Experimental Deflection Research Articles

PREDICTION OF HIGH-PERFORMANCE FIBERREINFORCED POLYMER CONCRETE USING FUZZY NEURAL NETWORK PROTOTYPES

RC building elements of Reinforcing and upgrading is essential to extend its maintenance time, to overcome first structural limitations, and to control the consequence of building construction or design flaws. The RC constructions are reinforced by using the FRP-fiber reinforced polymer. This study utilizes the FRP in concrete structures for instance a Jute, coir, and Sisal is explored for its reliability in improving ductility and strength related structural performance. FRP structural response of the model parameters is studied by measuring the numerical and experimental terms, for instance, Ductility, Deflection, Tensile-Strength, and Compression-Strength. The quality of the sample specimens is tested by using the Fuzzy Neural Network (FNN) system. At this time, compared with existing jobs, the propounded Fuzzy Neural Network model accomplishes the best presentation regarding all boundaries for the fiberreinforced specimen over different stacked conditions

Nonlinear finite element study on element size effects in alkali-activated fly ash based reinforced geopolymer concrete beam

The practical application of geopolymer concrete structure is getting attention due to its environmentally friendly characteristics. This paper presents non-linear Finite Element Analysis (FEA) on the element size effect in reinforced geopolymer concrete beam. Element size significantly influences the failure mechanism of structure especially in ductile fracture of reinforced concrete. The critical failure strain, crack patterns and orientations are mesh sensitive in finite element analysis for reinforced concrete structure. The impact of the element size on behavioral aspects of reinforced geopolymer concrete beam such as the crack pattern, ultimate load capacity and load-displacement behavior studies discussed along with a formerly conducted experimental data. Further validation of FEA is carried out using the theoretical flexural strength of the beam according to Euro code 2. Results show that element size has a significant effect in capturing the cracking pattern of reinforced geopolymer concrete beam. FEA result from the positive principal strain contour confirms that the fine mesh size captured the tension, the diagonal shear and compression cracks, even the band of surrounding cracks around the bottom reinforcement, precisely as compared to coarse meshes. It has been observed that the utilization of fine mesh with 10 mm element size predicts the experimental and theoretical ultimate load by 99.46% and 96.11%, respectively. Coarse mesh having 25 mm element size shows slightly higher variation in predicting the experimental and theoretical ultimate load by 93.75% and 90.42%, respectively. In addition, fine mesh confirms the experimental mid-span vertical deflection by 99.44% however the coarse mesh predicts in significant deviation by estimating 48.04% of the experimental mid-span vertical deflection. Furthermore, the ductile failure of the beam was accurately traced by the fine mesh.

Resonance vibration interventions in the femur: Experimental-numerical modelling approaches

MotiveExternal vibration excitation might be key to many novel non-surgical interventions for pathologies in the musculoskeletal system and in other parts of the human organism. Lack of understanding about vibration patterns, their controllability, and reproducibility are three limitations of ongoing research. This study establishes a bovine vibration model and animal model replacements for future research. MethodsWe used biological samples (n=5) and one polyurethane sample of the bovine femur. Mechanical resonance was measured experimentally and analysed numerically by finite element method. Main resultsThe experiments obtained 5 distinct mode shapes for the biological sample set, with standard deviation < 7.5%. Finite element analysis of the biological samples can replicate experimental mode shape deflection. The use of polyurethane changes resonance character but results are also good approximations of the biological samples. ConclusionsA model of the bovine femur with consistent resonance behaviour is presented with alternatives (polyurethane and finite element analysis) that can serve in reducing the number of necessary biological samples. Future work will be to adapt results to human anatomy. Of clinical interest will be to influence bone pathologies such as post-surgical non-union, or bone functionality as part of haematopoiesis and endocrine secretion.

Numerical Nonlinear Static Analysis of Cutout-Borne Multilayered Structures and Experimental Validation

The influence of two different types of nonlinear strain-displacement kinematics (Green–Lagrange and von Kármán) and their importance are investigated in this analysis by computing the static deflection and stress (normal and shear) values of cutout abided composite structures. The structural deformation behavior under the external loading conditions is derived with a higher-order polynomial without hampering the strain and stress (in-plane and out-of-plane) continuity. The mathematical formulation of the curved structure is derived, and the governing equation order is reduced using nonlinear finite element steps. A generic computer code is prepared using the derived mathematical formulation in conjunction with the isoparametric finite element technique in a MATLAB environment. The final output (that is, the nonlinear deflection and stress data) is predicted using a robust nonlinear solution method (Picard’s iteration). The suitability of full-scale geometrical nonlinearity (Green–Lagrange strain) in the framework of a higher-order displacement field model for the laminated structure is established by comparing the experimental deflection data and published analytical solutions. Furthermore, a series of numerical examples is solved to show the influences of different individual and/or the combined parametric influences on the structural deflections and the normal/shear stress (in-plane and out-of-plane) values, including the variable geometrical shapes.

Application to visualize simultaneous vibrations of plates and ribs in a violin.

A code was written to explore, in real-time, experimental operational deflection shapes up to 5 kHz of a violin soundbox. The animations can be rotated and zoomed using the mouse, while the developed graphical user interface (GUI) allows controlling the frequency, amplitude, and frame-per-second rate. Also, some parts of the model can be hidden to improve the visualization of specific details of interest. The measurements-performed by students as laboratory exercise-include the ribs and not only the plates as it is traditionally done, thus the vibrations of the soundbox can be analyzed as a whole. Since the GUI was developed under a cross-platform open-source software (scilab), it can be easily installed and used as an educational tool for traditional in-person learning or online learning.

Studies on Effect of Recycled Aggregate on Deflection Characteristics of RC Slab

Substantial utilization of natural aggregates leads to the depletion of the naturally available resources. Hence an alternative approach is to utilize the recycled concrete aggregate (RCA) from the construction and demolition waste in the production of concrete and also in the prevention of dumping this waste in cultivable landfill. On the other side, codal provisions available for the predication of deflection in reinforced concrete one-way slab using effective moment of inertia (leg) were not comparable with the experimental values. Hence in the present study, it is proposed to study the load and deflection characteristics of simply supported slabs by varying the percentage of RCA content as 0 %, 50 % and 100 % under two point loading. Further, the work is extended to compare the deflection values obtained from experimental studies to the computed deflection values based on the IS 456:2000, ACI 318:2008 and BS: 8110. From the results, it is inferred that the replacement of natural aggregate with RCA does not affect the deflection characteristic of RC slab. Moreover, the computed deflection based on IS: 800, ACI and BS codal provisions does not match with the experimental deflection.

Experimental and numerical investigation of the effect of steel fibres on the deflection behaviour of reinforced concrete beams without stirrups

This paper presents an experimental and numerical study of the effect of steel fibres on the deflection behaviour and the contribution to the stiffness of tensioned concrete made by steel fibres reinforced concrete (SFRC) beams without stirrups, tested under four-point bending. The main testing parameters were the compressive strength of the concrete, the volume fraction of the fibres and their aspect ratio. The experimental deflections measured at mid-span of the beams were compared with the theoretical values predicted by three major design codes for reinforced concrete (RC) structures: the American ACI 318, the European Eurocode 2, the New Zealand NZS 3101, and also that predicted by Alsayed’s model. In the present study, a new model is proposed, taking account of the volume fraction, the aspect ratio and the orientation of the steel fibres. The instantaneous deflections predicted by the proposed model were compared with test results for SFRC beams extracted from the literature. The experimental results show that the deflection behaviour and the stiffness contribution of tensioned concrete increase with the addition of steel fibres. The proposed model yields reliable results and is found to be satisfactory in predicting the deflection of SFRC beams. In addition, the numerical ultimate load and corresponding mid-span deflection of beams predicted by non-linear finite element analysis using ANSYS© mechanical APDL software and considering four values of the fibre orientation factor (0, 0.45, 0.637 and 1), were compared with the experimental values. The predicted finite element results for the orientation factor of 0.45 are in close agreement with the experimental values. The numerical results show that the fibre orientation has a significant effect on the flexural behaviour of the SFRC beams.

Elastic Behavior of Nb2O5/Al2O3 Core-Shell Nanowires in Terms of Short-Range-Order Structures.

Single-crystalline niobium pentoxide nanowires (NWs) of length 10-15 μm and diameter 100-200 nm are synthesized by thermal oxidation of niobium substrates in a mild vacuum (3-10 mbar). Amorphous Al2O3 shells of varying thicknesses (10, 30, 40, and 50 nm) are deposited on top of the wires using atomic layer deposition. Bending tests of the uncoated Nb2O5 NWs and the Nb2O5/Al2O3 core-shell NWs are carried out inside a scanning electron microscope using a micromanipulator with a force measurement tip. The experimental deflection curves are modeled with Euler-Bernoulli (E-B) beam theory, and the Young's modulus is manipulated to determine the best fit. The Nb2O5 NWs with no shell are determined to have a Young's modulus of 67 ± 10 GPa, which agrees with the published data on Nb2O5 thin films. For core-shell NWs, only small deflections of the wires with 10 and 30 nm thick shells can be fitted with the E-B model when utilizing constant Young's modulus values of 67 GPa for the Nb2O5 core and about 160 GPa for the Al2O3 shell. When allowing for a change in the Young's modulus of the Al2O3 shell, the Young's modulus is determined to be at 120 ± 10 GPa for 10 nm and 145 ± 12 GPa for 30 nm at the highest applied load. For thicknesses of 40 nm and 50 nm, we observed a reduced but constant 120 ± 11 and 111 ± 10 GPa, respectively. Such behavior may result from structural disordering of the amorphous Al2O3 through reducing fractions of the densely packed polyhedra, while the fractions of the loosely packed polyhedra increase as a result of the increasing strain or the fabrication process. The increased disorder is associated with increased average interatomic spacing. Thus, the atomic bonding force and also the Young's modulus decrease.

Flexural behavior of PVA‐FRC GFRP reinforced concrete beams

AbstractFiber reinforced concrete beams are a popular research topic because of the improvement in the performance of concrete beams with fibers. PVA‐FRC GFRP reinforced concrete beams have better mechanical properties than those of ordinary reinforced concrete beams when considering the combination of multidirectional material properties. This article presents the results of an experimental study on the flexural behavior of PVA‐FRC GFRP reinforced concrete beams. Seven GFRP concrete beams were tested. The test variables included the PVA fiber content and GFRP diameter. The test results indicated that the existence of GFRP bars is effective for enhancing the load‐carrying capacity of RC beams and that PVA fibers can substantially inhibit the development of cracks in PVA‐FRC GFRP reinforced concrete beams and increase the midspan deflection. The experimental midspan deflection and maximum crack widths are also compared with theoretical predictions using new guidelines from the American Concrete Institute. Finally, the maximum crack correction formula for PVA‐FRC GFRP reinforced concrete beams is proposed.

Perovskite Nickelate Actuators

Micro-robotics is a burgeoning field, with potential applications in search and rescue, smart dust, advanced additive manufacturing and micro-surgery. A critical component enabling micro-robotic systems is efficient actuator materials. In this work we introduce thin films of NdNiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , a prototypical perovskite nickelate, as a potential material for MEMS actuation, providing up to 6.0% tensile volumetric strain via hydrogen-ion intercalation, resulting in an experimentally demonstrated output work density of 6.7 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and stress output in excess of 1.1 GPa via a unique hydrogen doping mechanism. Separately, a stiffened cantilever array is fabricated to measure experimental tip deflection, which matches expected deflections from a developed finite element analysis model. [2020-0330]

Impact of support material deformation in MEMS bulk micromachined diaphragm pressure sensors

In this work, experimental data and finite element analysis reveals deflection in diaphragm supporting material leading to non-linear pressure-reflection response. These results are contrary to the standard assumptions presented in literature, where modelling of deflection response in diaphragm pressure sensors is primarily carried out assuming a rigid supporting structure. An extrinsic fiber-optic Fabry–Perot pressure sensor, based on micro-electromechanical system, is developed and used to investigate optical deflection response. While the sensor is not novel, a series of experiments to validate support deflection phenomena are designed and carried out using a silicon membrane at gauge pressures from 0 to 1000 PSI in ambient temperature. The device is packaged with an industry standard stainless-steel housing typically used in plastic injection moulding. Sensor performance is compared to analytical and finite element modelling. Results suggest that the device is experiencing greater deflection than analytically predicted at pressures above 200 PSI, where a rigid support is assumed in existing literature. Based on these results, a modified analytical model is proposed to correct for this behaviour. The modified model is created through addition of a nonlinear component to an existing model, which is then fitted to the experimental data using least-square methods. Prediction of the experimental deflection results is improved from 81% error using a fixed-support analytical model to 4% error using the presented adjusted model. It is demonstrated that nonlinear effects are present and optically measurable in cases where deflection is lower than 1% of the membrane thickness. This work will aid in the implementation of high-resolution pressure sensors operating in harsh environment conditions.

Deflections of reinforced concrete beams with transverse openings of different geometries

The present study pertains to the in-plane bending deflections of reinforced concrete beams with multiple regular transverse openings along the beam length. The total deflections in the beam were obtained from bending deflections and the additional deflections from the Vierendeel panel action. The accuracy of the deflection estimates from the proposed formula were observed to depend on the opening geometry. Among different geometries, the presence of rectangular and parallelogram web openings resulted in the experimental deflections to deviate more considerably from the analytical values due to the stress concentrations around the corners of the openings. Consequently, a multiplier was incorporated into the deflection formula to account for the opening geometry. The new revised formula was found to generate analytical load-deflection curves in close agreement with the experimental ones and service-load deflections close to the FEA values of beams with varying amount of tension reinforcement. The diagonal reinforcement around the openings and the short stirrups in the posts and chords increased the accuracy of the analytical deflection estimates by reducing the undesired additional deformations in the beam due to the poorer integrity of the posts and chords around the openings.

Progression and characterization of polydimethylsiloxane-carbon black nanocomposites for photothermal actuator applications

The new development of polymer-based actuators triggers the progress of nanocomposites. Polymer materials are currently used in sensors, microfluidic devices, electrical and thermal actuators, and energy harvesting applications due to ease of availability, excellent tolerable properties, and customizable properties. The polymer-based nanocomposite can be driven by various stimuli, which is the actuator's emerging field. Thus, photothermal actuation is a thurst area of research transforming light energy into mechanical energy through the polymer material. The photo-responsive material can be prepared and tested for photo-actuation by incorporating the nanoparticles into the polymer. The present work focuses on developing polydimethylsiloxane (PDMS) and carbon black (CB) nanocomposite. The objective here is to investigate the photothermal actuator's performance by illuminating the infrared (IR) light source and studying its most influential characteristics, such as absorbance, thermal conductivity, and the thermal expansion coefficient.The PDMS / CB nanocomposite absorbs the IR light and then increases temperature, which is finally transformed into a beam deflection. Responses are measured as a result of time deflection using the Laser displacement sensor. It is noted that the deflection of the nanocomposite beam is linearly increased during illumination with light while it is exponentially decreasing when the light is turned off. The proposed polymer nanocomposite is approximately deflected by 9 mm in the duration of 16 s duration. Furthermore, the experimental deflection of the photothermal actuator is very close to theoretical results. The nanocomposite PDMS / CB reveals that there is an increase in absorbance by increasing the filler content. The nanocomposite conductivity is 35.2 % higher than the base material. As well, the thermal expansion coefficient decreases with an increase in carbon black content. The photothermal actuator's development is an ongoing process in which the material parameter, actuator geometry, and many more are modified. As a result, the photothermal bending performed can provide a means for various light-driven applications.

Combination of experiments and CFD analysis for in-flight wings deflections estimation

PurposeThis study aims to develop a new correlation method for prediction of in-flight wings deflections by integration of the experimental ground tests with computational fluid dynamics (CFD) analysis.Design/methodology/approachThe ground test results are implemented in the curve fitting process to determine deflections at 66 specific points (SPs) on the front and rear wing torque box. By using the obtained deflections and the corresponding applied loads, an experimental deflection equation (EDE) for each point is established through the Castigliano’s theorem. The CFD aerodynamic loads of typical aircraft, which have been obtained earlier by the authors, are once again used in the current research. The total applied loads to each part are achieved via summation of inertia and aerodynamic loads. The obtained loads are transformed to the equivalent concentrated loads at the SPs. By substituting the concentrated load values in the EDEs, the SPs deflections are achieved for mentioned flight conditions. The resulted deflections and the corresponding input flight parameters, i.e. M and α, are incorporated into a linear regression method for development of the appropriate in-flight deflection equations (IFDEs). The validity of IFDEs is approved by comparing IFDEs’ deflections with the corresponding ones calculated through EDEs for different flight conditions.FindingsAs an alternative approach to the fairly expensive flight tests, the IFDEs can be used to predict the in-flight wing deflections with comparable degree of accuracy.Originality/valuePrediction of actual wing deflections distributions without flight tests execution at any given flight condition.

Deformability of Steel-Fiber Beams with External Tape Reinforcement

In 2013, the Lviv National Agrarian University patented the construction of a steel-fiber concrete beam, additionally reinforced with an external steel ribbon armature with end anchors. This technical solution allows reducing the cost of the structure by reducing the complexity of its manufacture, due to the absence of a reinforcing frame in the structure. The purpose of this work is to develop proposals for a refined calculation method of deflections of steel-fiber concrete beams with tape reinforcement on the basis of our experimental studies. 3 beams with dimensions 1500x150x60 mm were manufactured. Beam B-1, reinforced with steel tape 1500x60x3 mm with end stops, did not contain fiber. Beams BF-2 and BF-3 in addition to the specified reinforcement contained fiber, corresponding the coefficient of fiber reinforcement by volume, ρfν = 1,5% i 2% respectively. Compressed prisms of 400x100x100 mm and stretched samples of 700x100x60 mm were also tested to determine the mechanical characteristics of concrete and steel-fiber concrete. Loose beams with a working run of 1400 mm were tested with concentrated force applied along the middle of the length. Mass production fiber produced both in Ukraine and abroad with bent ends HE 1050 1 mm in diameter and 50 mm in length was used for reinforcement. The percentage of fiber reinforcement by volume of concrete beams was taken ρfν = 1.5% and 2% to provide enough bearing capacity of the inclined sections. The cement of grade 400 (activity 42.3 MPa) of the Ivano-Frankivsk plant was used to obtain C20 /25 concrete. The test samples were made of fine-grained concrete containing sand from the Yasinets quarry with a fineness modulus of not more than 2.5. Mixtures for beams were made in a forced mixer. The composition of the mixture was chosen so that the settling of the cone did not exceed 4-6 cm and that the fiber did not settle to the bottom of the form. The composition of the mixture per 1 m3 of the mixture was as follows: cement - 549 kg, sand - 1647 kg, water - 285,5 l. The deflections of the steel-concrete beams were smaller than the steel-concrete beams at equal moments. For example, at the moment of 210 kN·cm the experimental deflection values of beams B-1, BF-2 and BF-3 were equal to 0.116; 0.081 and 0.064 cm, and at the moment 420 kN·cm - 0.380; 0.213 and 0.140 cm, respectively. In this paper, it is proposed to determine deflections using the Mora integral and taking into account the results of the calculation of beams by deformation method. The ratio of theoretical and experimental values of deflections was equal to 0.93 … 1.14.

Damage effect of steel circular tube subjected to fire and blast

Q345B steel circular tubes are widely applied in structural engineering applications, such as offshore platforms, bridges, and other structures, and they face potential risks of being subjected to the external loads of fires, explosions, or both during their service lives. In this study, the damage of Q345B steel circular tubes due to the combined action of fire and blast loading were analyzed. A specialized experimental platform was built, and experiments were performed on Q345B steel tubes with a range of wall thicknesses (a), fire loading durations (t), and stand-off distances (R) which means the distance between the bottom of the explosive and the upper surface of tube. The experimental local deflection, compressed degree, and local deformation volume are presented and studied in a quantitative manner. As the fire duration increased, the specimens underwent more noticeable deformation and damage. The local deflection amounts of the specimens treated with fire increased by 20%–50% compared to that of the specimen not exposed to fire at R = 17 cm. When R = 12 cm, the local deflection increased by 20%–120%. In addition, based on the stress–strain curves, the effects of the blue brittleness of the Q345B steel materials on the anti-blast performances of the specimens were examined. Finally, scanning electron microscopy was employed to explore the rupturing mechanism under a microscope.

Stiffness and Strength Analysis of Flexural RC beams strengthened with CFRP Sheets Considering the Influence of Pre-cracking

This paper presents experimental, numerical and analytical analysis of newly cast and pre-cracking flexural reinforced concrete beams strengthened with CFRP. In total, 9 intermediate-scale composite beams were cast and tested using 4-point bending test setup. Midspan deflection, width of the cracks, concrete and CFRP strains were measured during the experimental program. Clear efficiency of composite pre-cracked beams was observed in comparison to newly cast beams: enhanced flexural capacity and increased stiffness after appearance of primary cracks in tension zone. Good agreement was found comparing experimental and theoretical (EC2) deflections of RC beams strengthened with CFRP. However, for more detailed verification, the analysis should be extended with more specimens. The shear stress at the end of CFRP sheets between the concrete and CFRP increased rapidly until reaching maximum slip value, when the reinforced concrete beam strengthened with CFRP reaches 60-90 % utilization of load bearing capacity. All experimental results were compared with numerical and analytical calculations. Experimental, numerical and analytical results were in sufficiently good agreement.

Full-field experimental analysis of a sandwich beam under bending and comparison with theories

Sandwich plates with two thin stiff face-sheets and a soft center core have been used in many constructions for which the dominating load is transverse bending. Many theoretical/numerical analyses have been devoted to studying the deformation mechanism of such a structure. But relatively limited experimental investigations are present in this field and they are often self-content with little connection to the existing theoretical pursuits. In this paper, a composite sandwich structure made with carbon fiber woven face sheets and a relatively compliant foam core was loaded in 3-point bending. Images were captured of the specimen before and after deformation, which were then analyzed with a Digital Image Correlation (DIC) program. The full field displacements and strain fields were obtained for the specimen. The experimental deflection of the beam was compared with five theoretical models and one numerical solution. The result shows that only one model predicts the reality well.

Implementation of the fire beam element method into OpenSees for the analysis of structures in fire

The fire beam element method is a tool for structural fire analyses that simplifies a structure into a skeletal frame consisting of only beam and column elements. It considers a shifting neutral axis of each beam element, which is updated throughout an analysis. This method was implemented in the OpenSees software environment by adding two subclasses: one for the fire beam element added to the element class, and one for the member section, in which the neutral axis is iteratively adjusted for non-uniform temperature profiles. To validate the implemented model, three benchmark case studies were sourced from literature: (1) a heated cantilever beam with an analytical solution, (2) a steel beam in a furnace with high axial and bending forces and (3) a two-dimensional steel frame in a fire with complex behaviour such as non-linear heating, restraint and buckling. For (1) the fire beam element predicts deformations identical to an analytical solution. For (2) the fire beam element method simulates deformations with good accuracy across the entire time domain relative to experimental data, and simulations in the literature using Vulcan, although with experimental deflections typically being underestimated. For (3) fire beam element predictions are compared to experimental data and models developed in CEFICOSS, ABAQUS, SAFIR and LS-DYNA. Trends are typically accurately captured, with percentage differences varying. Runaway failure is predicted with 2 min of experimental data. A sensitivity analysis of the fire beam element model on mesh size of elements and fibres showed the runtime to be more sensitive to the number of elements than the number of fibres per element.

Behavior of Steel-Coconut Shell Concrete-Steel Composite Beam without and with Shear Studs under Flexural Load.

In this study, we investigated using coconut shell concrete (CSC) in double-skin steel plate sandwich beams, i.e., steel–concrete–steel (SCS) under flexure. Two cases—without and with shear studs to interconnect the bottom tension and top compression plates—were considered. Conventional concrete (CC) was used for comparison purposes. The effect of quarry dust (QD) in place of river sand (RS) was considered. Therefore, four mixes named as CC, conventional concrete produced using QD (CCQ), CSC and coconut shell concrete produced using QD (CSCQ) were used. Three different steel plate thicknesses were considered (4 mm, 6 mm and 8 mm). In total, twelve SCS specimens were tested to evaluate the flexural performance under two-point static loads. Study parameters include: partial and fully composite, ultimate moment and failures, deflection characteristics, ductility property, cracking behavior and strains in both tension and compression plates. It was found that the moment carrying capacity of the SCS sandwich beams increased when the thickness of the steel plate increased. Our results provided evidence that using QD in place of RS augmented the strength of beams. Theoretical deflections were underestimated the experimental deflection, except in one case. The SCS beams showed good ductility behavior. The SCS beams exhibited crack widths at yielding well below guideline values.