ABSTRACT: This paper presents the work developed to design a shaking-table test at the EUCENTRE Lab, for the evaluation of the maximum capacity of a 3-storey building subjected to earthquake loading. The structural system of the building is composed of cast-in-situ sandwich squat reinforced concrete walls using polystyrene as a support for the concrete. The purpose of this test is to verify the dynamic behavior of this structural typology under earthquake acceleration. Previous to the shakeing-table tests carried out at the EUCENTRE Lab, extensive analytical and numerical research was developed on a set of models of the building under seismic input. Also, experimental tests were performed on single r.c. panels subjected to pseudo-static cyclic loading. The structural specimen was a structural system composed of cast-in-situ squat sandwich concrete walls characterized by 5.50 × 4.10 m in plan and 8.25 m in height. The input for the simulation was the Montenegro earthquake of April 1979. The construction of this building was developed outside the laboratory; it was lifted and pulled inside using hydraulic jacks and a roller system.
A bracing system was developed to assure the integrity of the structure during the transportation process.
ABSTRACT: This research aims at obtaining an experimental evaluation of the seismic response of structural systems composed of cast in situ squat concrete walls. Such structural systems are widely used for construction in non seismic areas and appreciated for their (i) limited constructions costs, (ii) limited installation times, (iii) great constructions flexibility and (iv) high energy and acoustic efficiency.
The study of the seismic behavior of structural systems composed of cast in situ squat concrete walls has been developed only recently and lies mainly in the study of the behaviour of the single squat wall panel under cyclic lateral loading.
In recent years, the seismic behaviour of cast in situ squat concrete walls has been the object of few scientific research works. In particular, most of these works focus on the study of the in-plane behavior of single cast in situ squat concrete wall under increasing horizontal loading cycles. Such researches have shown that cast in situ squat concrete walls have optimum (better than that of frame systems) characteristics both in terms of (i) strength resources towards horizontal loads and (ii) ductility capabilities.The assessment of the seismic behavior and performances of such a structural system (which is intrinsically characterized by superior resistance to horizontal loads, as compared to the more common frame systems) may lead to changes/modifications in the way the common 4-5 storey high buildings (for European countries) are constructed in seismic areas.
ABSTRACT: Structural systems composed of cast in place sandwich squat concrete walls, which make use of a lightweight material (for example polystyrene) as a support for the concrete, are widely used for construction in non seismic areas or in areas of low seismicity, and appreciated for their limited constructions costs, limited installation times, great constructions flexibility and high energy and acoustic efficiency.
If these cast-in-place squat concrete walls are assembled with appropriate connections, a cellular/box behavior of the structural system is obtained which leads to high strength resources (which allows not to use the post-elastic behavior and the ductility resources) and high torsional stiffness.
In recent years, from an exhaustive experimental campaign it has been possible to obtain the structural performances of single panels composed of cast-in-place sandwich squat concrete walls. A series of shaking table tests have been carried out at the EUCENTRE in Pavia.
The structural specimen which has been tested is a full-scale 3- storey structural system composed of cast-in-place squat sandwich concrete walls, characterized by 5.50 x 4.10 meters in plan and 8.25 meters in height.
ABSTRACT: Low reinforced thin concrete panels have been used for the re-construction of living buildings in the devastated zone of L’Aquila. A structural characterization of these types of panels is presented in this paper, paying particular attention to the fact that these panels are subjected mainly to shear forces.
Refined compression-field theory (RCFT) has recently been proposed in order to better predict the behaviour of reinforced concrete members subjected to in-plane shear and axial stresses.
This theory is based on continuum mechanics, i.e. satisfying compatibility, equilibrium and formulating the constitutive equations in terms of average (i.e. “smeared”) stresses and strains.
The improvement of RCFT in comparison with the two most famous theories for reinforced concrete member subjected to shear [i.e. the modified compression-field theory (MCFT), and the rotating-angle softened-truss model (RA-STM)], deals with an embedded bar model based on the tension stiffening model in concrete.
The preliminary numerical validations seem very promising. However, additional experimental data are required for calibrating and validating the parameters of the proposed RCFT theory.
ABSTRACT: Structural systems composed of cast in situ sandwich squat concrete walls, which make use of a lightweight material (for example polystyrene) as a support for the concrete, are widely used for construction in non seismic areas or in areas of low seismicity, and appreciated for their limited constructions costs, limited installation times, great constructions flexibility and high energy and acoustic efficiency. However their seismic behaviour has not been fully investigated.
In recent years, an exhaustive experimental campaign, carried out by the University of Bologna and the Eucentre labs in Pavia, was devoted to the assessment of the seismic performances of single walls and of a portion of structure through cyclic tests under horizontal loads.
To validate the theoretically and partially-experimentally anticipated (through cyclic tests under horizontal loads) good seismic behaviour of cellular structures composed of cast in situ squat sandwich concrete walls, shaking table tests were performed, at the laboratory facilities of the Eucentre in Pavia, on a full-scale 3-storey structural system composed of cast-in-situ squat sandwich concrete walls (characterized by 5.50 x 4.10 meters in plan and 8.25 meters in height).
ABSTRACT: In recent years, the seismic behaviour of reinforced concrete bearing panels structures has been the object of several research works.
This paper presents a summary of the results obtained in a wide experimental/analytical/numerical correlation campaign carried out as a joint effort between the University of Bologna and the EUCENTRE labs in Pavia.
This effort was devoted at the assessment of the seismic performances of structures composed of (lightly reinforced) concrete/polystyrene sandwich bearing panels.
In this paper: (1) the results of a number of pseudo-static tests with cyclic horizontal load have been briefly recalled; (2) extensive analytical developments have been carried out to evaluate the mechanical characteristics and the seismic behaviour of lightly reinforced concrete panels; (3) numerical results have been obtained with advanced analyses on a sophisticated model of the panel; (4) a comparison between the analytical, the numerical and the experimental results has been performed.
ABSTRACT: The research described in this paper investigates the seismic behaviour of lightly reinforced concrete bearing sandwich panels, heavily conditioned by shear deformation. A numerical model has been prepared, within an open source finite element (FE) platform, to simulate the experimental response of this emerging structural system, whose squat-type geometry affects performance and failure mode.
A calibration of this equivalent mechanical model, consisting of a group of regularly spaced vertical elements
in combination with a layer of nonlinear springs, which represent the cyclic behaviour of concrete and steel,
has been conducted by means of a series of pseudo-static cyclic tests performed on single full-scale
prototypes with or without openings.
Both cantilevered and fixed-end shear walls have been analyzed.
ABSTRACT: Insulating concrete forms (ICF) have become increasingly common in commercial projects. In ICF wall construction, wall sections are built by stacking blocks atop each other prior to pouring concrete. A block consists of two foam panels with a cavity between connected by plastic webbing. ICF wall construction has several advantages over traditional assemblies of CMU and stick-frame walls, including: improved structural performance (demonstrated by wind projectile tests, ICF homes surviving hurricanes, and preliminary blast testing), energy efficiency, and speed of construction. STALA® integrated framing assemblies (IFA) were developed by STALA® Integrated Assemblies, LLC to streamline framing of openings in ICF wall construction. The IFAs act as the opening formwork and reinforcement. Protection Engineering Consultants (PEC) and STALA® performed an analytical study to evaluate IFAs used to frame ICF wall, door and window openings subjected to blast loads. The main goal was to develop design guidance for ICF walls with IFAs for Department of Defense (DoD) loads while meeting the DoD low level of protection (LLOP) response criteria (UFC 04-010-01). PEC developed a non-composite resistance function for each ICF wall and IFA combination for use in single-degree-of- freedom (SDOF) analysis program, specifically SBEDS v4.0. Design tables were constructed for DoD charge weights and standoffs based on the results of the SDOF analyses. The design tables illustrate how IFAs impact ICF wall blast performance as a function of opening width and clear spacing. In general, IFAs improve the performance of the typical ICF wall, such that all cases analyzed meet the DoD LLOP response criteria when subjected to DoD charge weights at conventional construction standoffs. This paper presents a summary of our assumptions, analyses, results, and recommendations for future work.
ABSTRACT: The demand for green buildings construction is growing from commercial multi-story buildings to condominiums and single family houses. One of the emerging structural systems that addresses sustainability from the structural and construction point of view has been the insulated concrete form (ICF) grid walls, which are built using prefabricated stay-in-place forms that also provide improved thermal insulation over conventional methods, thereby reducing the energy requirements throughout the life of the building. The structural components of the ICF wall consist of horizontal and vertical reinforced concrete cores. From the engineering point of view and when compared to conventional construction, reduced environmental impact can be realized from lower consumption of traditional materials such as concrete and from lower generation of waste through the near elimination of formwork. The awareness and demographic propensity toward sustainability in urban areas can overlap with areas of significant seismic risk, creating a societal need for implementation despite the lack historical performance. The designers and suppliers are unsure of the path toward approval as this type of construction falls outside the applicability of current building code and limited guidance exist on the steps needed. This paper outlines the development of an experimental program aimed to investigate the seismic performance through full-scale cyclic tests. The preliminary force deformation results from a cyclically loaded ICF grid walls are outlined, where the overall behavior indicated that the system could potentially lead to successful implementation in areas of high seismicity.
ABSTRACT: Sustainable building materials offer energy efficiency and environmental performance. One possible sustainable building product is insulating concrete forms (ICF). An ICF wall section consists of expanded polystyrene and concrete with polyethylene ties. One difference between a “normal” construction and ICF construction is that the forms stay in place after concrete has cured. The forms and concrete act as insulation material and have the potential for reducing energy consumption in buildings. The goal of this research is to conduct a comparative life cycle assessment (LCA) of the wall sections comprised of ICF and traditional wood-framed for the life cycle phases of raw materials, manufacturing, construction, use and end of life. Preliminary results comparing ICF and wood frame in the manufacturing phase for above grade construction are presented. To investigate the use phase, an energy modeling tool eQuest will be utilized, along with discussing the development of the LCA residential model.