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Lateral loads often control the design of deep foundations. This paper focuses on improving the understanding of soil-structure interaction (SSI) of laterally loaded piles and developing p-y curves based on simultaneous direct measurements of the soil-pile interaction pressure (p) and lateral pile displacement (y) along the length of the pile. This paper summarizes the methodology, instrumentation, soil-pile interaction measurements, and procedure used to investigate the soil-pile interaction and to develop the directly measured p-y curves. A102 mm diameter, 1.42 m long precast concrete pile was fully instrumented with advanced sensors and installed in well-graded sand. The digital image correlation (DIC) data indicated that the soil movement in front of the pile extended up to 6.3 pile diameters (6.3D) from the pile center. The normalized measured maximum soil-pile interaction pressures closely matched the normalized pressures provided in the literature for short, stiff laterally loaded piles installed in cohesionless soils. In addition, the direct measurement-based p-y curves at different depths showed nonlinear behavior, in which the initial stiffness and ultimate soil reaction increased as the depth increased. When compared to p-y curves calculated from measured strain along the pile length, the directly measured p-y curves showed differences of ultimate soil reaction ranging from 8% to 33%. When compared to p-y curves calculated using the procedures available in the literature, the measurement-based p-y curve ultimate soil reactions have differences ranging from 5% to 189%. The differences in ultimate soil reaction could be mainly attributed to the installation method. Key words: soil-structure interaction (SSI), active laterally loaded pile, p-y curves, digital image correlation (DIC). La conception des fondations profondes repose souvent sur un chargement lateral applique sur celles-ci. Le present article vise a ameliorer la comprehension des interactions sol-structure (SSI) au niveau pieux soumis a un chargement lateral et a tracer des courbes p-y a partir de mesures directes et simultanees de la pression d'interaction sol-pieu (p) et du deplacement lateral du pieu (y) le long de ce dernier. L'article presente sous forme resumee la methodologie, l'instrumentation et la procedure utilisees ainsi que les mesures de l'interaction sol-pieu, afin d'analyser cette meme interaction et tracer les courbes a partir des mesures directes de p et y. Un pieu prefabrique en beton de 102 mm de diametre et 1,42 m de long a ete entierement equipe de capteurs perfectionnes et installe dans un sable de granulometrie continue. Les donnees de correlation d'images digitales (DIC) ont montre que le sol, a l'avant du pieu, s'etait deplace sur une distance maximale egale a 6,3 fois le diametre du pieu (6,3D) a partir du centre du pieu. Les mesures normalisees des pressions maximales d'interaction sol-pieu coincidaient bien avec celles fournies par la litterature dans le cas de pieux courts, rigides, soumis a un chargement lateral et installes dans des sols sans cohesion. En outre, les courbes tracees a partir des mesures directes de p et y pour differentes profondeurs ont mis en evidence un comportement non lineaire se caracterisant par une augmentation de la rigidite initiale et de la reaction maximale du sol lorsque la profondeur augmentait. Lorsqu'on les a comparees aux courbes p-y tracees a partir des mesures de contrainte effectuees le long du pieu, les courbes p-y obtenues a partir des mesures directes ont revele des differences de reaction maximale du sol comprises entre 8 et 33 %. De plus, quand on a compare les courbes p-y obtenues a l'aide de mesures a celles tracees selon les procedures decrites dans la litterature, on a mis en evidence des differences de reaction maximale du sol comprises entre 5 et 189 %. Les differences de reaction maximale du sol seraient principalement dues a la methode d'installation adoptee. [Traduit par la Redaction] Mots-cles: interaction sol-structure (SSI), pieu actif soumis a un chargement lateral, courbes p-y, correlation d'images digitales (DIC)., Introduction Lateral loads often control the design of deep foundations supporting heavy buildings, bridges, transmission lines, highway facilities, and offshore structures. The most common method used to understand the soil-structure [...]

A frequency response function-based damage identification method is presented that accurately identifies both the location and severity of damage in structural systems using a limited amount of measurement information. Damage is identified by minimizing the error between measured and analytically computed frequency response functions obtained through finite element model updating. The impact that the type of genetic algorithm representation has on performance is evaluated for a fixed representation and an implicit redundant representation, which simplifies the search by exploiting the unstructured nature of damage identification. The performance of the proposed damage identification method is evaluated for beam and frame structures that consider different damage scenarios and measurement layouts. The impact of measurement noise on performance is also investigated. The damage identification method developed using the implicit redundant genetic algorithm provides greater accuracy in identifying the location and severity of damage in all case studies even in the presence of noise. For larger frame structures, the implicit redundant genetic algorithm performed well, while no valid results were obtained using the fixed genetic algorithm representation. DOI: 10.1061/(ASCE)0733-9445(2007) 133:3(449) CE Database subject headings: Damage assessment; Evolutionary computation; Frequency response; Optimization; Steel structures; Algorithms.

Granular column ground-improvement methods are widely used to improve bearing capacity and provide a drainage path. However, the behavior of granular columns depends on the confinement provided by the surrounding soil, which limits their use in poor soils. A new ground-improvement method is proposed using pervious concrete piles to provide high permeability while also providing higher stiffness and strength, which are independent of surrounding soil confinement. Building on prior research on the behavior of vertically loaded pervious concrete piles and granular columns, this paper investigates the behavior of laterally-loaded pervious concrete piles and the effects of installation on their response. Two fully-instrumented lateral load tests were conducted on a precast and cast-in-place pile using different installation methods. Advanced sensors measured the soil-structure interaction during installation and under lateral loading. Test results confirmed that laterally-loaded pervious concrete ground-improvement piles behave as flexible laterally-loaded piles, while still providing permeability similar to granular columns. Although the ultimate load capacity of the two piles was not affected by installation, the cast-inplace pile had 55% of the displacement of the precast pile at ultimate load, which indicates soil densification and lateral compression due to installation. The directly-measured p-y curves for the cast-in-place pile also better matched the existing procedures developed for driven piles and showed a higher stiffness and ultimate soil reaction than the precast pile. Results also determined that the zone of soil affected by installation extended to 2.5 D from the pile surface. [ABSTRACT FROM AUTHOR]

This paper investigates the multi-objective optimization of active control systems for vibration control of three-dimensional (3D) high-rise buildings under a variety of earthquake excitations. To this end, a novel multi-objective genetic algorithm is developed through the integration of the best features of a non-dominated sorting II (NS2) genetic algorithm (GA) and an implicit redundant representation (IRR) GA. The proposed NS2-IRR GA finds not only minimum distributions of both actuators and sensors within structures, but also minimum dynamic responses of 3D structures. Linear quadratic Gaussian controllers, hydraulic actuators and accelerometers are used for implementation of active control systems within the 3D buildings. To demonstrate the effectiveness of the proposed NS2-IRR GA, two 3D building models are investigated using finite element methods, including low- and high-rise buildings. It is shown that the proposed NS2-IRR GA is effective in finding not only optimal locations and numbers of both actuators and sensors in 3D buildings, but also minimum responses of the 3D buildings. The simulation also shows that the control performances of the proposed approach significantly enhance those of the engineering judgment oriented benchmark layout, which is validated by comparisons of each performance using the same number of actuators. [ABSTRACT FROM PUBLISHER]

SUMMARY Active control efficiency is highly dependent on the control algorithm and device types as well as the locations of the devices and sensors in a building. A gene manipulation, multi-objective genetic algorithm is proposed to optimize the placement of active devices and sensors in frame structures to reduce active control cost and increase the structural control strategy's effectiveness. Gene manipulation uses engineering judgment to modify the encoded variable information defining the number of devices and sensors per floor in selected Pareto-optimal front individuals. The proposed methodology evolves Pareto-optimal layouts that minimize the number of devices/sensors used while also minimizing the building interstory drift for a 20-story steel-frame building under earthquake loading. The results indicate that the number and location of the devices and sensors in the layouts obtained strongly depends on the desired maximum drift. Also, the location of the sensors significantly impacts the efficiency of the active controller in reducing interstory drifts. In simulation trials, the proposed gene manipulation method obtained layouts that distributed devices and sensors more evenly over the building height than layouts obtained using standard multi-objective methods, resulting in greater control efficiency. The primary benefit of implementing the proposed gene manipulation was in reducing the number of multi-objective genetic algorithm generations required by up to 40% without negatively impacting the quality of Pareto-optimal device/sensor layout solutions obtained. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The accuracy of many damage identification methods depends significantly on the quality of measurements collected by sensors, such as accelerometers, concerning the response characteristics of a structure. Often the number of sensors used to collect measurements is limited due to available funds, equipment, and access. In addition, the excitation location can significantly affect a sensor's ability to collect quality measurement information. Therefore, both the location and number of sensors and the location of the excitation must be optimized to maximize the quality of information collected. A multi-objective optimization approach is presented that minimizes the number of sensors specified while maximizing the sensitivity of the frequency response functions (FRFs) collected at each specified sensor location with respect to all possible damaged structural elements. The multiple Pareto-optimal sensor/excitation layouts obtained aid in determining the number of sensors required to obtain an effective level of measurement information. The benefit of using Pareto-optimal sensor/excitation layouts is investigated by using the optimized layouts to collect measurement information for a FRF-based structural damage identification method. Trial results confirm that an increase in damage identification accuracy and efficiency is achieved when Pareto-optimal sensor/excitation layouts are used instead of nonoptimal layouts. In addition, the Pareto-optimal layouts improved damage identification accuracy in noisy measurement environments due to increasing the quality of measurements collected. [ABSTRACT FROM AUTHOR]

The article the authors insights on the article "Interaction between Laterally Loaded Pile and Surrounding Soil," by Lusu Ni, Hai Lin, Anne Raich, and Muhannad T. Suleiman. Topics discussed include the use of the pressure distribution to simplify the analysis about pile rotation, the use of pressure sensors to measure soilpile interaction pressure, and the procedure of soil preparation.