Performance of connections adhesive-bonded for coldformed steel

In an attempt to cut the weight of the construction materials, the building industry is developing structural materials made from lightweight materials such as composites, cold-formed steel and aluminium alloys. The fabrication of these materials using traditional welding techniques is not feasible adhesive, thus bonding is at present being investigated as a potential method of connection. Limited in scope, the goal of this work was to produce adhesively bonded cold- formed steel structures to be used in the construction and to investigate the performance characteristics and failure mechanisms. The materials applied for this connection is a coldformed steel „C‟ channel section of hardened steel and epoxy adhesive. This paper reports the outcomes of mechanical tests on 18 samples of this connection. The performance of these connections is shown to depend on the comparative proportions of the bonded area. The primary conclusion is that the adhesive bonded joint gives additional strength to the connections of the subject area

Model test on the axial capacity of displacement ribbed piles

The capacity, hence the load-settlement behaviour of a pile is governed by the collective behaviour of the base and shaft. It is highly desirable, sustainable and economical to accommodate the increasing demand for deeper and wider foundations through the use of higher capacity piles. This research investigated the performance of preformed displacement ribbed piles in a unit gravity model test. Four tests were carried out to replicate the constant rate of penetration (CRP) test in the field. Two lengths corresponding to short and long piles for each of plain and ribbed piles were employed. Compacted Kaolin S300 type was employed as the model soil. The failure load of the piles was determined using six different methods. An increased capacity of 32% and 20% was obtained in the short and long ribbed piles, respectively. Also, it was observed that the closer the distance between the ribs, the higher the capacity produced for equal number of ribs. The ribbed piles gave higher capacities through the increase in their shaft capacity which is associated with the presence of ribs along their lengths. An increase in the axial capacity of displacement piles can be attained by modifying the profile of the pile shaft through the use of ribs

Seismic Performance of Steel Frames with Semirigid Connections

The nonlinear stiffness matrix method was incorporated to investigate the structural performance of steel portal frames with semirigid connections. A portal frame with unstiffened extended end-plate connection was designed to demonstrate the adequacy of the proposed method. Besides, the seismic performance of steel portal frames with semirigid connections was investigated through time history analysis where kinematic hysteresis model was assigned to semirigid connections to account for energy dissipation and unloading stiffness. Based on the results of the study, it was found that generally semirigid connections influenced the force distribution which resulted in the decrease in base shear and lighter frame compared to the rigid one. The results also indicated that there was no direct relationship between maximum displacement at the top and connection stiffness in high-rise frames

Experimental investigation on flexural behaviour with cold-formed steel cut-curved channel

This paper investigates on flexural behaviour for cold-formed steel beam. Cold-formed steel is getting popular over the years in construction industry. However, due to its thin-walled behaviour, cold-formed steel is prompt to have buckling failure. Previous research were done to provide stiffener in order to overcome this problem. Furthermore, as addressed in this paper, curved section is introduced and studied to determine its behaviour compare to straight member in handling deformation. Both straight and curved cold-formed steel were tested under flexural with different length as the investigation variable. The results were analysed for comparison. Curved section of cold-formed steel behave differently in beam and column compared to straight section. Curved section has an advantage in reducing the deflection for structural members for flexural behaviour

Slanted connection at elevated temperature under various loadings

This paper presents a detailed comparison of two types of slanted end-plate connections, under symmetric and nonsymmetric gravity loads, in terms of friction factors and angles of slanted end-plate connections. This study contributes to better understanding of roll of slanted end-plate connections under non-symmetric gravity loads on the value of the induced initial axial force due to elevated temperature in steel beams, and a comparison of the effect of symmetric gravity loads on the behaviour of such connections, before and after elevated temperature. The results imply that, before any thermal effects, a non-symmetric gravity load can be more critical than a symmetric load; the average ratio of axial force of a non-symmetric load to a symmetric load was found to be 1.49–1.57. This value was determined to be 1.64–1.90 when friction bolts instead of normal bolts were used. On the other hand, when a steel beam is subjected to a temperature increase, the amount of reaction and initial axial forces in the steel beam are not related to the type of loading. This can be considered an advantage of the slanted end-plate connection compared with a conventional vertical end-plate connection, and it could be developed in structures exposed to longitudinal movement due to expansion. The optimum angle of the slanted end-plate connection in both cases ranged from 17° to 60°

Structural performance of isolated steel beam-to-column connection

The present study attempts to determine the main characteristics of a new proposed steel connection retrofitted by an elastomeric isolator. Its stiffness, strength, and ductility are investigated. The elastomeric isolators were designed according to the Japanese Society of Base Isolation with the aim of improving the energy dissipation of the connection. Experimental tests were conducted to evaluate the moment rotation (M-θ) curve of the proposed connection as well as of fully-rigid (SidePlate) and semi-rigid (flush end-plate) connections. The behaviour of beams with flexible and fixed-end connections was also studied by classical methods of analysis. The initial stiffness and classification index of the connections were identified by an analytical calculation in compliance with the methods suggested by Eurocode 3 Part 1-8 and ANSI/AISC 360-10. The results confirmed that the new proposed connection can be classified as a flexible connection in terms of its initial stiffness; however, it developed 90% of the plastic moment capacity of a connected beam. Besides, it showed that the isolated connection did address the AISC drift angle capacity requirement of θSD for a special moment frame (SMF)

Bond behavior of the reinforcement bar in glass fiber-reinforced polymer connector

U ovom se radu prikazuje ispitivanje prianjajna i proklizavanja armaturne šipke u novorazvijenoj injektiranoj spojnici sa staklenim vlaknima (eng. glass fiber-reinforced polymer - GFRP). Ukupno dvadeset sedam uzoraka ispitano je postupnim povećavanjem osnog vlačnog opterećenja. Rezultati dobiveni ispitivanjem uzoraka usvojeni su za modeliranje ovisnosti naprezanje prianjanja - proklizavanje, što je uspoređeno sa zahtjevima iz normi i odredbi. Rezultati pokazuju da se u konusnim spojnicama razvija veća čvrstoća prianjanja i otpornost na opterećenje usporedo sa smanjenjem promjera u srednjem dijelu.This paper presents the bond stress – slip behavior of a newly developed grouted splice connection fabricated by glass fiber-reinforced polymer (GFRP). A total of twenty seven specimens were tested under increasing axial tension load. Results from the test specimens were adapted to model a bond stress – slip law to be compared with the requirements provided by design codes and provisions. The results show that by reducing mid-length diameter, higher bond strength and load capacity are generated in the tapered splice sleeves

Severe loading assessment of modern and new proposed beam to column connections

The performance of two different steel beam to column connec-tions known as SidePlateTM and a new proposed connection by seismic loading and progressive collapse were investigated in this research. Seismic performance evaluated included consideration of interstory drift angles and flexural strengths based on 2010 AISC Seismic Provisions while investigation of progressive collapse was conducted through satisfaction of acceptance criteria by rotational capacities of the connections provided in UFC 4-023-03 guideline. The results indicated that both SidePlate and the new proposed moment connection were capable of achieving adequate rotational capacity and developing full inelastic capacity of the connecting beam. Also, an excellent performance was exhibited by the con-nections in terms of keeping the plastic hinges away from the connection and exceeding interstory drift angle of 0.06 rad with-out fracture developments in beam flange groove-welded joints. Based on results, it was concluded that the SidePlate and the new proposed connection possess sufficient stiffness, strength and ductility to be classified as rigid, full-strength and ductile connections

Evaluation of extreme load performance of pre-Northridge connections

Katastrofalne posljedice djelomičnog urušavanja apartmana Ronan Point 1968. i potresa u Northridgeu 1994. razotkrile su osjetljivost čeličnih okvira izloženih ekstremnim opterećenjima. Izvješća ovih dvaju katastrofalnih događaja pokazala su značajnu ulogu priključka nosač-stup gdje su se pretežno događala oštećenja. Numeričko i eksperimentalno istraživanje provedeno je u skladu sa 2010 AISC seizmičkim odredbama i UFC 4-023-03 smjernicama. Nisko ciklično ponašanje i rotacijski kapacitet proizlaze iz analize gdje je lom u blizini sučeonog zavara bio način otkazivanja uzoraka.Disastrous consequences of a partial collapse of the Ronan Point apartment in 1968, along with the 1994 Northridge earthquake, exposed the vulnerability of steel moment frames subjected to extreme loading. The reports of these two catastrophic events revealed the significant role of the beam-to-column connection where the damage was mainly formed. A numerical and experimental investigation was conducted in accordance with 2010 AISC Seismic Provisions and UFC 4-023-03 Guideline. An inadequate cyclic behaviour and rotational capacity resulted from the analysis where the fracture in the vicinity of groove welding was due to a poorly designed connection

The chemical properties of seaweed for modify concrete

Seaweed is one of the natural sources usually use in industrial food, cosmetic, pharmaceutical and fertiliser. A natural polymer material such as seaweed is found to have excellent bonding mechanism and also the critical factor to achieve sustainability. Malaysia is also rich with seaweed species like Eucheuma Cottonii. The future study was carried out seaweed species from Malaysia especially seaweed from Sabah. This research aimed to investigate the relationship of a few chemical properties namely physical properties, metal element content, microstructure image and chemical component of seaweed type of Eucheuma Cottonii for modifying concrete. This research is mainly base on experimental works. That powdered seaweed from Eucheuma Cottonii was analysis using Energy Dispersive X-Ray (EDX), Scanning Electron Analysis (SEM) and Fourier Transform Infra-Red (FT-IR). All the procedure of the laboratory work complies with the specified and relevant standard. The research had shown that Euchema Cottonii powder content suitable for metal and component to bind together with concrete. Concrete with seaweed powder is alternative to become green construction material for sustainable concrete