Infill Model Research Articles

Numerical modelling of the cyclic behavior of timber-framed structures

The present paper presents a study on the applicability of numerical models in predicting the global response of timber-framed shear walls during earthquake events. Based on previous in-plane cyclic testing of traditional timber frames with and without masonry infill, numerical models were developed to describe the cyclic response of traditional timber frame walls including flexural behavior, pinching and strength degradation. The numerical models were developed in the finite element software OpenSees with calibrated springs representing nailed connectors found in traditional half lap joints. Based on the calibrated models a study was conducted on the timber frame wall with brick infill model by varying wall configuration and analysing cumulative energy dissipation and the effect of slenderness and load capacity with increasing drift. A good correspondence was obtained with the experimental data and future work will include the application of the model to whole buildings.

Empirical‐based out‐of‐plane URM infill wall model accounting for the interaction with in‐plane demand

SummaryThe role of masonry infills in the seismic behavior of reinforced concrete buildings has been widely studied in terms of their strength and stiffness contribution in the in‐plane (IP) direction, while fewer studies have been carried out on their response and modeling in the out‐of‐plane (OOP) direction. In this paper, the state of the art in code and literature provisions regarding infills' OOP capacity and seismic demand is presented, together with a review of the experimental tests that have been carried out to investigate infills' OOP behavior and the effects of IP‐OOP interaction. This review aims to collect an experimental database that is used to evaluate the effectiveness of literature and code provisions and to propose a semiempirical approach both for predicting infills' OOP strength, stiffness, and displacement capacity and for modeling the effects of IP displacement demand on OOP behavior and vice versa. Then, the state of the art on modeling of infills' OOP behavior and IP‐OOP interaction is presented together with a new macro model based on the proposed formulations and conceived to represent the IP and OOP behavior by taking into account the mutual interaction effects. Finally, the proposed model is used for an example application on two case‐study buildings, showing the effects of taking into account or neglecting the IP‐OOP interaction phenomena.

RESPON SEISMIK STRUKTUR RANGKA DINDING PENGISI YANG DIMODEL DENGAN ELEMEN SHELL PENUH DAN PARSIAL

Abstract: Research on the seismic response of in-filled frame structure has been done with in-filled frame model as full and partial shell elements. The wall is considered active until the maximum load on the full shell models, while the partial shell model using the gradual load with the strength of the wall is considered inactive if the stress of the wall exceeded the wall strength The 4 storey hotel building with full wall in x-direction and wall with opening in y-direction were modeled in SAP 2000 as 3D infilled-frame using full and partial shell element. In Mxy models, both wall were included in the model, while in My models, only the wall in y-direction included. Therefore, 4 models were obtained, there are full shell model MxyShPn and MyShPn and partial shell model MyShPar and MyShPar. In addition, 2 diagonal strut models MxyS and MyS and an open frame model MOF were made as comparison. Prior to model 3D structure, validation models were created using test result condited by other as reference. For that purphose 5 2D models were created there are open frame model MOF, single strut model MST, multiple strut model MSG, full shell model MShPn and partial shell model MShPar. From validation models, it is apparent that the MxyShPar model mimic the behavior of tested structure better than the other models. From the 3D models analysis result show that the displacement in x-direction of MxyShPn, MxyShPar, MxyS were 89%, 85%, 84% smaller than those of MOF, respectively inclusion of wall in the models, also reduce the internal forces and reduse the natural period of the sctructure.

RESPON SEISMIK STRUKTUR RANGKA DINDING PENGISI YANG DIMODEL DENGAN ELEMEN SHELL PENUH DAN PARSIAL

Abstract: Research on the seismic response of in-filled frame structure has been done with in-filled frame model as full and partial shell elements. The wall is considered active until the maximum load on the full shell models, while the partial shell model using the gradual load with the strength of the wall is considered inactive if the stress of the wall exceeded the wall strength The 4 storey hotel building with full wall in x-direction and wall with opening in y-direction were modeled in SAP 2000 as 3D infilled-frame using full and partial shell element. In Mxy models, both wall were included in the model, while in My models, only the wall in y-direction included. Therefore, 4 models were obtained, there are full shell model MxyShPn and MyShPn and partial shell model MyShPar and MyShPar. In addition, 2 diagonal strut models MxyS and MyS and an open frame model MOF were made as comparison. Prior to model 3D structure, validation models were created using test result condited by other as reference. For that purphose 5 2D models were created there are open frame model MOF, single strut model MST, multiple strut model MSG, full shell model MShPn and partial shell model MShPar. From validation models, it is apparent that the MxyShPar model mimic the behavior of tested structure better than the other models. From the 3D models analysis result show that the displacement in x-direction of MxyShPn, MxyShPar, MxyS were 89%, 85%, 84% smaller than those of MOF, respectively inclusion of wall in the models, also reduce the internal forces and reduse the natural period of the sctructure.

Using UAV acquired photography and structure from motion techniques for studying glacier landforms: application to the glacial flutes at Isfallsglaciären

AbstractGlacier and ice sheet retreat exposes freshly deglaciated terrain which often contains small‐scale fragile geomorphological features which could provide insight into subglacial or submarginal processes. Subaerial exposure results in potentially rapid landscape modification or even disappearance of the minor‐relief landforms as wind, weather, water and vegetation impact on the newly exposed surface. Ongoing retreat of many ice masses means there is a growing opportunity to obtain high resolution geospatial data from glacier forelands to aid in the understanding of recent subglacial and submarginal processes. Here we used an unmanned aerial vehicle to capture close‐range aerial photography of the foreland of Isfallsglaciären, a small polythermal glacier situated in Swedish Lapland. An orthophoto and a digital elevation model with ~2 cm horizontal resolution were created from this photography using structure from motion software. These geospatial data was used to create a geomorphological map of the foreland, documenting moraines, fans, channels and flutes. The unprecedented resolution of the data enabled us to derive morphological metrics (length, width and relief) of the smallest flutes, which is not possible with other data products normally used for glacial landform metrics mapping. The map and flute metrics compare well with previous studies, highlighting the potential of this technique for rapidly documenting glacier foreland geomorphology at an unprecedented scale and resolution. The vast majority of flutes were found to have an associated stoss‐side boulder, with the remainder having a likely explanation for boulder absence (burial or erosion). Furthermore, the size of this boulder was found to strongly correlate with the width and relief of the lee‐side flute. This is consistent with the lee‐side cavity infill model of flute formation. Whether this model is applicable to all flutes, or multiple mechanisms are required, awaits further study. © 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Theoretical analysis of a row of piles as passive barriers and an equivalent in-filled trench model

A theoretical study on the ground vibration isolation efficiency by a row of piles as passive barrier in a three-dimensional context was presented. The analysis was accomplished with the aid of integral equations governing Rayleigh wave scattering, used to predict the complicated Rayleigh wave field generated by a number of irregular scatters embedded in an elastic half-space. Then, the passive isolation effectiveness of a row of piles for screening Rayleigh wave was studied in detail. The effects of relevant parameters on the screening effectiveness were investigated and analyzed from the perspective of equivalence with in-filled trench. The results show that using a row of rigid piles as wave barrier is more effective than that of flexible ones, and an optimum reduction of vibration can be achieved either by increasing the size of piles or by decreasing the net spacing between the piles. Finally, based on the derived integral equation for Rayleigh wave scattering, the principle of equivalent modeling of the barrier of piles by an in-filled trench is put forward, which simplifies the analysis of vibration isolation by a row of piles.

Effects of the yield and ultimate strengths of the equivalent strut models on the response of existing buildings with infill panels

The modelling of infilled frames is generally very difficult because of the several parameters influencing their response. Specifically, the macro-models have many uncertainties related to the definition of the Equivalent Rod that simulates the panel. Main parameters involved in the definition of the Equivalent Strut Models (the width of the strut, the constitutive Force-Displacement law of the panel and the number of struts adopted to simulate the panel) induce a great variability of the structural global response. Consequently, the quantification of the uncertainties that influence the building safety verification becomes very important. In order to investigate this issue, three examples of buildings were developed and the characteristic points of the nonlinear law of the struts (yield and maximum strength) were changed within a range of allowable values. The objective is to appraise the sensitivity of the structural capacity (in terms of displacement) of infill models.

Eurocode-based seismic assessment of modern heritage RC structures: The case of the Tower of the Nations in Naples (Italy)

Given the interest earned recently by modern heritage structures, seismic assessment criteria of Eurocode 8 for ordinary reinforced concrete structures are applied to a modern heritage RC building. This case study, the Tower of the Nations in Naples, was designed at the end of 1930s. Modal dynamic identification, in situ inspections and testing provided the necessary knowledge of the structure in terms of geometry, structural details, and material properties. Two nonlinear models of the structure are built up in both the hypotheses of accounting and not accounting for tuff infills’ stiffness and strength contribution. Lumped plasticity model for reinforced concrete elements and equivalent strut macro-models for tuff and concrete infills are employed. Seismic assessment through nonlinear dynamic analyses is carried out for both limit states of Significant Damage and Damage Limitation. Assessment of bare and infilled models emphasizes a lower demand in terms of maximum interstorey drift of the infilled model with respect to the bare model, for both limit states considered. Record-to-record variability for the sets of seven records becomes larger if infills strength and stiffness contribution is taken into account. Outcome of the assessment is not affected by infills, i.e. the structure can be considered safe (according to EC8 provisions) for both limit states, and in both modeling hypotheses. On the other hand, the ratio demand over capacity, for both the limit states considered, is strictly influenced by infills’ contribution. Assessment tools provided for ordinary RC structures can be addressed to modern heritage buildings as shown in this case study, even if specific care is necessary for nonlinear structural modeling in case of non-conventional structural elements and non-conventional structural materials (e.g., tuff infills in lieu of clay hollow brick infills).

Combining in-plane and out-of-plane behaviour of masonry infills in the seismic analysis of RC buildings

Current seismic codes (e.g. the NTC08 Italian code and the EC8 European code) adopt a performance-based approach for both the design of new buildings and the assessment of existing ones. Different limit states are considered by verifying structural members as well as non structural elements and facilities which have generally been neglected in practice. The key role of non structural elements on building performance has been shown by recent earthquakes (e.g. L'Aquila 2009) where, due to the extensive damage suffered by infills, partitions and ceilings, a lot of private and public buildings became unusable with consequent significant socio-economic effects. Furthermore, the collapse of infill panels, particularly in the case of out-of-plane failure, represented a serious source of risk to life safety. This paper puts forward an infill model capable of accounting for the effects arising from prior in-plane damage on the out-of-plane capacity of infill panels. It permits an assessment of the seismic performance of existing RC buildings with reference to both structural and non structural elements, as well as of their mutual interaction. The model is applied to a building type with RC framed structure designed only to vertical loads and representative of typical Italian buildings. The influence of infill on building performance and the role of the out-of-plane response on structural response are also discussed.

Influence of Masonry Infill on the Dynamic Characteristics of RC Frames on Slope Part (I): Background and the Infill Model

Buildings on the slope are widely used and have been increasing in mountainous city. The object of this study is to study the influence of masonry infill on the seismic characteristics of RC frames on slope. The concept of slope building is introduced, and the proposed infill model is presented. It is a single equivalent strut model with the compression and tension behavior. The proposed infill model uses the energy-based cyclic degradation law to simulate the deterioration of the infill during the seismic action. In the Part (II) of the paper, the infill model is calibrated, and the performance of different reinforced concrete two bay-frames, bare and infilled, subjected to eight seismic motions was investigated.

Influence of Masonry Infill on the Dynamic Characteristics of RC Frames on Slope, Part (II): Seismic Performance

Slope structure means a structure built on a slope in the mountainous region. The aim of this study is to study the influence of masonry infill on the seismic characteristics of RC frames on slope. First, the main results of the calibration analyses using the infill model introduced in the Part (I) of the paper are presented. Second, the performance of different reinforced concrete two bay-frames, bare and infilled, subjected to eight seismic motions were investigated. The results show that if the infill is built correctly in all storeys, it gives a significant contribution to the energy dissipation capacity by reducing the dissipation energy demands in frame elements and decreasing significantly the maximum displacements. Therefore the contribution of masonry is of great importance.

The Study on Infilled Walls Effect in RC Frame Infilled Wall Structure

The seismic damage and even collapse of the infilled walls in RC frame infilled wall structure is the issue that needs thorough study, In this paper, firstly introduces the improved infilled wall model which can consider the interaction of in-plane and out-of-plane, and can judge the damage state of infilled walls, as well as the interaction between RC frame and infilled walls. Then, based on the finite element software OpenSees, under rare earthquake, performed the nonlinear numerical simulation of two finite element models-RC frame without infilled walls and RC frame with infilled walls, comparative analysis differences of both plastic hinge zone’s steel strain, drift and acceleration response, and in-depth study of the infilled walls effect in RC frame infilled wall structure and reason analysis.

Implementation and Verification of a Masonry Infill Model Considering the Out-Of-Plane Behaviour

The response of reinforced concrete buildings to earthquake loads can be substantially affected by the influence of infill walls. Also the out-of-plane failure of the infill can cause heavy casualties. In this article, an improved numerical model for the simulation of the in-plane and out-of-plane behaviour of masonry infill is proposed. First, the proposed model is presented. This is an upgrading equivalent strut model composed of two beam-column type elements, with a node at the mid-span assigned a mass in the in-plane and the out-of-plane direction to account for the inertial forces in both directions. Second, the main results of the calibration analyses obtained with two experiments are presented and discussed.

Modeling of URM Infills and Their Effect on Seismic Behavior of RC Frame Buildings

Un-reinforced Masonry (URM) infilled Reinforced Concrete (RC) frames are the most common structural sys- tem for multi-storey buildings in India and many other parts of the world. The infills are known to change the behavior and failure pattern of the infilled frames under lateral loading significantly, due to infill-frame interaction. The behavior is further affected by the construction sequence of infilled frames, as the infills are usually added after completion of the frame, and it results in a gap between the infill and soffit of the beam above. This paper presents a macro model for URM infilled frames to simulate the gap and can be implemented on available software. Using the developed model, an analyti- cal study on effect of infills and their construction sequence, on the seismic performance of RC frame buildings designed as per relevant Indian Standards is presented. The infills are modeled as diagonal struts, with stiffness as defined in ASCE 41 and strength in various modes of failure is considered. Nonlinear 'Gap' elements are used to simulate the gap between the infill and the beam and a sequential analysis is performed to take into account the construction sequence of infill pan- els relative to frames.

Preliminary analysis of a soft‐storey mechanism after the 2009 L'Aquila earthquake

AbstractObservation of damage caused by the recent Abruzzo earthquake on April 6th 2009 showed how local interaction between infills and RC structures can lead to soft‐storey mechanisms and brittle collapses. Results of the present case study are based on observed damage caused by the earthquake in the zone of Pettino. Analytical model based on simulated design procedure was built up and time history analyses were employed to verify the causes of the structural collapse, as highlighted by observed damage. This failure mechanism was investigated taking into consideration all components of the ground motion. Nonlinear behavior of brick masonry infills was taken into account and two parametric hypotheses for infill mechanical properties were considered, given the uncertainties that typically characterize these nonstructural elements. Nonlinear modeling of infills was made by a three‐strut macro‐model aimed at considering both local and global interaction between RC frame and infills. Seismic input was characterized by the real signal registered during the mainshock near the case‐study structure. Different shear capacity models were considered in the assessment.Analytical results seem to confirm with good approximation the likely collapse scenario that damage observation highlighted; the lack of proper detailing in the columns made the local interaction between infills and RC columns and the strong vertical component of the ground motion to be the main causes of the brittle failure. Copyright © 2010 John Wiley & Sons, Ltd.

Correlating Permo-Carboniferous sandstones with biogenic silica microfossils: a new biostratigraphic tool for the E&P industry

Globally, significant oil and gas reserves occur in so-called ‘barren red beds’. These sediments are generally deposited in a shallow to non-marine environment under arid (desert) climate conditions. In terrestrial basins, biostratigraphic analysis of plant microfossils (pollen and spores) is often effective in constraining static geological models. Unfortunately, such organic-walled microfossils are not preserved in red bed deposits due to oxidation, hampering stratigraphic correlation on both local (field) and regional scale. Although red beds occur throughout the geological timescale, examples with an economic interest are the Late Carboniferous, Permian and Early Triassic of Europe (Barren Measures, Rotliegendes, Bunter − Doornenbal and Stevenson, 2010), the Triassic of the United States, and the Permo-Carboniferous of the Middle East (Melvin & Sprague, 2006). Here, for the first time, we apply biogenic silica microfossils as a stratigraphic tool in the Permo-Carboniferous red bed sequences in the Southern North Sea. The combination of their qualitative occurrence, cyclic abundance patterns, and stable isotopic data provides the possibility to improve existing regional geological correlations, position regional unconformities, and to refine reservoir architecture models. We have applied the biogenic silica stratigraphy in two representative case studies in the Upper Rotliegend in the Southern North Sea Basin. The first example focuses on refining the basin infill model of the Upper Rotliegend and the second on detecting the position of the Base Permian Unconformity (BPU). Both aspects are critical for E&P activities in the Southern North Sea but are notoriously difficult to determine due to a lack of effective correlation tools in the red bed deposits. Permo-Carboniferous red beds in

Transverse Resistance of Masonry Infills

In this paper, a confined infill panel previously experimented under out-of-plane loading is modeled and analyzed by the dynamic explicit method (DEM). This method is shown to have a good estimation of the experimental results, and is thus adopted to investigate the out-of-plane behavior of an infill model. Based on the analytical results, the stress distribution of an infill panel prior to and after cracking, and the effect of an arching mechanism on post-cracking behavior, is studied. A semi-empirical relationship is accordingly developed for predicting the transverse resistance of masonry infills due to one-way arching action, which accounts for the affects of the boundary frame stiffness, the masonry modulus of elasticity, and the infill slenderness ratio on the transverse strength. The theory also considers two distinct failure modes: boundary crushing and transverse instability. The relationship is shown to have good precision in predicting a large number of experimental results reported in the literature.

Analytical modeling of masonry infills with openings

In order to perform a step-by-step force-displacement response analysis or dynamic time-history analysis of large buildings with masonry infilled R/C frames, a continuous force-deformation model based on an equivalent strut approach is proposed for masonry infill panels containing openings. The model, which is applicable for degrading elements, can be implemented to replicate a wide range of monotonic force-displacement behaviour, resulting from different design and geometry, by varying the control parameters of the model. The control parameters of the proposed continuous model are determined using experimental data. The experimental program includes fifteen 1/3-scale, single-story, single-bay reinforced concrete frame specimens subjected to lateral cyclic loading. The parameters investigated include the shape, the size, the location of the opening and the infill compressive strength. The actual properties of the infill and henceforth the characteristics needed for the diagonal strut model are based on the assessment of its lateral resistance by the subtraction of the response of the bare frame from the response of the infilled frame.

Discussion of “Geology and diamond distribution of the 140/141 kimberlite, Fort à la Corne, central Saskatchewan, Canada”, by A. Berryman, B.H. Scott-Smith and B.C. Jellicoe (Lithos v. 76, p. 99–114)

A wide variety of geological data and geological observations by numerous geoscientists do not support a two-stage crater excavation and in-fill model, or a champagne glass-shaped geometry for the 169 or 140/141 kimberlite bodies in the Fort à la Corne kimberlite field, Saskatchewan as described by Berryman, A., Scott Smith, B.H., Jellicoe, B., (2004). Rather, these kimberlite bodies are best described as polygenetic kimberlite tephra cones and tuff rings with associated feeder vents of variable geometry as shown by previous workers for the 169 kimberlite, the 140/141 kimberlite and the Star kimberlite. The domal tephra cone geometry is preserved due to burial by conformable Cretaceous marine mudstones and siltstones and is not an artifact of Quaternary glacial processes.

Growth Faulting and Syntectonic Casting of the Dawson Creek Graben Complex: A North American Craton-Marginal Trough; Carboniferous-Permian Peace River Embayment, Western Canada

The Dawson Creek Graben Complex was a 150 {times} 300 km, craton-perpendicular trough near the western North American craton margin. Sedimentary infill spanned 100 million years, and this tectonically controlled basin provides a comparison with other craton-marginal troughs or aulacogens, such as the Big Snowy, Uinta, Delaware, and Southern Oklahoma. The authors suspect that the graben complex was controlled by outboard, Antler-like orogeny and perhaps some strike-slip control. This syntectonic graben infill model provides a basis for developing new structural-stratigraphic plays in this mature basin. This extensional trough rests on a former basement arch and is centered in the broadly downwarped Peace River embayment. Sediment infill records several graben casting stages beginning with westernmost down-dropping, which then extended eastward and was accompanied by an increase in growth-type block faulting. Subsidence and faulting decay was followed by a retreat to western areas and tectonic stabilization. The complex was an arcuate half-graben, steep to the north, that widened asymmetrically and increased in depth to the west through time. The complex contained a principal half-graben with neighboring satellite grabens; throughout the complex are numerous kilometer-scale horst and graben blocks. The horsts subsided slower than neighboring grabens. This differential subsidence along block-bounding syn- andmore » postdepositional growth-type normal faults controlled formation and bed thickness, as did inter- and intraformational unconformities.« less