EC3-Compatible Methods for Analysis and Design of Steel Framed Structures

The behaviour of steel structures is affected by two nonlinearities—the geometric and material nonlinearity—and by the unavoidable presence of imperfections. To evaluate the ultimate capacity of a structure, these effects should be taken into consideration during the design process, either explicitly in the analysis or implicitly through the verification checks. In this context, Eurocode 3 provides several design approaches of different complexity and accuracy. The advantages and disadvantages of these approaches are discussed. Five different methods in conformity with the Eurocode provisions are applied for the design of four moment resisting steel frames of varying slenderness. The influence of nonlinearities and imperfections in respect to the slenderness of the structure is illustrated. The examined methods are compared in terms of the predicted ultimate capacity and their efficiency is assessed against the most accurate between them, i.e., an advanced geometrically and materially nonlinear analysis. It is shown that considerable differences arise between the methods. Nevertheless, except for the commonly used 2nd order analysis followed by cross-section verifications, the remaining methods are mostly on the safe side.

Experimental and numerical evaluation of the axial capacity of cracked tubular members

This paper presents the experimental and numerical results for the axial capacity of cracked tubular steel members. Experimental tests of 11 columns in compression with simulated cracks of different sizes, defined as the percentage of the circumference (12%, 23.5% and 38.5%). The crack-tips were further treated by drilling a crack arresting hole. These specimens were then modelled by finite element analysis which were verified to match the experimental test. The DNVGL-RP-C208 standard was used as basis for performing the numerical finite element analysis. In addition, the capacity of the columns was calculated according to the 2004 revision of the NORSOK N-004 standard. The experimental tests indicated that the capacity in compression did not change significantly with the presence of cracks and crack arresting holes. The results from the numerical finite element analysis show a good agreement with the experimental work. However, the compressive capacity according to NORSOK N-004 shows a significant deviation to the safe side.

Machine Learning for Modeling the Bearing Capacity of Prestressed Concrete Elements Damaged by Corrosion

This work aims to study the prediction of bearing capacity of prestressed concrete beams subjected to accelerated corrosion process using Machine Learning (ML) techniques. After data collection, the results were used to model the behavior of flexural stress, and predict their final load capacity, considering position, length, and width of the cracks generated by corrosion as well as loss of bearing capacity. The study presents an analysis of 363 days old beams damaged by corrosion, connected to a galvanostat for 62, and 121 days to make faster the process. Six beams were analyzed; five of them were used to train the model, the other works as a basis to compare the results thrown by the model with the real data. After the treat, the results showed that Bagged Trees Model fits better to real data, it was seen that removing atypical data improves the correlation of predicted and real data. The actual data were compared with two different prediction analyzes; for the first one, the atypical data were not removed; in the second one, the atypical data were eliminated with a statistical analysis. Obtaining relative error percentages of 15.18%, 14.59%, presenting two predictions: final load of 1444 kg and 1126 kg. Which means a resistant moment of 650 T-m, and 506.7 T-m respectively, taking as a prediction the second value in the safe side.

Exterior Wood-Frame Walls—Wind–Vapour Barrier Ratio in Denmark

Wood-frame walls in cold climates are traditional constructed with a vapour barrier that also constitutes the air-tightness layer. Polyethylene foil as a vapour barrier is likely used; however, other building materials can be used to obtain correspondingly sufficient properties. 1D hygrothermal simulations were conducted for a wood-frame structure to investigate the wind–vapour barrier ratio, and if the vapour barrier of polyethylene foil could be omitted and replaced by other materials. The results were postprocessed using the VTT mould model. The results showed how wood-frame walls can be designed with respect to internal humidity class and diffusion resistance divided into three categories: no risk for mould growth, needs further investigation, and is not performing well as the risk for mould growth is present. For internal humidity classes 1–3, the ratio between wind and vapour barrier must be about 1:5, and 1:10 for classes 4 and 5 to be on the safe side. Simulations were performed for the climate of Lund, Sweden, which were used to simulate climate in Denmark too. Nevertheless, the results are related to climate data and, thus, the location.

Mesenchymal Stromal Cells: Potential Option for COVID-19 Treatment

The COVID-19 pandemic has significantly impacted the way of life worldwide and continues to bring high mortality rates to at-risk groups. Patients who develop severe COVID-19 pneumonia, often complicated with ARDS, are left with limited treatment options with no targeted therapy currently available. One of the features of COVID-19 is an overaggressive immune reaction that leads to multiorgan failure. Mesenchymal stromal cell (MSC) treatment has been in development for various clinical indications for over a decade, with a safe side effect profile and promising results in preclinical and clinical trials. Therefore, the use of MSCs in COVID-19-induced respiratory failure and ARDS was a logical step in order to find a potential treatment option for the most severe patients. In this review, the main characteristics of MSCs, their proposed mechanism of action in COVID-19 treatment and the effect of this therapy in published case reports and clinical trials are discussed.

Behavior of the Experimental Flat Slab Specimen Supported by an Elongated Column

The paper deals with the results of a loading an isolated fragment of flat slab specimen with two openings located close to the column. Slab specimen was supported by an elongated column and was without shear reinforcement. The accuracy of the relevant design models for prediction punching resistance was tested with obtained test results. All design models provided punching capacity on the safe side. The best accuracy has been achieved by non-linear analysis that was carried out with Atena software.

Experimental and Numerical Study of the Elastic SCF of Tubular Joints

This paper provides data on stress concentration factors (SCFs) from experimental measurements on cruciform tubular joints of a chord and brace intersection under axial loading. High-fidelity finite element models were generated and validated against these measurements. Further, the statistical variation and the uncertainty in both experiments and finite element analysis (FEA) are studied, including the effect of finite element modelling of the weld profile, mesh size, element type and the method for deriving the SCF. A method is proposed for modelling such uncertainties in order to determine a reasonable SCF. Traditionally, SCF are determined by parametric formulae found in codes and standards and the paper also provides these for comparison. Results from the FEA generally show that the SCF increases with a finer mesh, 2nd order brick elements, linear extrapolation and a larger weld profile. Comparison between experimental SCFs indicates that a very fine mesh and the use of 2nd order elements is required to provide SCF on the safe side. It is further found that the parametric SCF equations in codes are reasonably on the safe side and a detailed finite element analysis could be beneficial if small gains in fatigue life need to be justified.

Evaluation of rockfalls at a historical settlement area in the Ihlara valley (Cappadocia, Turkey) using different methods

Rockfalls are one of the most dangerous natural events in hilly terrains. This study presents the results of an investigation program to analyze the possibility of a rockfall from a slope to nearby residential buildings in a historical settlement area. Various rockfall analysis techniques were implemented in the study for this purpose. The kinematical analysis revealed the potential of different structurally controlled modes of failure in the slope, especially wedge type and block toppling were the most significant ones. Finite element analysis suggested a stable slope considering the safety factor of 2.19 for the existing geological and geotechnical conditions of the studied slope case. A possible rockfall trajectory was determined and located as an input in the 2D rockfall program based on the field measurements. Different shapes and sizes of blocks were used in the rigid body model for a more realistic numerical simulation of rockfall events. According to the 2D model results, there was no danger of rockfall for the investigated downslope buildings. However, to stay on a safe side, a suitable control measure with a specified dimension was proposed to manage rockfalls in the study area.

From glucose lowering agents to disease/diabetes modifying drugs: a “SIMPLE” approach for the treatment of type 2 diabetes

During the last decade we experienced a surge in the number of glucose lowering agents that can be used to treat patients with type 2 diabetes. Especially important are the discoveries that sodium glucose co-transporter type 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1 RA) improve patients’ cardiovascular and renal outcomes. Accordingly, various medical associations have updated their guidelines for the treatment of diabetes in this new era. Though not agreeing on every issue, these position-statements generally share a detailed and often complex workflow that may be too complicated for the busy and overworked primary care setting, where the majority of patients with type 2 diabetes are managed in many countries. Other guidelines, generally those from the cardiology associations focus primarily on the population of patients with high risk for or pre-existing cardiovascular disease, which represent only the minority of patients with type 2 diabetes. We believe that we should re-define SGLT2i and GLP-1 RA as diabetes/disease modifying drugs (DMDs) given the recent evidence of their cardiovascular and renal benefits. Based on this definition we have designed a SIMPLE approach in order to assist primary care teams in selecting the most appropriate therapy for their patients. We believe that most subjects newly diagnosed with type 2 diabetes should initiate early combination therapy with metformin and a prognosis changing DMD. The decision whether to use GLP-1 RA or SGLT2i should be made based on specific patient’s risk factors and preferences. Importantly, DMDs are known to have a generally safe side-effect profile, with lower risk for hypoglycemia and weight gain, further promoting their wider usage. Early combination therapy with DMDs may improve the multiple pathophysiological abnormalities responsible for type 2 diabetes and its complications, thus resulting in the greatest long term benefits.