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With the rise in constructing using FRP reinforcement, owing to corrosion problems in steel-reinforced structures, there is a need for a system to resist lateral loads induced from wind and earthquake loads. The present study addressed the applicability of reinforced-concrete shear walls totally reinforced with glass-fiber-reinforced polymer (GFRP) bars to attain reasonable strength and drift requirements as specified in different codes. Four large-scale shear walls - one reinforced with steel bars (as reference specimen) and three totally reinforced with GFRP bars - were constructed and tested to failure under quasi-static reversed cyclic lateral loading. The GFRP-reinforced walls had different aspect ratios covering the range of medium-rise walls. The reported test results clearly showed that properly designed and detailed GFRPreinforced walls could reach their flexural capacities with no strength degradation, and that shear, sliding shear, and anchorage failures were not major problems and could be effectively controlled. The results also showed recoverable and self-centering behavior up to allowable drift limits before moderate damage occurred and achieved a maximum drift meeting the limitation of most building codes. Acceptable levels of energy dissipation accompanied by relatively small residual forces, compared to the steel-reinforced shear wall, were observed. Finite element simulation was conducted and the analyses captured the main features of behavior. Interaction of flexural and shear deformations of the tested shear walls was investigated. It was found that relying on the diagonal transducers tended to overestimate shear distortions by 30% to 50%. Correcting the results based on the use of vertical transducers was assessed and found to produce consistent results. Decoupling the flexural and shear deformations was discussed. Using GFRP bars as elastic material gave uniform distribution of shear strains along the shear region, resulting in shear deformation ranging from 15 to 20% of total deformation. The yielding of the steel bars intensified the shear strains at the yielding location, causing significant degradation in shear deformation ranging from 2 to 40% of total deformation. The results obtained demonstrated significantly high utilization levels of such shear wall type, therefore, primary guidelines for seismic design of GFRP-reinforced shear wall in moderate earthquakes regions was presented, as no design guidelines for lateral load resistance for GFRP-reinforced walls are available in codes. The ultimate limit state was addressed by providing strength capacity that limit ductility demand to their safe flexural displacement capacity. The strength demands were derived from ground motion spectra using modification factors that depend on both the strength and energy absorption of the structure. Deformation capacity was derived by proposing new definitions for elastic (virtual yield) displacement and maximum allowable displacement. Strength modification factor was proposed based on the test results. The occurrence of "virtual plastic hinge" for GFRP-reinforced shear walls was described providing new definitions convenient with the behavior of the GFRP-reinforced shear walls. "Virtual plastic hinge" length was estimated based on observations and calculations. Subsequently, the experimental results were used to justify the proposed design procedure. The promising results could provide impetus for constructing shear walls reinforced with GFRP bars and constitute a step toward using GFRP reinforcement in such lateral-resisting systems.

Efficient road network and connectivity play vital role in the development of any country. Majority of the rural roads are unpaved and connectivity of rural roads is always a major challenge. Unpaved roads are also used for temporary transportation facilities like access roads, haul roads for mines, forest roads and parking lots. Since these roads do not have asphalt surfacing, they are subjected to early failures due to distresses like rutting, pot holes and depressions . Stabilization of unpaved roads using geosynthetics has been proved to be promising in increasing the lifespan of these roads because they facilitate economical, aesthetic and effective design of the roads. Inclusion of geosynthetic layers at the interface of subgrade soil and granular sub-base, reduces the surface heave, ensures a better stress distribution and reduces the stresses transferred to the subgrade soil, as demonstrated by earlier researchers. Wide variety of geosynthetics like woven and nonwoven geotextiles, uniaxial and biaxial geogrids and geocells are used as reinforcement in road sections. Geotextiles improve the strength by interfacial friction, lateral restraint and membrane effect. Geogrids provide additional benefit of interlocking. Geocells are honeycomb shaped geosynthetic cellular confining systems filled with aggregates in which the reinforcement action is derived not only by friction and interlocking, but also by confinement. Load-deformation characteristics of reinforced soil-aggregate systems under static, repeated and cyclic loads is a potential topic of interest considering the fact that the design of geosynthetic reinforced unpaved roads is still under development and experimentation. The objective of the present study is to understand the beneficial use of geosynthetics in unpaved roads and to provide clear insight into the influence of geosynthetics on the cyclic loading characteristics of unpaved roads through laboratory experiments. California Bearing Ratio (CBR) tests were carried out on unreinforced and reinforced soil-aggregate systems to study the effect of various parameters such as type of reinforcement, form of reinforcement, quantity of reinforcement, and water content of the subgrade soil on the load-penetration response of the various systems. Modified CBR tests were also carried out to understand the influence of boundary of the mould and anchorage of reinforcement on the behavior of reinforced soil-aggregate systems. Behavior of unreinforced and reinforced soil-aggregate systems under repeated and cyclic loading is also studied to understand the resilience of the composite systems. From the measured stress-strain response, the elastic and plastic strains developed in various systems are compared. Different moduli such as secant modulus, cyclic modulus and resilient modulus are computed for different systems and compared. To investigate the effectiveness of geosynthetics in improving the load - bearing capacity, repeated load tests were carried out on model sections of unpaved road constructed in a steel test tank of size 750 mm × 750 mm × 620 mm. The effect of various parameters like the form of reinforcement, quantity of reinforcement, height of geocell layer and the position of geocell layer on the load-deformation behaviour of the unpaved model road sections was studied. Static and cyclic triaxial tests were carried out on unreinforced and reinforced granular sub-base materials to understand their stress strain behavior under static and cyclic loading conditions. The influence of quantity and form of reinforcement on the stress-strain behaviour of these materials was studied. From the studies it is observed that the use of reinforcement increases the CBR value of the soil-aggregate systems. Studies with two different sizes of CBR moulds indicated that the boundary effect in the standard CBR mould leads to the overestimation of the CBR value, resulting in unconservative design of road sections. Providing anchorage to the reinforcement in CBR tests did not produce an appreciable change in the load-penetration behavior. From the repeated load tests it was observed that the reinforced systems did not show any improvement in the load-deformation behaviour at low levels of rut depth. At higher rut depths, the reinforced systems developed less plastic settlements and more elastic settlements and low resilient modulus compared to unreinforced systems. From the model tests on unpaved road sections, it was observed that the improvement in the cyclic load resistance of the road due to the inclusion of geocell layer depends on the height of the geocell layer and its position. Increasing the height of geocell layer resulted in improved performance up to certain height of the geocell layer, beyond which, further increase in the height reduced the load resistance because of the inadequate granular overlay thickness and inadequate compaction of aggregate within the geocell pockets. Static and cyclic triaxial tests showed that the geogrid and geocell reinforced granular sub-base material sustained higher peak stresses and exhibited increase in modulus compared to the unreinforced specimens. Results of element and model tests carried out in this study gave important insight into the load-deformation characteristics of reinforced soil-aggregate systems under static, repeated and dynamic loads. The results provide guidelines regarding the selection of type, quantity and configuration of geosynthetic reinforcement while designing unpaved roads and the expected performance of these reinforced unpaved roads.