# Dynamic Properties of Calcareous Sands from Urban Areas of Abu Dhabi
## 1 Introduction  
Abu Dhabi (ABD) in the United Arab Emirates (UAE) has recently developed a national building code [1] to support the significant growth in the construction sector. The code mandates dynamic analysis of structures under seismic loading, which requires the dynamic properties of subsurface material as a function of shear strain level among other geotechnical properties. The behavior of dynamic properties of soils such as the shear modulus (G) and the damping ratio (D) at different shear strain levels are typically obtained from laboratory tests. Since the Cambrian age, the region of ABD has primarily consisted of sediments deposited mostly from Tertiary rocks of a shallow shelf environment (carbonate platform). Recent sediment deposits in and around ABD are rich in carbonate minerals with varying amounts of gypsum and seashells. The reclaimed areas along the shores of ABD are also constructed with dredging and hydraulic fills of calcareous sands from the Arabian Gulf ([PERSON] [2]). The dynamic characterization of these soils is expected to be significantly different not only from siliceous sands but also from calcareous sands of other regions.  
Several studies have evaluated the dynamic properties for silica sands with bender element (BE), cyclic triaxial (CT) and resonant column (RC) tests (e.g., [PERSON] et al. [3]; [PERSON] et al. [4]; [PERSON] et al. [5]; [PERSON] et al. [6]). Similarly, several studies are availablefor reconstituted samples of calcareous sands found in geographical regions other than ABD ([PERSON] and [PERSON] [7]; [PERSON] et al. [8]; [PERSON] et al. [9]; [PERSON] et al. [10]; [PERSON] et al. [11]). One study evaluated the dynamic properties of reconstituted samples of naturally occurring calcareous sands of ABD ([PERSON] et al. [12]); however, it did not evaluate the dynamic properties as a function of shear strain. Similarly, [PERSON] et al. [13] also tested reconstituted samples obtained from a hydraulic fill of an island close to ABD. The designers in ABD typically rely on degradation models of dynamic properties that are not representative of regional soils for the purpose of site response analysis. The focus of this study is to evaluate the dynamic properties of in situ undisturbed calcareous sands of ABD as a function of shear strain level and to present the results in the form of standard hyperbolic models for dynamic analyses. Undisturbed specimens of calcareous sands are collected from different zones of urban ABD. The dynamic properties are evaluated at different confinements and shear strain levels in cyclic triaxial (CT) devices fitted with bender elements (BE). The low strain Vs is obtained from bender element (BE) tests. The results are fitted with hyperbolic models ([PERSON] and [PERSON] [14]) and then compared with selected studies on calcareous and siliceous sands from the literature.  
The results indicate that sands from urban areas of ABD degrade less than calcareous sands of other regions mainly because of reconstitution of the sands in those studies that can damage the effective inter-particle cement. The variation of Vs with confinement shows large variability among the tested sands in the present study, and it is therefore recommended to evaluate low-strain properties on a case-by-case basis. The degradation behavior of the tested sands appears to be unaffected by the source or location of the material within ABD. The presented hyperbolic models can therefore be used for site response analysis or soil structure analysis as mandated by the national building code of ABD.