The goal of the project is to develop, build, and test a modular steel structure that can be tested on an educational shaking table to demonstrate structural dynamic and earthquake engineering principles. The advantage of the structure is that it can be tested into its non-linear range and yielded parts can easily be replaced for subsequent tests. The steel modular structure represents a multi-story moment resisting frame and is comprised of sheet metal beams and columns bolted to “rigid” steel angles. This structure is tested on a unidirectional shaking table, viz. “Quanser Shake Table II”. The structure is designed to achieve a specific mode of failure through non-linear analysis. A non-linear pushover analysis is carried out to determine stiffness and strength of the structure as well as potential hinge locations. Eigen-value analysis is undertaken to determine all the natural periods and frequencies that will help in understanding its dynamic response. The structure is analyzed and tested for various ground motions to study the effects of an earthquake on a multi-storied frame. Educational modules provide a set of experiments that can be easily performed on the test structure. / text

In this research, the dynamic behavior of a seismic isolation system composed of high strength geotextile placed over an ultra-high molecular weight polyethylene (UHMWPE) geomembrane (together called as composite liner) beneath the structure is investigated experimentally. The results of the shaking table experiments which were performed on model structures both under harmonic and modified earthquake motions with and without the seismic isolation (composite liner system), are presented in the thesis. The main focus is given on the potential improvement obtained by use of the composite liner system as compared to the unisolated cases. Based on the performed experiments, it is observed that the utilization of composite liner system provides significant reduction in the accelerations and interstorey drift ratios of structures under harmonic motions while signifant drop is obtained in the spectral accelerations under earthquake motions which provide noticeable improvement in the durability of structures under dynamic effects at the expense of increased translational displacements.

Vertical inclusions of expanded polystyrene (EPS) placed behind rigid retaining walls were investigated as geofoam seismic buffers to reduce earthquake-induced loads. A numerical model was developed using the program FLAC and the model validated against 1-g shaking table test results of EPS geofoam seismic buffer models. Two constitutive models for the component materials were examined: elastic-perfectly plastic with Mohr-Coulomb (M-C) failure criterion and non-linear hysteresis damping model with equivalent linear method (ELM) approach. It was judged that the M-C model was sufficiently accurate for practical purposes. The mechanical property of interest to attenuate dynamic loads using a seismic buffer was the buffer stiffness defined as K = E/t (E = buffer elastic modulus, t = buffer thickness). For the range of parameters investigated in this study, K ≤ 50 MN/m3 was observed to be the practical range for the optimal design of these systems. Parametric numerical analyses were performed to generate design charts that can be used for the preliminary design of these systems. A new high capacity shaking table facility was constructed at RMC that can be used to study the seismic performance of earth structures. Reduced-scale models of geosynthetic reinforced soil (GRS) walls were built on this shaking table and then subjected to simulated earthquake loading conditions. In some shaking table tests, combined use of EPS geofoam and horizontal geosynthetic reinforcement layers was investigated. Numerical models were developed using program FLAC together with ELM and M-C constitutive models. Physical and numerical results were compared against predicted values using analysis methods found in the journal literature and in current North American design guidelines. The comparison shows that current Mononobe-Okabe (M-O) based analysis methods could not consistently satisfactorily predict measured reinforcement connection load distributions at all elevations under both static and dynamic loading conditions. The results from GRS model wall tests with combined EPS geofoam and geosynthetic reinforcement layers show that the inclusion of a EPS geofoam layer behind the GRS wall face can reduce earth loads acting on the wall facing to values well below those recorded for conventional GRS wall model configurations. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-28 16:56:57.084

Cemented paste backfill (CPB) is a novel technology developed in the past few decades to better manage mining wastes (such as tailings) in environmentally friendly way. It has received prominent interest in the mining industry around the world. In this technology, up to 60% of the total amount of tailings is reused and converted into cemented construction material that can be used for secondary support in underground mine openings (stopes) and to maximize the recovery of ore from pillars. CPB is an engineered mixture of tailings, water, and hydraulic binder (such as cement), that is mixed in the paste plant and delivered into the mine stopes either by gravity or pumping. During and after placing it into the mine stopes, the performance of CPB mainly depends on the role of the hydraulic binder, which increases the mechanical strength of the mixture through the process of cement hydration. Similar to other fine-grained soils undergoing cementations, CPB’s behavior is affected by several conditions or factors, such as cement hydration progress (curing time), chemistry of pore water, mixing and curing temperature, and filling strategy. Also, it has been found that fresh CPB placed in the mine stopes can be susceptible to many geotechnical issues, such as liquefaction under ground shaking conditions. Liquefaction-induced failure of CPB structure may cause injuries and fatalities, as well as significant environmental and economic damages. Many researches studied the effect of the aforementioned conditions on the static mechanical behavior of CPB. Other researches have evaluated the liquefaction behavior of natural soils and tailings (without cement) during cyclic loadings using shaking table test technique. Only few studies investigated the CPB liquefaction during dynamic loading events using the triaxial tests. Yet, there are currently no studies that addressed the liquefaction behavior of CPB under the previous conditions by using the shaking table technique. In this Ph.D. study, a series of shaking table tests were conducted on fresh CPB samples (75 cm × 75 cm ×70 cm), which were mixed and poured into a flexible laminar shear box (that was designed and build for the purpose of this research). Some of these shaking table tests were performed at different maturity ages of 2.5 hrs, 4.0 hrs, and 10.0 hrs, to investigate the effect of cement hydration progress on the liquefaction potential of CPB. Another set of tests were conducted to assess the effect of the chemistry (sulphate content) of the pore-water on the cyclic response of fresh CPB by exposing cyclic loads on couple of CPB models that contain different concertation of sulphate ions of 0.0 ppm and 5000 ppm. Moreover, as part of this study, series of shaking table test was conducted on CPB samples that were prepared and cured at different temperatures of 20oC and 35oC, to evaluate the effect of temperature of the cyclic behavior of CPB. Furthermore, the effect of filling strategy on the cyclic behavior of fresh CPB was assessed by conducting set of shaking tables tests on CPB models that were prepared at different filling strategies of continuous filling, and sequential or discontinuous (layered) filling. The results obtained show that CPB has different cyclic behavior and performance under these different conditions. It is observed that the progress of cement hydration (longer curing time) enhances the liquefaction resistance of CPB, while the presence of sulphate ions diminishes it. It is also found that CPB mixed and cured in low temperature is more prone to liquefaction than those prepared at higher temperatures. Moreover, the obtained results show that adopting the discontinuous (layered) filling strategy will improve the liquefaction resistance of CPB. The finding presented in this thesis will contribute to efficient, cost effective and safer design of CPB structures in the mine areas, and will help in minimizing the risks of liquefaction-induced failure of CPB structures.

Buildings with torsional irregularity represent the main focus of many current investigations. However, despite this volume of research, there is no established framework that describes adequately the seismic vulnerability of reinforced concrete shear wall systems. In this study, the three-dimensional behavior of a particular shear-wall structure under earthquake effects was examined with regard to the nonlinear behavior of the reinforced concrete assembly and the parameters that characterize the structure exposed to seismic motion for damage assessment. A three story reinforced concrete shear-wall building was analyzed using the finite element method based ANSYS software. The scaled model building was subjected to shaking table tests at Saclay, France. The project was led by the Atomic Energy Agency (CEA Saclay, France) under the &ldquo / SMART 2008 Project.&rdquo / The investigation was conducted in two phases. In the first phase, the results of the finite element method and experiments were examined, and were reported in this study. For time history analysis, micro-modeling was preferred due to allowing inclusion the nonlinear effects of concrete and steel for analysis. The guiding parameters (acceleration, displacement, strain) of analytical results are compared with the corresponding values that were measured in the experiments to be able to quantify the validity of models and simulation. For the comparison of v the numerical model results with the experimental results FDE (Frequency Domain Error) method was used. After comparison of the numerical model results with the experimental results, the second phase of the SMART 2008 Project was undertaken. The second phase consisted of two parts summarized as &ldquo / Sensitivity Study&rdquo / and &ldquo / Vulnerability Analyses&rdquo / . However, in this report only the sensitivity study and fragility analyses will be reported. Sensitivity study was done to understand which parameters affect the response of the structure. Twelve parametric cases were investigated under two different ground motions. Different behavior parameters were investigated. The effective damping coefficient was found to affect the structural response at 0.2 g design level as well as at 0.6 g over-design level. At the design level, it was observed that elasticity modulus of concrete and additional masses on the specimen determined as effective on the calculated results. To derive the failure probabilities of this structure under various earthquake forces for the given limit states, fragility curves were obtained. Different seismic indicators such as PGA (Peak ground acceleration), PGV (Peak ground velocity), PGD (Peak ground displacement) and CAV (Cumulative absolute velocity) were used as seismic indicators and MISD (Maximum interstory drift) were used as damage indicator for fragility curves. In all 30 time history analyses were done. Regression analyses using least squares method were performed to determine the median capacity and its deviation. Correlation coefficients of the time history data versus fitted curves obtained from the regression analyses changes between 0.65 and 0.99. The lower cases were for PGD- MISD graphs. The scatter of the fragility curves calculated for each damage limit was slightly wider. HAZUS MH MR1 (2003) damage states were also used for the calculation of the fragility curves and compared with the SMART 2008 damage states.

Simulating the non-linear response of reinforced concrete (RC) buildings subjected to a sequence of input earthquake records, is an extremely complex concern in the field of the Earthquake Engineering. Buildings with no symmetry in plan have much more complicated behavior under earthquake effects than symmetric buildings. Torsional irregularity in plan is the main topic of many current researches. In previous decades, considerable amount of numerical and experimental studies have been conducted, but more researches are needed in order to confirm a better understanding of the concept of seismic behavior of these structures. In this study modeling and analyses efforts to simulate the experimental response of a scaled three dimensional reinforced concrete shear wall structure tested on a shaking table, are presented. The model structure is a &frac14 / scale of a three story reinforced concrete building that has torsion due to plan irregularity and layout of structural walls. In order to simulate response quantities measured for the specimen tested on a shaking table, a series of non-linear time history analyses were performed. This structure subjected to AZALEE shaking table tests in Saclay, France under the project of &ldquo / SMART 2008&rdquo / which was led by CEA (Atomic energy agency). The model building was tested under a set of bi-directional synthetic and real ground motions that have varying intensities, peak ground accelerations ranging from 0.1g to 1g. Ground motions were applied sequentially to the specimen, starting with the one having the smallest intensity. Displacements and accelerations measured at different locations on the plan at third story were compared with the numerically computed values in order to check the validity of the Finite Element Model that has been obtained in ANSYS ver.12.1.

Liquefiable soils are common at ports due to the use of hydraulic fills for construction of waterfront facilities. Liquefaction-induced ground failure can result in permanent ground deformations that can cause loss of foundation support and structural damage. This can lead to substantial repair and/or replacement costs and business interruption losses that can have an adverse effect on the port and the surrounding community. Although numerous soil improvement methods exist for remediating a liquefaction-prone site, many of these methods are poorly suited for developed sites because they could damage existing infrastructure and disrupt port operations. An alternative is to use a passive remediation technique. Treating liquefiable soils with colloidal silica gel via permeation grouting has been shown to resist cyclic deformations and is a candidate to be used as a soil stabilizer in passive mitigation. The small-strain dynamic properties are essential to determine the response to seismic loading. The small-to-intermediate strain shear modulus and damping ratio of loose sand treated with colloidal silica gel was investigated and the influence of colloidal silica concentration was determined. The effect of introducing colloidal silica gel into the pore space in the initial phase of treatment results in a 10% to 12% increase in the small-strain shear modulus, depending on colloidal silica concentration. The modulus reduction curve indicates that treatment does not affect the linear threshold shear strain, however the treated samples reduce at a greater rate than the untreated samples in the intermediate-strain range above 0.01% cyclic shear strain. It was observed that the treated sand has slightly higher damping ratio in the small-strain range; however, at cyclic shear strains around 0.003% the trend reverses and the untreated sand begins to have higher damping ratio. Due to the nature of the colloidal silica gelation process, chemical bonds continue to form with time, thus the effect of aging on the dynamic properties is important. A parametric study was performed to investigate the influence of gel time on the increase in small-strain shear modulus. The effect of aging increases the small-strain shear modulus after gelling by 200 to 300% for the 40-minute-gel time samples with a distance from gelation (time after gelation normalized by gel time) of 1000 to 2000; 700% for the 2-hour-gel time sample with a distance from gelation of 1000; and 200 to 400% for the 20-hour-gel time samples with a distance from gelation of 40 to 100. The treatment of all potentially liquefiable soil at port facilities with colloidal silica would be cost prohibitive. Identifying treatment zones that would reduce the lateral pressure and resulting pile bending moments and displacements caused by liquefaction-induced lateral spreading to prevent foundation damage is an economic alternative. Colloidal silica gel treatment zones of varying size and location were evaluated by subjecting a 3-by-3 pile group in gently sloping liquefiable ground to 1-g shaking table tests. The results are compared to an untreated sample. The use of a colloidal silica treatment zone upslope of the pile group results in reduced maximum bending moments and pile displacements in the downslope row of piles when compared to an untreated sample; the presence of the treatment zone had minimal effect on the other rows of piles within the group.

The presented research investigated the viability of a double-braided synthetic fiber rope for providing improved performance of steel moment frames subjected to earthquake-induced ground motions. A series of experimental tests, including a 1:3-scale dynamic test and 1:6-scale shaking table tests, was conducted using Northridge ground-motion input. A series of nonlinear dynamic analytical studies, using DRAIN-2DX, was conducted to develop the experimental tests. Throughout experimental testing, the ropes exhibited a hyper-elastic loading response and a reduced-stiffness unloading response. A conditioning cycle was defined as a loading cycle induced in the rope above the highest load expected to be experienced by the rope, and was determined to be requisite for ropes intended to be used for the stated objectives of the research program. After experiencing a conditioning cycle, the rope response returned to initial conditions without permanent deformation, demonstrating repeatability of response through several loading cycles below the conditioning load. In the 1:6-scale shaking-table experiments, the ropes drastically improved the performance of the steel moment frames. Maximum and residual drift were reduced significantly, with a corresponding minimal increase to the maximum base shear. Base shear was reduced at several peaks subsequent to the initial pulse of the Northridge ground-motion input. The analytical model developed was excellent for predicting elastic response of the 1:6-scale shaking table experiments and adequate for the purpose of planning shaking table studies. Correlation of peak rope forces between the analytical model and experimental results was poor, and was attributed to limitations of the pre-defined elements used to represent the rope devices in the software program. The inability of the elements to capture the complex unloading response of the rope was specifically noted. / Ph. D.

Seismic safety of underground structures (culvert, subway, natural gas and water sewage systems) plays a major role in sustainable public safety and urban development. Very few experimental data are currently available and there is not generally accepted procedure to estimate the dynamic pressures acting on underground structures. This study aims to enhance the state of prevalent information necessary in understanding the dynamic behavior of box culverts and the stresses acting under dynamic excitations through experimental analyses. For this purpose, a series of shaking table tests were conducted on box-type culverts buried in dry sand. To simulate the free-field boundary conditions, a laminar box was designed and manufactured for use in a 1-g shake table. Four culvert models having different rigidities were tested under various harmonic motions in order to examine the effect of flexibility ratio on dynamic lateral soil pressures. Based on the tests results, a simplified dynamic pressure distribution acting on sidewalls of the culvert model was suggested. Then, a dynamic lateral coefficient was defined for the proposed peak pressure value in the distribution. The values of this coefficient were obtained as a function of shear strain and relative stiffness between the soil and underground structure. Finally, a simplified frame analysis approach was suggested for the assessment of the forces on the structure, to help to carry out a preliminary design of box-type culverts. In this approach, it was assumed that the culvert was fixed at bottom and subjected to lateral stresses on sidewalls and shear stresses on the upper face. For the confirmation of the method, centrifuge tests were conducted on a box-type culvert model under the Seventh Framework Programme of European Union with Grant Agreement No.227887. Results show that the proposed simplified procedure can be used in reasonable accuracy as a practical approach for the preliminary assessment of box-type culverts buried in dry sand under seismic action.

Static and dynamic interaction mechanism of the retained soil-compressible geofoam buffer and yielding retaining structures requires further investigation. The present study, initiated on this motive, discusses the results of 1-g physical model tests and numerical analyses of cantilever retaining walls with and without deformable geofoam buffers between the wall and cohesionless granular backfill. 0.7m high walls with various wall thicknesses were utilized in the physical modeling. Dynamic tests were carried out by using a laminar container placed on a uni-axial shaking table. Influence of buffer thickness, geofoam type and wall flexibility as well as base excitation characteristics on the lateral earth pressures and flexural wall deflections were under concern. Outcomes of the analyses performed with FLAC-2D (v6.0) finite difference code were validated against the results of the physical model tests. It was observed that the arching effect induced in the retained soil by the lateral compression of the lower half of the geofoam buffer has a positive effect, as this zone is able to absorb a portion of the total unbalanced lateral force exerted by the backfill thus causing a reduction in the static and seismic lateral wall pressures. Relative thickness and stiffness of the geofoam buffer appear to be the most dominant factors affecting the reduction in earth thrust. Lateral earth pressure coefficients determined from physical model tests were compared with those calculated using methods available in the literature. Good agreement was observed between the predictions. Graphs were provided to estimate the static and dynamic lateral earth pressure coefficients for various combinations of wall stiffness and buffer characteristics. Analysis of a 6m high prototype cantilever wall subjected to an excitation recorded in August 17, 1999 Kocaeli earthquake by finite difference method exhibited the contribution of geofoam buffers on seismic performance of cantilever earth retaining walls. It was observed that the presence of an EPS geofoam inclusion provides a reduction of the permanent flexural wall deflections as well as total seismic thrust likely to be experienced by the wall during an earthquake.