, and geotechnical data along with seismotectonic details at a particular site are necessary to evaluate the ground response. The geometry of the subsoil structure, the soil type, the lateral discontinuities, and the surface topography will also influence the site response at a particular location. Since the seismic effects on the structure depend fully on the site conditions, research in the area of soil dynamics becomes more useful. The first input required in evaluation of geotechnical aspect of seismic hazard is the rock-level peak horizontal acceleration (PHA) values. The surface-level acceleration values need to be calculated based on the site conditions and site amplification values. This chapter discusses the recent advances in soil dynamics, especially in the area of geotechnical earthquake engineering. The topics covered in this chapter include various methods for evaluating the local site effects, dynamic soil properties, different field and laboratory tests required, various site classification schemes, and different methods to evaluate the surface-level ground motion. In addition to this, the aspects which need to be considered in liquefaction potential evaluation are also discussed.
3 citations
Journal Article•
TL;DR: In this article, an improvement of the weak soil surround the pile and observing the effect of improvement on pile capacity for bored pile was proposed. But the improvement suggested in this study is compacting and replacement for surrounding soil.
Abstract: There is very close relation between the pile capacity and surrounding soil conditions. In cohesionless soil the bored pile effected on surround soil byloosen , deposits through a combination of pile volume replacement and exist of pile case used for installation of bored pile. .the pile foundation usually designed to exceed the weak soil to the firm deposit .in this study improvement of the weak soil surround the pile and observing the effect of improvement on pile capacity for bored pile. The improvement soil surround pile model was design to be as one block and kept this block will effect noticeably on pile load capacity results. the improvement suggested in this study is compacting and replacement for surrounding soil . for this purpose testing program prepared by selection two types of sand soil one as the origin soil and the other as improving soil (soil will be compacted and replace surround pile model) . pile model prepared for this purpose is consist of reinforcement steel bar covered with cement mortar ,50 kN automatic electromechanical compression machine was used for testing load- settlement test on pile model. testing procedure includes changing the diameter of compacted soil around pile model and execute the load settlement test and compare the results with each other and with results obtained from Hansen equation.
3 citations