Eurocode Standards Research Articles

Structural Assessment Material and Fire Induced Strength Degradation Material of Multistory Building

This paper presents a detailed case study of a multistory building near Bombay Motors in Jodhpur that suffered severe fire damage, with temperatures reaching up to 900°C. The fire brigade arrived 30 minutes after the incident. Under the guidance of MBM University, research scholars conducted site investigations to analyze the impact of the fire on the building's materials, particularly concrete and reinforcement. The study reveals how the fire weakened these materials, leading to a significant reduction in the building's strength, especially in the columns. Notably, Floor 4 retained more strength than Floor 3, with strength differences ranging from +26.67% in one column to -20% in another. This highlights the variation in damage, indicating that while some columns on Floor 4 remained stronger, others experienced considerable strength loss. The findings emphasize the vulnerabilities exposed by fire and suggest ways to enhance building resilience. The research advocates for updates to building codes to incorporate better fire safety measures and provides valuable insights for improving firefighting and evacuation plans during emergencies. While the study is focused on this particular building, its results can also inform urban planning and fire risk management in other high-risk areas. By identifying weaknesses in design and materials, the study offers guidance for architects, engineers, and policymakers. Overall, the case study contributes to the goal of creating safer, stronger buildings in similar environments, promoting better construction practices and fostering safer cities. Additionally, the evaluation of residual strength was conducted using ISO 834 and Euro Code standards, and simulations performed through Abaqus software yielded results closely aligned with experimental techniques.

Structural Investigation of Drini River Bridges, Case Study of Structures Analyses

The Drini is the longest river not only in Albania, but in the west Balkan region, with a total length of 285 km. It is well known for a lot of number and famous bridges constructed since the antiquity period and continuing nowadays. This paper is focused on the structural development of bridges that used to be called “Kukësi Bridges” located over the White and Black Drini rivers. The old bridges were built and designed in 1974 using KTP Albanian national codes, carrying the first-class road until the building of a national road. The new bridge is in the final construction stage with the reconstruction of the national road highway, designed with advanced requirements regarding Eurocode standards. This paper analyses the structural bridges' progress related to historical and technical points of view.

3DLightSlab. Design to 3D concrete printing workflow for stress-driven ribbed slabs

In addressing the critical need to lower CO2 emissions in concrete construction, where slabs represent 43% of embodied carbon in midrise buildings, this study presents an innovative approach utilising 3D Concrete Printing (3DCP). We introduce 3DLightSlab, a carbon-efficient design for load-bearing slabs that leverages stress-driven design to generate isostatic ribs that adapt to diverse shapes, support arrangements, and load conditions, optimising structural layout and material efficiency. A case study demonstrates the design and fabrication of a slab supported by two columns tailored to withstand combined loads. Our methodology integrates Finite Element Analysis (FEA) for precise rib dimensionsing and density adjustment. The study includes the 3DCP of steel-reinforced prototypes, which were tested in 3-point bending and validated against Eurocode standards for serviceability, confirming the structural integrity of the slab under anticipated loads. This investigation demonstrates the potential of 3DCP in producing structurally sound, carbon-efficient horizontal structures, marking a significant step towards sustainable construction practices.

OPTIMAL SINGLE-STORY STEEL BUILDINGS UNDER HIGH LOADS

This paper presents the parametric optimization of single-story steel buildings subjected to high loads. In the parametric study, high loads of snow and wind are determined for different altitudes up to 3000 meters above sea level. The Alpine region and the Eurocode 1 standard are considered. The discrete mixed-integer non-linear programming optimization is performed for different altitude alternatives. The optimization model for the steel structure is developed and used. The mass objective function of the structure is subjected to dimensioning and deflection constraints defined by the Eurocode standards. The modified outer-approximation and equality-relaxation algorithm is applied. The optimal results obtained include the minimal possible mass of the structure, the optimal topology, the steel sections and the steel grade. In the case of a medium-sized single-story steel building, it was found that the structural mass increases by 2.7 times and the number of main portal frames increases by 80 % when the altitude of the building site is increased from 500 to 3000 meters above sea level. The optimal results clearly show how the structural mass and cross-sections increase with increasing load.

Structural assessment of an ASR-affected reinforced concrete bridge

ASR (alkali-silica reaction) has long been acknowledged as a key consideration when designing concrete structures in South Africa. This study raises awareness of the influence of ASR on the structural behaviour of reinforced concrete bridge structures. Aggregate type plays a role in how the ASR develops over the structural life cycle. Greywacke aggregate is found to be prominent in ASR-affected structures within the Western Cape region, and in the structure that was investigated. ASR decreases concrete tensile strength, compressive strength, and E-modulus over time. To develop a standardised approach that can be replicated on other bridge structures, a simply supported rectangular reinforced concrete bridge deck slab was analysed. The slab was modelled according to the construction drawings, including the reinforcement detailing, to determine the ultimate shear and moment resistance according to the code (BS 1972) used for the original design, and current Eurocode standards, for both unaffected and ASR-affected concrete. Traffic load was determined from the relevant TMH7 standard, and from weigh-in-motion data collected at a station on the high-traffic-volume route crossing the bridge. Due to compressive strength being the least affected material property by ASR deterioration, the ultimate resistance to original design loads was found to be sufficient.

Effects of carbonation and chloride ingress on the durability of concrete structures

The durability of concrete structures, which are designed for long-term use is predominantly determined by the resistance to chemical influences, i.e., the concrete?s ability to protect the reinforcement steel. The carbonation and the chloride ingress into concrete are the most significant causes of steel corrosion and the potential failure of the structure. The primary goal is to ensure that any significant damage does not occur during the structure's service life, primarily achieved by selecting an adequate thickness of the concrete cover. The issue is approached through calculations based on performance analyses, and the use of appropriate models for these chemical phenomena. The paper provides a brief overview and the methodology for analysing the impact on the durability of concrete structures in accordance with the leading international normative documents. The emphasis is on the recent changes introduced in second generation of European Eurocode standards. The consequences of the analysed phenomena are presented through the results of field tests conducted at salt factories, coke industries, and thermal power plants, and through laboratory tests. The tests were performed in order to develop a rapid prediction method for the measure of chloride ingress into concrete without the stimulating chloride ion migration by electricity, as an alternative to standardized tests.

Practical Implications of Structural Design of a Two-Span Rc Beam -Column Structure with Unequal Spans

The structural design of reinforced concrete (RC) beam-column systems with unequal spans poses unique challenges, especially when one span is significantly longer than the other. This paper explores the practical implications of designing a two-span RC beam-column structure where one span is at least three times longer than the other. The study highlights the key considerations in terms of load distribution, deflection control, reinforcement detailing, and the potential for differential settlement and vibrations. This research draws on Eurocode standards for design, provides an analysis of various load cases, and discusses practical solutions for ensuring structural integrity and serviceability.

New developments on fatigue in Eurocode on steel structures

The design rules for the verification of civil engineering steel structures against fatigue are compiled in the European harmonized design standard Eurocode EN 1993-1-9 released in 2005. This design standard is currently under revision, together with all other Eurocode design standards. Besides the inclusion of new developments and clarification, this revision aims for an improvement of user-friendliness and an extended degree of harmonization by reducing the number of Nationally Determined Parameters. The structure of the revised standard has also been modified to facilitate the application of the standard. In addition, the following major changes have been implemented: (i) Improvement of S-N curves in terms of the nominal stress method: clarification of stress computation, and re-organization of detail category tables. (ii) Improvement and extension of design rules for the hot-spot-stress and inclusion of design rules for the effective notch stress methods, in separate annexes. (iii) New annexes to determine the most common magnification and stress concentration factors for the modified nominal stress method as well as the stress ranges in preloaded bolts. Meanwhile, the final document of the project of the European design standard Eurocode prEN 1993-1-9 has been submitted to the “CEN Enquiry”. Thereafter it will go through the “Formal Vote”, planned for October 2024, before replacing the 2005 version throughout Europe.

Assessment of Existing Masonry Resistance Using Partial Factors Approaches and Field Measurements

The vast majority of existing structures in Croatia, as well as in other European countries, are made of unreinforced masonry. The seemingly ideal building material presents a great challenge for engineers in earthquake-prone zones. Given that structural failure can have significant consequences in terms of loss of human lives as well as financial losses, a comprehensive structural reliability assessment is needed. Old existing masonry structures often do not have design documentation, and even when they do, the initial mechanical properties have almost certainly degraded over time. That is why in situ testing is of great importance, but masonry is also characterized by a large scattering of results. After recent severe earthquakes in Croatia, more than ever, there is a need for a more reliable assessment of existing masonry structures. This paper presents reliability approaches for resistance evaluation of existing masonry in a real case study where basic failure modes of the masonry were observed. First, the data recommended in standards were used, followed by the updated data obtained from the flat-jack test. Finally, the design value method (DVM) and the adjusted partial factor method (APFM) were used. These methods align with Eurocode standards for new structures but are also adaptable for the assessment of existing structures. Differences in the results between the existing and the new version of the standard were observed, as well as an increase in the obtained resistances with an increase in the complexity of the methods used. Also, the influence of in situ testing proved to be an important factor in the analysis.

The Effect of Earthquake on Temporary Structures during Bridge Construction with Different Column Heights

This research aims to study the effect of earthquakes on temporary structures during bridge construction with different column heights for analysis and evaluation of the damage to temporary structures known as “Launching Gantry” and bridge structures. The primary focus is on temporary structures used in bridge construction with spans of 45 meters and heights of 7, 19, and 28 meters. The research examines four different stages of bridge construction: a single-span bridge, launching the gantry to install the next span, preparing to hang prestressed concrete box girders, and hanging the prestressed concrete box girders. The study uses 12 models created with the midas Civil computer program and nonlinear time history analysis to simulate seismic acceleration in the Bangkok area during the construction stage with a return period of 39 years to determine the internal force and the deformation. As a result, the forces were compared to the resistance according to Eurocode standards to evaluate the damage. The results show that the bridge structure is undamaged, with only minimal deformation, but significant damage was found in the legs of the supports, particularly the front support. The flexural moment and axial force were 1.53 times greater than the resistive strength, and the leg experienced deformation in the transverse direction of the bridge up to 71 millimeters, or 1/77 of the leg height.

Assessment of Properties of Structural Lightweight Concrete with Sintered Fly Ash Aggregate in Terms of Its Suitability for Use in Prestressed Members.

The main aim of the paper was to assess whether the lightweight concrete with a new type of sintered fly ash aggregate can be used as a structural material for post-tensioned elements subject to high effort. This purpose was achieved by comparison of the properties of lightweight aggregate concrete with Certyd aggregate (LWAC) and normal-weight concrete with dolomite aggregate (NWAC) of similar strength in terms of their suitability for use in prestressed members. Special emphasis was placed on long-term, relatively rarely performed tests of rheological properties such as shrinkage and creep. The research was conducted on standard specimens as well as on plain and post-tensioned beams of bigger scale, which could reflect better the behavior of the materials in a destined type of structural members. The carried out tests showed that, despite the expected lower density and modulus of elasticity, LWAC revealed comparable tensile strength and lower shrinkage and creep in the whole time of observations (ca 1.5 years) in comparison to NWAC. Moreover, the total loss of prestressing force for beams made of LWAC was slightly lower than for NWAC. Estimations of tensile strength and modulus of elasticity values according to the standard Eurocode EN-1992-1-1 for both concrete types turned out to be satisfactory. However, the rheological properties of the tested lightweight concrete seemed to be considerably overestimated.

A numerical insight into the reliability of seismic strength models for masonry piers and spandrels

With the aim to provide an insight on the effectiveness of existing formulae for the flexural and shear strength of masonry piers and spandrels, this paper reports and compares results obtained from pushover analyses performed on a set of plane masonry walls. As reference, the formulae provided by the Italian Building Code (IBC) were considered. Nonetheless, the formulations provided by IBC are similar to the ones reported in the Eurocode Standards (ES), and thus conclusions of this paper can be extended to the latter. Three types of masonry walls were considered which differ in the span-to-height ratio b/h of the masonry beams, namely: a) slender beams (b/h = 2.0); b) intermediate beams (b/h = 1.00) and c) short beams (b/h = 0.75). For each masonry wall, the unreinforced configuration (URS) was compared with two resisting schemes: concrete ring beams (RSB) and steel chains (RSC). Therefore, a total of 9 types of masonry walls were considered which differ in terms of geometry and resistance mechanisms. To perform the pushover analyses, the finite element technique was employed by using three different load distributions. The results expressed in terms of inner forces on the piers and spandrels were subsequently compared with the formulae for flexural and shear strength provided by IBC. The comparisons showed that the reliability of these equations is at least questionable, especially for the prediction of the spandrels’ strength. In this case, the strength models provided by the Standards underestimate by a large amount the real strength both for the unreinforced and the strengthened walls, especially in the case of slender spandrels in strengthened walls.

DESIGN OF TRANSITION JUNCTIONS OF SILOS’ CONICAL HOPPERS ACCORDING TO EUROPEAN STANDARD EUROCODE

Problem statement. Today, the food security of the world is one of the main issues for the political, economic and scientific community, and the recent crisis with the export of Ukrainian grain only intensifies the urgency of the problem. The important part of this issue is creation of reliable and safe grain storage silos. An analysis of recent accidents in silos, especially with conical hoppers, revealed a range of imperfections in outdated regulatory practices that Ukraine inherited from the Soviet building norm system. A limited list of agricultural crops, ignoring the statistical spread of their physical and mechanical characteristics, not differentiating between the stress-strain state for filling and discharge silos, the absolute absence of guidelines and recommendations for the design of principal connections - this is a far from complete list of shortcomings and omissions of outdated Soviet standards. With the entry into force of the new Ukrainian norm DBN V.2.6-221:2021 “Designs of steel silos with a corrugated wall for grain”, the situation should have changed. Firstly, the new standards take into account the world experience in design, construction and fabrication of silos, and secondly, they have a direct and legitimate reference to the necessary standards of the Eurocode system, in which a modern engineer can find answers to a wide range of practical questions. Unfortunately, the introduction of this, without exaggeration, modern and extremely important standard into construction practice is constantly ignored. On the one hand, this is due to the unwillingness of Ukrainian manufacturers to switch to new European and more rigid requirements for reliability and safety, on the other hand, the fear of Ukrainian engineers in front of the complex and extensive Eurocode standardization system. The purpose of the article (ignoring the financial commercialism of individual silo manufacturers) is explain to domestic designers a few provisions of the new DBN V.2.6-221:2021 related to the design of silos with a conical hopper. In particular, the design of one of the very important units at the point of transition of the cylindrical part of the silo to the conical hopper. Methodology. For this, the general ideology and methodology of the limit state method, implemented in the Eurocode standards through the system of partial reliability factors, as well as classical methods of structural mechanics, which are still not reflected in the system of building regulation of modern Ukraine, are used. Results. As a result, clear recommendations for the design of the transition junction of silos with a conical hopper in accordance with Eurocode and DBN V.2.6-221:2021, as well as clarification of “special” points that are not properly covered in both regulations. Conclusion. The recommendations and explanations given in the article, firstly, accelerate the introduction of the new DBN V.2.6-221:2021 into engineering practice, which is harmonized with the Eurocode system, and secondly, allow to achieve more reliable and safe design solutions in the field of silos fabrication, in thirdly, they deactivate the chronic design fear of Ukrainian engineer before the European school of building standards.

Ultimate bearing capacity of UHPC-encased CFST medium-long columns under axial compression

To study the effect of slenderness ratio on the ultimate bearing capacity of UHPC (ultra-high performance concrete)-encased concrete-filled steel tubular (UC-CFST) columns, a total of nine specimens under axial compression were tested. A finite element model, considering the effects of material nonlinearity and interaction between concrete and steel tube, was developed. A full-range analysis was carried out on the typical load–deformation response of the UC-CFST medium-long columns. The experimental and numerical analysis results showed that with the increase in slenderness ratio, the deformation capacity of the UC-CFST columns increased, the ultimate bearing capacity decreased, and the failure mode changed from exceedance of compressive strength to loss of stability. The internal forces and stress distributions at the mid-height section of the columns at different stages were also investigated. Finally, the applicability of various methods for calculating the ultimate bearing capacity of ordinary concrete-encased CFST (OC-CFST) columns to UC-CFST columns was discussed, including the methods recommended by Chinese standard T/CECS 188-2019, European standard Eurocode 4, Australian/New Zealand joint standard AS/NZS 5100.6 : 2017 and American standard ANSI/AISC 360-16. It was found that the method recommended in AS/NZS 5100.6 : 2017 was suitable for calculating the ultimate bearing capacity of UC-CFST medium-long columns.

Static and seismic design of Dry Stone Retaining Walls (DSRWs) following Eurocode standards

Dry Stone Retaining Walls are structures made of rubble stones assembled without mortar and have been present worldwide for centuries. Today, they still constitute an attractive alternative to building techniques involving higher embodied energy, such as reinforced concrete walls. This study uses a pseudo-static approach to give design recommendations to maintain this built heritage and allow its modern construction. Both non-seismic (Eurocode 7) and seismic (Eurocode 8) cases are addressed. The present work confirms that a seismic design is not critical and is therefore not required for zones with a design acceleration below 0.05g. In addition, this work highlights the significant positive effect of the stone bed inclination and the internal wall face batter. Finally, depending on the wall site conditions and the seismic zone associated with the project, general design recommendations are given to optimise the volume of stones used, which are illustrated in the case of France. These recommendations based on pseudo-static analyses are already usable in practice for low to moderate seismic areas as the required retaining wall dimensions can be easily implemented on-site. In addition, it is also shown that the actual French recommendations for these walls fully comply with Eurocode 7.

Comparison of Provisions for Nonslender Reinforced Concrete Columns: American Concrete Institution, Eurocode, Indian Standard, and Canadian Standards Association

Comparison of Provisions for Nonslender Reinforced Concrete Columns: American Concrete Institution, Eurocode, Indian Standard, and Canadian Standards Association

Influence of PVB Interlayer Mechanical Properties on Laminated Glass Elements Design in Dependence of Real Time-Temperature Changes.

Most used laminated glass is composed of float glass plies bonded together with a viscoelastic Polyvinyl Butyral (PVB) interlayer. The shear stiffness of the polymeric interlayer is the key factor in the behavior of laminated glass. Structural engineers in the past were designing laminated glass regardless of the shear coupling of the plies. This approach with a high level of reliability led to expensive laminated glass structures due to insufficient knowledge of foil properties. Most of the current standards suggest methods that consider the shear coupling of the plies. This paper presents the experimental data from a static loading test performed on a laminated glass panel exposed to changing temperatures. The deformations were observed for 48 h. The measured results were compared with the known analytical design approaches and in addition with the finite element modeling (FEM) analysis in the available software for laminated glass design. A simplified design approach that simulates foil behavior in dependence on load duration and temperature change was adopted in this study. Design approaches that use effective thickness calculations are used with the Young and shear relaxation modulus provided by the foil producer. The imprecision of the Eurocode standards for glass design, and the propensity to change the approach to the calculation by introducing more precise parameters were expounded. The results when combining the time-temperature superposition (TTS) and the Wölfel–Bennison approach were found to be in very good agreement with the FEM analysis of 3D solid elements in Abaqus and measured data.

Optimal Design and Competitive Spans of Timber Floor Joists Based on Multi-Parametric MINLP Optimization.

This study investigates the optimization of the design of timber floor joists, taking into account the self-manufacturing costs and the discrete sizes of the structure. This non-linear and discrete class of optimization problem was solved with the multi-parametric mixed-integer non-linear programming (MINLP). An MINLP optimization model was developed. In the model, an accurate objective function of the material and labor costs of the structure was subjected to design, strength, vibration and deflection (in)equality constraints, defined according to Eurocode regulations. The optimal design of timber floor joists was investigated for different floor systems, different materials (sawn wood and glulam), different load sharing systems, different vertical imposed loads, different spans, and different alternatives of discrete cross-sections. For the above parameters, 380 individual MINLP optimizations were performed. Based on the results obtained, a recommended optimal design for timber floor joists was developed. Engineers can select from the recommendations the optimal design system for a given imposed load and span of the structure. Economically suitable spans for timber floor joists structures were found. The current knowledge of competitive spans for timber floor joists is extended based on cost optimization and Eurocode standards.

Heat transfer model verification for thermal monitoring system of integral bridges

Thermal actions considered on abutments of integral bridges by the European standard (Eurocode 1) might be in variety of certain situations underestimated. Based on this assumption, thermal monitoring system has been designed and installed into structure of bridge No. 27-117. Temperature profiles in five certain spots are being measured to provide sufficient basis for evaluation of real thermal actions on abutments of integral bridges. For purpose of measurement verification, elementary heat transfer models for finite element method solver were created. These models are being loaded by simplified temperature profiles reached in real time in-situ. Evaluated models provide verification data to compare with measured temperature profiles in structure and might provide information about temperature profiles probably reached during extreme weather situations.

Emissivity of hot-dip galvanized surfaces in future development of EN 1993-1-2

PurposeThis study aims to propose a new design value, based on experimental and numerical studies, for surface emissivity of zinc hot-dip galvanized members exposed to fire.Design/methodology/approachThe paper sums up experiments, used specimens and also shows results. Four experiments were performed in a horizontal furnace and one test in a fire compartment of the experimental building. Several tests were carried out for determination of the surface emissivity of galvanized steel structures in fire. The experimental and numerical studies were used for preparation of new generation of the structural steel fire standard Eurocode EN 1993-1-2:2025.FindingsHot-dip galvanizing is one of the most widely used processes for corrosion protection of steel products. The new design value for surface emissivity of zinc hot-dip galvanized members exposed to fire is determined using experimental results as 0.35. The value is proposed for next generation of EN 1993-1-2:2025. If hot-dip galvanization additionally can contribute beneficially to the fire resistance of unprotected steel members, it would be a huge economic advantage.Originality/valueExperimental studies in the past years have indicated the influence of hot-dip galvanizing on the heating of steel members. This study suggests 50% reduction of the surface emissivity of a carbon steel member. This amendment will be incorporated in future versions of Eurocodes 3 and 4 and has already been implemented in some fire design tools for steel members in order to consider the beneficial contribution of hot-dip galvanized for fire-resistance requirements of less than 60 min.