bluuebunny/crossref_metadata_2025 huggingface dataset:
SHEAR STRENGTH OF DETERIORATED STEEL GIRDERS IN MULTI-GIRDER BRIDGES
Authors: Bao Amanda , Guillaume Caleb , Moraes Alana
Published: February 2025

Bridge deterioration is mainly caused by repeated traffic loads and adverse environmental exposure. According to the 2017 American Society of Civil Engineers' infrastructure report card, more than 9% of the bridges in the United States were labeled structurally deficient. For steel bridges, the most dominant deterioration form is corrosion, which is characterized by the metal area loss resulting in structural capacity reduction. Corrosion is very common in steel multi-girder bridges because of moisture exposure, leakage through bridge joints as well as the frequent use of deicing detergents during the winter season in cold regions. Over the years, the rust can be serious enough to disconnect the web from the flanges of the girder, which poses significant concerns for load capacity especially at girder ends. This research studies shear strength loss in deteriorated steel multi-girder bridges by 3-D finite element models built in ABAQUS. Our analysis is focused on web area loss and web thinning due to corrosion, and their consequences for shear and web buckling capacity reduction. Area loss will be modeled by removing materials from the web, and web thinning will be simulated by reducing the web thickness. The numerical models resemble real steel corrosion forms by changing the shape, size and location of the area loss. A load rating method will be proposed based on the analyses.
BEHAVIOR OF RC BEAM RETROFITTED USING ULTRA HIGH-PERFORMANCE CONCRETE UNDER IMPACT LOADS
Authors: Al-Osta Mohammed Ali
Published: February 2025

Several new types of materials have recently been used as retrofitting materials for structural elements such as ultra-high performance concrete with steel fiber reinforcement (UHPFRC). These materials are used as jacking to enhance the strength and ductility reinforced concrete (RC) beams. Considerable attention has been focused on the response of retrofitted RC beam under static loads but the behavior of such beam under impact loading is somewhat lacking. Therefore, in this study, a 3-D finite element model (FEM) of retrofitted RC beams under impact loading using non-linear finite element software (ABAQUS) was investigated. Since experimental work on this topic is scarce, the FEM is validated using the results of retrofitted RC beam under static loads. The impact load was applied in ABAQUS as equivalent to an initial velocity of 2500 mm/s. A parametric study was carried out to study the flexural response of RC beams retrofitted with different thicknesses and strengthening configurations of UHPFRC under impact loading.
STRUCTURAL OPTIMIZATION USING AN ADAPTIVE RBF APPROACH
Authors: Jarosch Erica , Wang Qian , Schmotzer Lucas , Kim Yongwook
Published: February 2025

This paper presents an adaptive radial basis functions (RBFs) metamodeling method for design optimization of structures. Various numerical techniques have been developed and adopted in structural and multidisciplinary optimization. To evaluate responses of a structural or mechanical engineering system, finite element (FE) analyses are routinely used. An FE code shall be integrated with an optimization algorithm in a nested analysis and design of structures. Therefore, software input/output programming is required. A metamodeling method, on the contrary, expresses structural responses using an approximate function, so that the FE software is not directly coupled in the numerical optimization loop. Any optimization algorithm can be applied to find the optimal design, based on the explicit response functions. In this study, numerical examples were created and FE analyses were first performed at sample points. Subsequently, metamodels were constructed and a gradient-based optimization algorithm was applied. At the optimal point of one adaptive iteration, accuracy of the RBF metamodel was checked, and additional sample points were added to the sample pool to improve the model accuracy. The adaptive iterations continued, until the convergence of the objective function was achieved. The proposed optimization method worked well for a numerical example, and the optimal result was found within a few adaptive iterations.
ICONIC STRUCTURES: CASE STUDY OF A HISTORIC MUSEUM WITH NOTABLE SPANS DESIGNED IN CONCRETE
Authors: Ede Anthony , Williams Adeoti , Oni Olatunji , Olofinnade Oluwarotimi , Oyebisi Solomon , Alayande Tolulope , Mark Oluwaseun , Ofuyatan Olatokunbo , Oluwafemi John
Published: February 2025

The emergence of iconic structures around the world increased tourism and economic status of the of host cities. Iconic structures stand out and attract the attention of the general public due to their daring structural limits and aesthetic forms. Hence, the design idea of an iconic historic museum is conceptualized in this research. This paper models an art center, analyses and designs the critical elements according to BS 8110, trying to determine the feasibility of a large-cantilevering structure with numerous curves being achieved. The activities carried out in this research involved a systematic modeling of the structure with Building Information Modeling (BIM) tools, analysis and design in reinforced concrete with particular emphasis on the cantilevered wing of about 37.5m. Numerous load combinations were applied, and various member section properties were experimented. The results obtained from the analysis of the designed reinforced concrete model identified the structural efficiency of certain critical members in the west wing of the building and how they were made to adhere to structural limits in the code of practice by ensuring deflections of critical cantilevered members did not exceed the limit. A unique arrangement of structural systems has been combined to solve the problem of deflection of the seemingly impossible cantilever of 37.5m.
VIBRATION RESPONSE OF A FOOTBRIDGE DUE TO PEDESTRIANS' MOVEMENTS
Authors: Setareh Mehdi , Kadam Ruthvik , Bukhari Mohammad
Published: February 2025

Failure of footbridges in England and France due to excessive vibrations from marching soldiers in the nineteenth century resulted in many fatalities and injuries. The unexpected lateral vibrations of the Millennium Bridge over the Thames River in London was a watershed event as large number of research studies were conducted on this subject following this incidence. However, there are still a number of issues related to vibration serviceability of footbridges that require further studies. Among these are: the amplification of structural response when a group of pedestrians cross a footbridge as compared to a single individual (group effects). This is important as footbridge vibrations are usually computed when subjected to one pedestrian’s crossing and are magnified to estimate those generated by a group of people. Therefore, it is important to conduct vibration testing of footbridges to better define the group effects. This paper presents an experimental study of a footbridge susceptible to vibrations due to human movements. With the help of a group of volunteers, the group effects were computed as a function of the group size. It was found that the results were not completely consistent with those in the literature. Conclusions are made based on the results of the data analysis.
EFFECTS OF HUMAN-STRUCTURE INTERACTIONS ON THE DYNAMIC PROPERTIES OF BUILDING FLOORS SUSCEPTIBLE TO VIBRATIONS
Authors: Setareh Mehdi , Renard Stephanie
Published: February 2025

Excessive vibrations of building floors due to human movements have become an important vibration serviceability problem for building designers and owners. A series of vibration tests on a full-scale laboratory floor with different numbers of humans in various postures were conducted. Using this data, the dynamic properties of a two-degree-of-freedom (2-DOF) dynamic system representing groups of people in different postures were computed. A 3-DOF model representing the floor and humans was developed and its dynamic properties were defined in terms of non-dimensional parameters. The dynamic properties of the floor were measured when occupied by groups of people in different postures and compared to those predicted using the 3-DOF dynamic model considering the identified human models. The results showed that the predicted properties were within the range of those found from the measurements, which validated the identified human dynamic models. This study also showed how the presence of humans can affect the natural frequency and damping ratio of a floor system.
THE FOUNDATIONS OF CONTINUUM DAMAGE MECHANICS
Authors: Yazdani Siamak , Borgersen Sevenn , Gurgun Asli Pelin , Nazari Hossein
Published: February 2025

Damage Mechanics has become a useful theory in describing the nonlinear behavior of solids driven by the nucleation and growth of cracks and microcracks. This approach, based on the first principles of mechanics and thermodynamics, has also been combined with classical theories of plasticity to address a wide range of loading applications. In spite of the many different damage mechanics models and representations that are proposed, the foundation of damage mechanics is not well understood or at least not thoroughly published giving rise to the many inaccurate definitions and formulations. The intent of this paper is to provide the background of the continuum damage mechanics outlining the fundamentals on which this field theory is set up. The internal variable theory of continuum thermodynamics is reviewed and is shown that with Legendre transformation technique, various potential functions can be developed for damage mechanics formulation in either stress or strain space. The concept of constrained or neighboring equilibrium state is also introduced and is explained. The paper will conclude with the derivation of the general damage potential and a suggestion is given for the isotropic damage formulation with the resulting uniaxial stress-strain relation.
LOAD BEARING STRUCTURAL ASSEMBLY
Authors: Russell Bradford
Published: February 2025

This article is based on an invention focused on absorbing and redirecting forces two dimensionally or three dimensionally in any mechanism that relies on force resolving members, so more benefits of the mechanism can be achieved. This Assembly is focused on new ideas for framing and connections to resolve forces so the rigidity between members can be minimized and the Assembly can sustain performance under longer durations and more unique loadings, i.e., seismic loading on structure. The Assembly uses several techniques and fundamentals for efficient force dissipation with, or without deflection while creating a controlled rotation when loaded. The allowable arrangement of the Assembly within itself (web members within outer and inner rings and arcs), and as an assortment of assemblies, can be limitless. This arrangement, configuration of web members, numbering, width and flexibility, can be arranged for a predictable and controlled deflection or rotation in any direction, due to loading from any direction and type, thus creating a load bearing and load dissipating Assembly with greater efficiency, and advance the life of interacting parts under loadings, i.e., seismic loading of structures. This Assembly, in particular the web members, can be an arrangement and properties of arcs to offer a desired response, as well as create a rotation when loaded.
A COMPARISON BETWEEN PROBABILISTIC AND POSSIBILISTIC NUMERICAL SCHEMES FOR STRUCTURAL UNCERTAINTY ANALYSIS
Authors: Sekkak Hamza , Modares Mehdi
Published: February 2025

Analysis of a structure is a crucial procedure to ensure its reliable design and performance. Because of complexities present in the closed-form structural analysis methods, numerical schemes have become the standard of practice. These schemes are generally performed deterministically. However, the input parameters defining the material and geometric properties may possess uncertainties. They can arise from various sources including modeling, manufacturing, and construction errors. The quantification of uncertainties is generally based on either probability theories (using random variables) or possibility theories (using interval and fuzzy variables). In this work, the finite-element-based probabilistic and possibilistic methods are discussed and compared. A case study of static and dynamic uncertainty analyses of a structure using the aforementioned schemes is performed. The results of those analyses suggest that the incorporation of uncertainty in the analysis provides a higher level of confidence. Moreover, they are compared for both accuracy and computational efficiency. Based on the results, it is observed that the determination of approach must be based on the problem complexity as well as the level of available information.
BOND AND SHEAR-STRENGTHENING PERFORMANCE OF FRCM COMPOSITES
Authors: Younis Adel , Ebead Usama
Published: February 2025

This paper is aimed at studying the bond and shear-strengthening performance of fabric reinforced cementitious matrix (FRCM) systems. Three FRCM systems were compared, namely, polyparaphenylene benzobisoxazole (PBO)-FRCM, Carbon-FRCM, and Glass-FRCM. At first, six double-shear specimens were tested to investigate the FRCM/concrete bond, with the test variables including the fabric type and the bond length. After that, seven shear-critical reinforced concrete (RC) beams were tested under three-point loading, considering the fabric type and strengthening configuration (full/intermittent) as the test variables. As for the double-shear test results, the failure observed was fabric/matrix debonding in carbon-FRCM, matrix/concrete debonding in PBO-FRCM, and fabric rapture in glass-FRCM. The FRCM/concrete bond increased with the bonded length, and the PBO-FRCM showed the highest bond to concrete. Regarding the RC beam tests, the FRCM-strengthened beams showed the same failure mode that is debonding at the FRCM/concrete interface. Nonetheless, FRCM had successfully strengthened the beams in shear: an average gain of 57% in the load carrying capacity was achieved as compared to the non-strengthened reference. Indeed, the full-length strengthening resulted in a better structural improvement compared to the intermittent-strengthening configuration. Amongst the three systems, carbon-FRCM systems were the most efficient in shear-strengthening RC beams.
CASE STUDY OF 3D SEISMIC PUSHOVER ANALYSIS OF INTEGRAL ABUTMENT BRIDGE
Authors: Liu Xinya , Fu Chung C.
Published: February 2025

Integral abutment bridges (IABs) have a continuous deck monolithically encased into abutment stem, and typically using single row of piles to carry vertical loads and accommodate longitudinal thermal deformation. Except for smooth pavement and low maintenance cost, IABs have also outperformed conventional seat-type abutment bridges in seismic performance due to increased redundancy, higher damping, and smaller displacements. However, lack of information on their seismic design and performance may have discouraged their use in high seismic zones. In this study, current research and implementation of IABs are comprehensively reviewed. IABs with steel-concrete girders provided by NYDOT are chosen for intensive seismic case study. Three-dimensional finite element models of IABs for nonlinear seismic analysis are elaborated to capture the behavior of components of superstructure, abutment stem, piles, backfill, etc. Pushover analyses are carried out to obtain the capacity curves. Through parametric studies, the effects of bearing are outlined. Conclusions and some recommendations are made for seismic evaluation and design practice of IABs.
STRENGTHENING OF RC BEAMS USING NEAR SURFACE EMBEDDED-FRCM
Authors: Ebead Usama , El-Sherif Hossameldin
Published: February 2025

Fibre reinforced cementitious matrix (FRCM) systems are mostly externally bonded (EB) for the strengthening of reinforced concrete (RC) and masonry structures. In this paper, the relatively new concept of near-surface embedded (NSE) FRCM, has been introduced for the flexural strengthening of beams. The process of the application of NSE-FRCM strengthening technique involves the removal of the concrete layer at beam soffit, being the most deteriorated in actual practices. Experimental evidence of the flexural strengthening efficacy of this technique is provided here. Eight RC beams were prepared and tested under four-point loading with the consideration of two test parameters: (a) FRCM material (polyparaphenylene benzobisoxazole (PBO)/carbon/ glass); and (b) the reinforcement ratio (0.5% representing flexure-deficient beams and 1.28% representing typical under-reinforced beams). The strengthening led to gains in ultimate loads that ranged between 31.4% and 84.3%.
SEISMIC DESIGN EVALUATION OF LIQUID-FILLED STIFFENED STEEL CYLINDRICAL TANKS
Authors: Roopkumdee Wiriyachai , Mamaghani Iraj
Published: February 2025

This paper aims to estimate dynamic buckling loads of cylindrical liquid storage tanks. Finite element analysis is performed using ANSYS computer program. Twelve different geometries of the cylindrical tanks are analyzed with height to diameter (H/D) ratios of 0.5, 1.0, 1.5, and 2.0 and the diameter to thickness (D/t) ratios of 1000, 1500, and 2000 to cover tall and short cylindrical tanks. The dynamic buckling capacities of cylindrical tanks filled with water up to 90% of their height are investigated in this study. The transient dynamic analysis is performed to find the dynamic buckling loads. Applied dynamic loads in this study are horizontal earthquake excitations in terms of acceleration (g) due to gravity. The transient dynamic analysis results indicate that the dynamic buckling loads decrease when the H/D ratios increase, and the dynamic buckling loads decrease when the D/t ratios increase. Design curves for the cylindrical tanks of various geometries subjected to earthquake accelerations are generated.
INCREASING THE HEIGHT OF A GUYED STEEL STACK WHICH IS SUPPORTED ON AN INDUTRIAL BUILDING
Authors: Okelo Roman , Russell Bradford
Published: February 2025

The paper studied the rehabilitation and increase in height of an existing 30 ft tall, industrial, guyed steel stack, which was built around 1977. The stack is supported on an industrial building. Stacks are an essential part of the industrial facilities. They allow the discharge of chemical waste gases from industries to the atmosphere, under stringent pollution control guidelines. The height of the stack is increased by 40 ft to comply with the new guidelines. Analytical and numerical simulations were performed using MecaStack software (local model) and SAP2000 V.20 software (global model). Analysis and design are based on the ASME STS-1-2016 standard code. Discontinuity around the manhole at the bottom of the stack is investigated with SAP2000 V.20 finite element software. Results in terms of principle stresses, and Von-Mises stress, were used to prepare recommendations, repair and construction documents for the project.
VISCOELASTIC ANALYSIS OF FLEXIBLE PAVEMENT EMBEDDED WITH CLSM BASES SUBJECTED TO SINUSOIDAL AND IMPULSIVE LOADS
Authors: Liang Yen-Chu , Wang Her-Yung , Huang Li-Jeng
Published: February 2025

This paper presents finite element analysis of 4-layered flexible pavements embedded visco-elastic asphalt concrete (AC) top layer and controlled low-strength materials (CLSM) sub-layers as well as graded crushed stone subgrades layers subjected to sinusoidal and impulsive surface wheel loads. Two-dimensional deformation assumption is employed. Time-dependent stress-strain relations are treated using Laplace transform based on correspondence principle. Scheme based on fast Fourier transform (FFT) is employed for inversion of Laplace transformed to obtain time-domain results. A typical 4-layered pavement is analyzed in which relaxation modulus of top visco-elastic asphalt layer is expressed in Prony series. Two kinds of CLSMs, i.e., CLSM-B80/30% and CLSM-B130/30% are compared with graded crushed stones and AC used for base materials. Time-domain responses of vertical displacement and stress at bottom of AC layer are compared. The vertical settlements using CLSM bases (B80/30% and B130/30%) are smaller than that using graded crushed stones even considering visco-elastic behavior of asphalt layer and show to be good materials employed as base substitutes for graded crushed stone in flexible pavement design.
FLEXURAL DUCTILITY OF STRUCTURAL CONCRETE MEMBERS SUBJECTED TO LIMITED CYCLES OF REPEATED LOADING
Authors: Oukaili Nazar , Khattab Mohammed
Published: February 2025

For structural concrete members that may expose to serious earthquake, overload or accident impact, the design of ductility must be given the same importance as the flexural strength. The aim of this investigation is to study the change in ductility of structural concrete flexural members during their exposure to limited cycles of repeated loading. Twenty full-scale beam specimens have been fabricated in to two identical groups; each group consisted of ten specimens. The first group was tested under monotonic static loading to failure and regarded as control beams, while the specimens of the second group were subjected to ten cycles of repeated loading with constant load interval, which ranged between 40% and 60% of ultimate load. Specimens in each group were categorized as follows: two traditional reinforced concrete specimens with different intensity of tension reinforcement; three partially prestressed specimens with bonded strands; three partially prestressed specimens with unbonded strands; and two fully prestressed concrete specimens. The main variable, which was considered for all specimens was the partial prestressing ratio (PPR). It was observed that, the ductility of reinforced concrete beams was insignificantly increased during subjecting to limited repeated loading. For fully prestressed and partially prestressed concrete beams with high level of PPR, the ductility was significantly enhanced, while, it was decreased for specimens with small level of PPR.
SEISMIC PERFORMANCE EVALUATION OF PILOTI-TYPE BUILDINGS AFTER AN EARTHQUAKE
Authors: Shin Hye-min , Shin Kyung-jae , Lee Su-woong , Kim Dae-geun , Lee Min-ki , Lee Jun-seop
Published: February 2025

On November 15, 2017, the second strongest earthquake occurred in Korea, which was 5.4 in size on the Richter Scale. The duration of the earthquake was short, but the damage was serious. Two recent earthquakes have shown that our country is no longer safe from earthquakes. However, to date, Korean structures are showing a low earthquake resistance, and seismic retrofitting is necessary in preparation for a large-scale earthquake. In this study, reinforcing effect of steel slit damper was analyzed based on the dynamic test results of the previously studied reinforced concrete frame. After that, push over analysis and nonlinear time history analysis using OpenSees were selected for the residential piloti-type building as the target building. In the above Korean earthquake, the damage to the piloti-type building was conspicuous. Through analysis, the vulnerable part of the piloti-type building was identified and the seismic strengthening with the steel slit damper was carried out.
SEISMIC DESIGN OF FRAME STRUCTURES EQUIPPED WITH INNOVATIVE HYSTERETIC DISSIPATIVE DEVICES
Authors: Palermo Michele , Laghi Vittoria , Silvestri Stefano , Gasparini Giada , Trombetti Tomaso
Published: February 2025

In the present work, a Performance-Based Seismic Design procedure applied to multi-storey frame structures with innovative hysteretic diagonal steel devices (called Crescent Shaped Braces or CSB) is introduced. CSBs are steel elements of peculiar geometrical shapes that can be adopted in frame buildings as enhanced hysteretic diagonal braces. Based on their "boomerang" configuration and placement inside the frame structure, they are characterized by a lateral stiffness uncoupled from the yield strength and, if properly inserted, by an overall symmetric hysteretic behavior with hardening response at large drifts, thus preventing from global structural instability due to second-order effects. The procedure here presented is intended to guide the structural engineer through all the steps of the design process, from the selection of the performance objectives to the preliminary sizing of the CSB devices, up to the final design configuration. The steps are described in detail through the development of an applicative example.
ESTIMATION OF SHEAR-WAVE VELOCITY STRUCTURE USING MICROTREMOR MEASUREMENTS
Authors: Tumurbaatar Zorigt , Miura Hiroyuki
Published: February 2025

Due to the recent construction boom in Ulaanbaatar city (UB), Mongolia, newly urban areas are rapidly expanded to the surrounded area of the city. According to the previous researches and reports, the thickness of the sedimentary basin in UB reaches 120m at the maximum in the area along the Tuul river. Therefore, the evaluation of site amplification is one of the essential parts of the estimation of earthquake hazard in this area. In this paper, the shear-wave velocity (Vs) structures in UB are estimated from single microtremor observations with the existing microtremor array observations. We carried out the microtremor observations at 50 sites and computed horizontal-to-vertical (H/V) spectral ratios. Inversion analysis is performed to the observed H/V spectral ratios based on the diffuse field approach (DFA) to determine the Vs structures. The site characterizations are evaluated from the amplification factors of the Vs structures.
STRESS INTENSITY FACTOR ANALYSIS OF AN EDGE CRACK PERPENDICULAR TO THE INTERFACE IN BI-MATERIALS
Authors: Hou Yongkang , Zhang Shuo , Duan Shujin , An Ruimei
Published: February 2025

The purpose of this paper is to investigate the stress intensity factor in the problem of a crack perpendicular to the interface in bi-materials. Based on the theory of an edge crack perpendicular to the interface between two dissimilar isotropic half-planes, the stress intensity factor was yield out from the stress singularity eigen-equation. The stress intensity factor for a composite beam segment with an edge crack under bending and tension was computed by the ordinary finite element and the singular finite element, and it was found that the singular element method is more accurate and applicable than the ordinary element method. The influence of the distance from the crack tip to the interface and the material’s mechanical properties to the stress intensity factor were analyzed. The results show that the stress intensity factor increases first, and then decreases with decreasing of the distance from the crack tip to the interface, and the stress intensity factor increases with increasing of the elastic modulus of the cracked material.
IMPROVEMENT OF REINFORCEMENT METHOD OF R/C CYLINDRICAL SHELL WITH OPENING
Authors: Hara Takashi
Published: February 2025

Reinforced concrete (R/C) chimney with a hole is prone to decrease the strength. Therefore, the particular reinforcements have been placed around the hole. Both meridional and hoop reinforcements have been placed additionally equivalent to the loss amount of reinforcements at the hole and the diagonal reinforcements have been placed to prevent the corner failures as well. Diagonal reinforcements in the shell were curved shape. It is the laborious work to place them. In this analysis, the improved reinforcement method was proposed instead of placing the conventional diagonal reinforcements. In the proposed methods, only the hoop and the meridional reinforcements were arranged around the corners instead of diagonal reinforcements. FEM analyses were done to evaluate the proposed reinforcing method. Numerical model was the cylindrical panel with a rectangular opening. From the numerical analyses, it was concluded that the R/C panel with proposed reinforcement method showed the same behavior as that with conventional reinforcement method.
STRESS STATE OF STEEL TUBE OF SQUARE CFT COLUMNS WHICH REACHED SHORT-TERM ALLOWABLE STRENGTH
Authors: Liu Mao , Handa Ryo , Kido Masae , Tsuda Keigo
Published: February 2025

The allowable strength was compared with the yield strength of CFT short columns subjected to constant axial force and horizontal force in previous studies. The yield strength of CFT columns is determined by 2/3 of compressive force of concrete in most cases. And the yield strength of CFT columns is smaller than the allowable strength. However, as an important index representing the damage state of CFT column, the stress state of steel tube when the CFT column reaches the short-term allowable strength is not clarified. The objective of this study is to make clear whether the steel tube yielded when the short-term allowable strength of square CFT column is reached by an analytical method. The analytical parameters are the effective length to depth ratio, axial force ratio and width to thickness ratio. The range of parameters in the cases which the steel tubes yield before the CFT columns reaches the allowable strength are shown and the decrease of stiffness in these cases are discussed.
ASSESSMENT OF THE TARGET RELIABILITY DEPENDING ON STRUCTURAL PROPERTIES
Authors: Ozola Lilita , Zirnova Dana
Published: February 2025

Although the establishment of the maximum acceptable failure probability for structures is not a mandatory requirement in design, it is important to develop a unified system for safety differentiation of bearing structures in public buildings so that people can feel equally safe in all the countries of the European Union. Differences from country to country in safety requirements declared by national codes may be permissible regarding the economic losses only. This study is aimed to clarify the understanding of how to examine a structure regarding the weakest link (element, fastener, system) in the limit state. In this study the authors propose a method for differentiation of structures regarding the variation of bearing capacity, which variates depending on a number of characteristics involved, and the failure mode anticipated when overloading takes place. Variation of bearing capacity is expressed in terms of reliability index variating correspondingly. Differentiation of the safety regarding failure modes anticipated has been developed using the toughness indices as a decisive criterion for the comparable assessment of structural compositions regarding the ability to sustain in the limit state for some period of time. Also, a criterion of possible redistribution of internal forces in the limit state is taken into account. The developed example of the assessment of the target reliability of structures is presented.
MECHANICAL PROPERTIES OF STRUCTURAL STEEL AND HIGH-TENSION BOLT AT ELEVATED TEMPERATURE
Authors: Shin Kyung-Jae , Lee Hee-Du , Kim So-Yeong , Chu Da-Som , Woo Jong-Hun
Published: February 2025

This paper presents the test results of the mechanical properties of three types of structural steel at high temperature, which are generally used for the Pre-Engineered Building (PEB) system. The PEB system is generally used for non-residential buildings, such as factories and warehouses. The structural steel members are installed without fire resistance protection, which means they are very weak in the case of fire. The end-plate connection could be critical in the case of fire because most of the moment is resisted by the tensile force of the bolts. Therefore, the mechanical properties of bolts at elevated temperatures are tested. Coupon test specimens for SS400(SS275), SM490(SS355), and F10T bolts were tested according to ASTM E8M. The high-temperature coupon tests were performed at 20°C, 400°C, 500°C, 600°C, 700°C, and 800°C. The test results were compared with the design reduction factors obtained from the American and European standards. The yield strength and tensile strength satisfied the minimum strength of the specified standards at 20°C. However, the reduction factor for yield strength obtained at a high temperature was lower than that of the standard value suggested by the code. In particular, the reduction factors for the high-strength bolt (F10T) were lower than those of the structural steel members (SS400(SS275), SM490(SM355)).
ANALYSIS OF BUCKLING AND BENDING FAILURE OF ALUMINIUM COLUMN SECTIONS USED IN EMERGENCY RESTORATION TOWERS
Authors: Ramji Sarah , Pasini Ciro , Chang Yongjian , Mercan Oya
Published: February 2025

This paper presents an experimental analysis of buckling and bending failure modes of a 2.58 m long, 460×460 mm2 6061-T6 Aluminum alloy column section used in emergency restoration towers. The main objective is to determine the bending and buckling load capacities of the column section through experiments, as these values are critical in an emergency tower (guyed mast) design. Within the context of this overarching goal, a secondary objective is to ascertain whether the presence of certain manufacturing non-conformance affects the loading capacity of the section significantly. Finally, finite-element analysis (FEA) simulations are conducted in order to compare the experimental data with numerical results. The results show that the ultimate bending and buckling load capacities of the column section are 383 kN and 3,868 kN respectively. Furthermore, the results indicate that the presence of manufacturing non-conformances such as air bubbles and delamination do not have a detrimental effect on the load capacity of the column. Of the two non-conformances studied, the specimen with bubbles had a 1% difference from the good specimen, and the delaminated specimen had a 10% deviation. Comparison of experimental data with FEA simulation results shows that the numerical solution tends to overestimate the stiffness of the column, and that the FEA approach may require further calibration.
A PREVENTIVE STRENGTHENING STRATEGY FOR AGED STEEL STRUCTURES
Authors: Taniguchi Nozomu , Lin Weiwei , Hiroe Masaaki
Published: February 2025

Steel columns are widely used in buildings, bridge piers, and railway platform roofs etc. With aging, those steel columns are vulnerable to corrosion and fatigue, and can deteriorate for a variety of reasons, especially in great earthquakes. In order to avoid the unrecoverable damage of existing steel columns, the high cost of the structure owners and the great impact on the public use, effective preventive maintenance methods on the aged steel piers are necessary. On this background, a strengthening method for aged steel columns by using new construction materials such as glass fiber reinforced polymer (GFRP) plates, rapid hardening concrete, rubber-latex mortar, and reinforcing bars, is introduced in this study. Depending on possible applied load directions and corrosion conditions, two specimens were used in the loading tests. Static loading tests were performed on steel columns with and without strengthening. Applied load and deflection relationship and strain distribution on original and strengthened columns were measured and compared. Moreover, three-dimensional FE models were built, and the numerical results were compared with the test results. Both experimental and numerical results indicate that the present strengthening method can significantly enhance both rigidity and ultimate load carrying capacity of aged steel columns.
EFFECT OF TRANSIENT THERMAL GRADIENT ON STRESSES IN COMPOSITE BRIDGES
Authors: Abi Shdid Caesar , El-Masri Omar
Published: February 2025

Composite steel-concrete bridges experience higher thermally induced stresses than their concrete and steel cousins. These thermal stresses which can result from support restraints, debris accumulating in expansion joints, or from non-uniform thermal gradients, can lead to significant damage in the concrete deck. Conventional heat transfer theory in solids, in three-dimensional finite element formulation, is used to perform a sequentially coupled thermal-stress analysis in a selected single-span case study bridge. Actual environmental boundary conditions for a selected geographical region are used to develop the thermal profile. The vertical thermal gradient is shown to be largely non-linear as opposed to existing models, such as AASHTO. The thermally induced tensile stresses in the concrete are shown to be significant compared to service load stresses and constitute 60% of the tensile strength of the concrete deck.
FRP-FLEXURAL STRENGTHENING OF STEEL BEAMS: A FINITE ELEMENT ANALYSIS STUDY
Authors: Regmi Bagale Bibek , Parvin Azadeh
Published: February 2025

Fiber reinforced polymer (FRP) strengthening has been widely used for concrete structures. However, limited studies have been conducted on its application to steel structures. The use of FRP materials to retrofit steel members is an effective replacement for welded or bolted steel plates and offer high strength-to-weight ratio, resilience to environmental degradation, and a robust fatigue performance. Past studies have shown that the application of FRP to steel is a promising technical solution to help against corrosion and also to increase the load carrying capacity of steel members. In the present study, finite element analysis (FEA) model of a steel beam strengthened with carbon fiber reinforced polymer (CFRP) laminates was developed using ANSYS Mechanical finite element software program. The model was validated by comparing the FEA and experimental results of an existing study in the literature and they were in good agreement. A parametric study was conducted on the validated steel beam model with the aim to investigate the effects of basalt fiber reinforced polymer (BFRP) and two types of adhesives on its performance under static loading. The FRP laminates provided an increase in flexural capacity and pseudo ductility of the beams. The optimum bond length was found to be 2/5 of the span length for the beam in this study.
MACROMECHANICAL ANALYSIS OF SPHERICALLY VOIDED BIAXIAL CONCRETE SLABS
Authors: Urgessa Girum , Ali Wondwosen , Esfandiari Javad
Published: February 2025

The use of spherically voided biaxial concrete slab (SVBS) system, which uses hollow plastic balls as infill material, has increased widely because of its reduced weight-to-strength and weight-to-stiffness ratios when compared to solid concrete slabs. However, SVBS is a heterogeneous composite structure in which building a representative continuum model poses a significant challenge. To mitigate this challenge, the feasibility of determining the macromechanical structural behavior of spherically voided biaxial concrete slabs is studied using plate theories, aided by mechanical properties that were determined from a homogenization process of the representative volume element (RVE). This paper presents numerical analysis results of SVBS using both Mindlin-Reissner (thick) and Kirchhoff-Love (thin) plate theories. The results from both theories predicted the slab behavior reasonably well and they were within 10% of each other with the exception of the prediction of the twisting moment. Possible explanation of this deviation is provided in the paper.
SEISMIC PERFORMANCE OF STRUCTURAL FRAMES AND JOINTS IN WOOD TALL BUILDINGS
Authors: Saleh Eman , Mohammadi Jamshid
Published: February 2025

There has been a growing interest in using wood in tall buildings by employing cross-laminated timber (CLT) in a structure’s moment frame system. However, still much needs to be learned about the performance of CLT frame systems subject to lateral loads such as earthquakes. The ductility needed in CLT frames in seismic load environments is primarily provided through connections. Thus, a proper connection detail is required to ensure an adequate seismic response, especially at extreme loads. Current strength specifications of connectors are mainly applicable in cases of pure tension or shear; while in real applications, connections are subjected to a combination of these loads. This paper is part of analytical and simulation studies on seismic performance of wood structural frames being conducted at Illinois Institute of Technology. These studies include simulations to investigate: (1) Moment-resistance capacity of CLT panels; and (2) Resistance capacity of typical joints used in CLT frame systems. Limited experimental data available on a 6-story wood frame system are considered as a means of verification of the aforementioned analytical investigations. Focus of this paper is specifically on the significance of interaction between tension and shear as reported in literature. Several interaction equations as implemented in current analytical models for pushover analysis of CLT frames are explained and their adequacy to predict the nonlinear behavior of CLT panels under lateral loads is discussed.
DETERIORATION OF CONCRETE SULFUR STORAGE TANK UNDER ACIDIC VAPOR ATTACK
Authors: Khalifah Hassan A. , Rahman Muhammad K. , Hamdan Omar M. , Abu Haid Mohammed , Ibrahim Mohammed , Gadhib Ali H.
Published: February 2025

Sulfur storage tanks are integral parts of refineries and gas plants. During the gas sweetening process, liquid sulfur is separated in the sulfur recovery units and is stored in underground reinforced concrete tanks in liquid phase by steam-generated temperatures of 315 °F. Roof of the sulfur pit is about 300 – 400 mm thick reinforced concrete structure with two layers of reinforcement. Inside the sulfur pit, the ceiling and walls are subjected to high temperatures and highly corrosive acidic vapors above liquid sulfur line which leads to severe deterioration of concrete and corrosion of reinforcement in the roof slab. This paper presents the NDT based investigations of the roof slab of the tank using the Ground Penetrating Radar (GPR) in a typical sulfur pit with 30 years in service. GPR survey is compared with ultrasonic pulse echo and half-cell potential measurements on the slab. Compressive strength and petrographic examination of selected concrete cores and SEM/EDS and XRD tests on powder samples, from inside the pit are presented.
PERFORMANCE EVALUATION OF VARIOUS CONCRETE MIXES SUBJECTED TO SULFURIC ACID
Authors: Rahman Muhammad Kalimur , Alkhalifah Hassan Ali , Algadhib Ali Husain , Aldulaijan Salah Othman , Barry Mohammed Salihu
Published: February 2025

Concrete is an essential structural material that has long been used for the construction of buildings, bridges, tanks, pavements and variety of the other types of structures. Due to its physical properties and economical use, concrete is used extensively in the country's infrastructure. In the Oil and Gas sector, concrete infrastructures are more challenging structures, which are exposed to a highly aggressive environment. A special type of reinforced concrete structure exposed to different forms of sulfur attack is the sulfur storage structure, typically referred to as "Sulfur Pit". Sulfur Pit is an essential part of oil and gas processing facilities, where the sulfur after extraction from the hydrocarbons in Sulfur Recovery Units is stored and maintained in the liquid phase at temperatures ranging from 130 °C to 160 °C. The gas sweeting process results in the formation of acid gas consisting of H2S, water vapor in addition to residual sulfuric acid. Reinforced concrete exposed to this environment is subject to deterioration and corrosion of the reinforcing steel. This paper presents the experimental investigation of four different concrete mixes exposed to 5% sulfuric acid at ambient temperature. These mixes include normal OPC, sulfate resistant (Type V) cement, and two mixes with supplementary cementitious materials blast furnace slag (GGBFS) and Class-F fly ash. The investigation is focused on mechanical properties and mass loss of the concrete samples.
DEVELOPING A METHODOLOGY FOR USING THE CONTINUOUS STRENGTH METHOD FOR BUILT-UP I-SECTION
Authors: Hossain Raquibul , Sakib Shadman , Alam Maleha
Published: February 2025

Built-up steel sections are widely used in the construction industry due to their wide range of compression resistance. The main objective of the study is to introduce an efficient and economic design methodology for built-up I-sections by using the Continuous Strength Method (CSM) equations. These I-sections are made from two C-sections with bolts spaced at a specific interval. This methodology includes the calculation of individual capacity of C-sections using the CSM base curve and conversion that to bolted I-sections by using I-section properties. The predicted capacities show that the modified application of CSM equations can predict compressive resistance with high accuracy for built-up I-sections. Though the effect of bolt spacing is not considered in this study, the proposed methodology paves the path for deriving CSM equations for built-up sections.
PERFORMANCE ASSESSMENT OF RC BEAM-COLUMN JOINT REINFORCED WITH DIFFERENT SUPER ELASTIC SHAPE MEMORY ALLOY TYPES
Authors: Nahar Mumtasirun , Billah A.H.M.M. , Kamal Habibur Rahman , Islam Kamrul
Published: February 2025

Superelastic Shape Memory Alloys (SE SMAs) are smart materials that have the ability to undergo large inelastic deformation upon stress removal (superelasticity) or heating (shape-memory alloy effect). If such smart materials can be used in the plastic hinge regions of reinforced concrete (RC) beam-column joints as reinforcement, they can undergo large deformations during an earthquake and can return to their undeformed/ original shape after the earthquake. This paper represents the seismic performance of beam-column joint reinforced with three different types of SMA (e.g Ni-Ti, Cu-Al-Mn, Fe based) and compared the result with regular steel-RC beam-column joint. An analytical investigation has been considered to evaluate the seismic performance of smart RC beam-column joint and regular steel-RC joint under reversed cyclic loading. The performance of the beam-column joint is compared in terms of load-story drift ratio and energy dissipation capacity. All SMA-RC beam-column joints show nearly 40-60% higher displacement than steel-RC joint before yielding. Among three types of SMA Ni-Ti dissipate 24% higher energy than any other types of SMA.
INVESTIGATION OF DAMAGE ON DERBENDIKHAN DAM DURING EARTHQUAKE EXCITATION
Authors: Mollamahmutoglu Cagri , Bedirhanoglu Idris
Published: February 2025

In this study, the performance of a damaged dam was evaluated through a three-dimensional finite element model. The dam is located in Derbendikhan city of Northern Iraq and damaged during a 7.3 magnitude earthquake which was happened 30 kilometers south of Halabja city. Derbendikhan dam which was built between the years 1956-1961 is a clay-core rock fill dam. The damage of the dam was investigated at the site right after the earthquake and some cracks were observed in the main body of the dam. The main goal of this work is to present the results of the survey which was conducted at the site and investigating the damage development mechanism through a realistic three-dimensional finite element model of the dam. As complying with the observations at the site, the finite element analysis has shown that the primary failure mechanism is due to the separation of the core and rock fill sections at the downstream side of the dam.
THE BASICS OF FIXED CONNECTION IN ANALYSIS AND DESIGN OF STEEL FRAMES
Authors: Seniwongse Muangsangop
Published: February 2025

This paper is concerned with the out-of-date design criteria in the assumption of end boundary conditions in computer analysis and design of steel building frames in some sectors of heavy industry. The two major concerns are addressed: one is the use of pinned end for the steel column base plates whose details are fixed end, and the second is the use of pinned connection design of steel beam to steel column in lieu of using moment connection. A typical frame is shown for demonstration purposes. The typical connection details used are shown. The author presents the pinned and fixed connection definition with reference to AISC Specification for Structural Steel Buildings. Examples of actual pinned end and actual fixed end are shown with reference to actual structures. A simple structure of a single column traffic sign post with a cantilever beam at the top of the column was selected to demonstrate a fixed end column base and a beam to column moment connection. It is the aim of this paper to clarify this simple but significant concept of fixed connections of column base plates and moment connection of beam to column, which in turn will lead to significant savings in the construction of steel buildings.