Recently completed experimental series
1-dof systems lying on square foundation : Monotonic and cyclic loading (P2011SQF2)
Experimental investigation of the metaplastic response of 1-dof systems on surface square foundations, subjected to displacement control lateral pushover loading. The objective of this series of experiments was to shed light on some of the most important factors that affect the non-linear response of shallow foundation-structure systems when loaded well into their non-linear range. Primarily, this parametric investigation was conducted with respect to the design FSv values, accomplished both by altering the superstructure mass and by utilizing different soil profiles. Secondly, the role of the sand relative density was examined by utilizing three cohesionless soil deposits. Moreover, the effect of the load history was investigated in terms of horizontal displacement amplitude and number of cycles. Finally, the potential effectiveness of shallow soil improvement was explored in an attempt to limit the uncertainties relating to the nonlinear soil response.
The experiments were conducted in the framework of the Research Project “DARE” (“Soil – Foundation – Structure Systems Beyond Conventional Seismic Failure Thresholds : Application to New or Existing Structures and Monuments”) and were carried out by Dr. I. Anastasopoulos, P. Kokkali, A. Tsatsis and E. Papadopoulos. The complete series of experiments consists of 34 experiments conducted between 07/04/2011 and 30/05/2011.
Experimental investigation of vertical load capacity of surface footings (P2011SQF1)
The primary objective of this project is the experimental measurement of the vertical load capacity of surface square footings, lying on different types of homogeneous and two layered sand profiles. Measuring the ultimate load capacity is the first step for the definition of the factor of safety against vertical loading, a key response parameter in many problems that will be explored in future projects. To this end, the footings are subjected to displacement control vertical pushover loading, in order to estimate their vertical load capacity. Cyclic vertical loading is also imposed at the footings in an attempt to capture their loading – unloading – reloading response. The experiments were conducted in the framework of the Research Project “DARE” (“Soil – Foundation – Structure Systems Beyond Conventional Seismic Failure Thresholds : Application to New or Existing Structures and Monuments”) and were carried out by Dr. I. Anastasopoulos, Dr. V. Drosos, P. Kokkali and A. Tsatsis. The complete series of experiments consists of 21 experiments conducted between 25/01/2011 and 11/03/2011.
Experimental investigation of the seismic behavior of classical multi-drum columns (S2011MDC)
One of the most common types of ancient monuments around the Mediterranean is the Greek classical temple. Unfortunately, since then, very few of them have remained intact and most of these monuments now consist of a couple of free-standing multi-drum columns. However, their dynamic response is highly non-linear and extremely complicated to be predicted by analytical methods. Since these structures are made of stones resting on top of each other without mortar and due to their extreme slenderness, multi-drum columns are particularly vulnerable to seismic shaking. A series of experiments on the shaking table of the Soil Mechanics Laboratory of NTUA was conducted to investigate the dynamic response of single or two “connected” multi-drum columns (portal). Results provide valuable insight on the different aspects of response taking place for different characteristics of the base excitation.
Experimental assessment of the seismic response of three-leaf stone masonry walls, with due consideration to soil–structure interaction (P2011SMW)
The out-of-plane seismic response of historic stone masonry walls is investigated herein, with due consideration to soil–foundation–structure interaction (SFSI). A series of pushover tests were performed on reduced scale (1:3) wall specimens, which consisted of a three-leaf stone masonry built on top of a spread footing. The walls were subjected to out-of-plane displacement, imposed at mid-height. Initially, a set of experiments were conducted ignoring SFSI. Then, the specimens were founded on a sand layer to examine the role of SFSI. Two idealized soil deposits were modeled: (a) dense sand of relative density Dr = 92%, and (b) loose sand of relative density Dr = 33%. It is shown that the performance of the walls is substantially affected by SFSI effects, as well as by the boundary conditions.
Experimental series currently in progress
1-dof systems lying on square foundation : Shaking Table Testing (S2011SQF1)
As a measure of limiting the uncertainties related with the foundation design, as well as enhancing the performance of soil–foundation–structure system, the employment of a shallow soil crust is suggested. Motivated by this innovative idea, an experimental study has been conducted at the Laboratory of Soil Mechanics of NTUA in order to investigate the effectiveness of such a measure. To that end, two idealized 1-dof structures founded on square footing are being subjected to dynamic loading (employing both artificial and seismic excitation real records of varying intensity), while emphasis is placed on the performance of the system when loaded well into its nonlinear range (seismic excitation exceeding the design limits).
The experiments were conducted in the framework of the Research Project “DARE” (“Soil – Foundation – Structure Systems Beyond Conventional Seismic Failure Thresholds : Application to New or Existing Structures and Monuments”) and were carried out by Dr. I. Anastasopoulos, P. Kokkali and A. Tsatsis. The complete series of experiments consists of 18 experiments conducted between 17/06/2011 and 18/07/2011.