No abstract

No abstract

Historical masonry structures are very important as they carry cultural heritage, so it is important to protect these structures from natural disasters such as earthquakes and transferred to the next generations. It is known that masonry structures are weak against earthquakes, therefore, a suitable analysis method for assessment and retrofitting purposes is a must. Generally, the fixed-base concept is used for analysis and design purposes, however, in reality, the structures are not fixed-base but they are resting on soils. The aim of this study is to make a comparison study between dynamic responses of fixed-base and soil-structure interaction (SSI) models for bridge masonry structures, the historical Dalal bridge was selected as the case study. First, the bridge was modeled as a fixed base model, and then three different soil profiles (hard, medium and soft soils) were added to the underneath of the structure. The numerical models were analyzed under Elcentro earthquake record. Results indicating a good agreement between the fixed base and the case of hard soil base. However, considerable differences were observed for medium and soft soil profiles.

This study investigates the results of the numerical analysis on effect of existing supported excavation on ultimate bearing capacity (qult) of strip footing adjacent to supported excavation in sandy soil. The influence of distance (L) between the foundation and the supported excavation was studied as well as the effect of the excavation depth (He). For this purpose, on a full-scale model, a series of numerical calculations were carried out to determine how (L) and (He) affected the behavior of strip foundation. Based on finite element approach, the computer software Plaxis 2D code was utilized. Non-linear hardening soil model, a sophisticated elastoplastic stressstrain constitutive soil model, was used to characterize sandy soil. Based on Mindlin's beam theory, the strip footing and sheet pile wall were identified as elastic beam components with significant flexural rigidity (EI) and axial stiffness (EA). The sheet pile was installed at three different distances (L) away from the face of the strip foundation 1B, 1.5B and 2B, where B is the width of foundation. For each distance, three different excavations (He) were used with dimensions 1B, 1.5B and 2B. The numerical outcomes show that the ultimate bearing capacity (qult) of shallow foundation is decreased when distance between strip foundation and supported excavation is decreased, and vice versa. Additionally, (qult) is reduced as the depth of excavation behind sheet pile wall is increased, and vice versa.

Improving the engineering properties of soils is one of the common necessity encountered in geotechnical engineering applications. This article investigates the effect of the addition of polypropylene fiber (PPF) on shear strength parameters of compacted sand. Different percentages of PPF (0.5%, 1.0% and 1.5%) by dry weight of the sand were added. Maximum dry density (MDD) and optimum moisture content (OMC) of sand alone and PPF-reinforced sand were measured by standard Proctor compaction test. Subsequently, shear box test was applied for sand and PPF-reinforced sand under three different normal stresses, samples were prepared under the condition of OMC and MDD. The results showed that when the percentage of PPF reaches 1%, the internal friction angle was at maximum value and cohesion is at the minimum value. With increasing percentage of PPF internal friction angle decreased and cohesion increased.