Soft Elastomeric Capacitor for Angular Rotation Sensing in Steel Components

The authors have previously proposed corrugated soft elastomeric capacitors (cSEC) to create ultra compliant scalable strain gauges. The cSEC technology has been successfully demonstrated in engineering and biomechanical applications for in-plane strain measurements. This study extends work on the cSEC to evaluate its performance at measuring angular rotation when installed folded at the junction of two plates. The objective is to characterize the sensor’s electromechanical behavior anticipating applications to the monitoring of welded connections in steel components. To do so, an electromechanical model that maps the cSEC signal to bending strain induced by angular rotation is derived and adjusted using a validated finite element model. Given the difficulty in mapping strain measurements to rotation, an algorithm termed angular rotation index (ARI) is formulated to link measurements to angular rotation directly. Experimental work is conducted on a hollow structural section (HSS) steel specimen equipped with cSECs subjected to compression to generate angular rotations at the corners within the cross-section. Results confirm that the cSEC is capable of tracking angular rotation-induced bending strain linearly, however with accuracy levels significantly lower than found over flat configurations. Nevertheless, measurements were mapped to angular rotations using the ARI, and it was found that the ARI mapped linearly to the angle of rotation, with an accuracy of 0.416∘.

Concrete-Filled Hollow Structural Sections. II: Flexural Members, Beam-Columns, Tension, and Shear

This article reviews contemporary North American and international approaches to the design of concrete-filled hollow structural section (HSS) members for flexure, axial compression plus uniaxial bending, tension, and shear. Results from tests on concrete-filled HSS members under flexure and combined loading are compared to predicted strengths using current (CSA S16:19 and AISC 360-16) and recommended CSA S16 design equations (with limits of validity). A first-order reliability analysis of design provisions for flexure is performed in accordance with CSA S408-11, and recommendations are made for potential revision of CSA S16. Design examples are provided, and results are compared to the counterpart American code (AISC 360-16). This paper is Part II of a two-part series. Part I covers materials, cross-section classification, and concentrically loaded columns.

Design of Class 4 Hollow Structural Section Compression Members

This paper presents a study on the CSA S16:19, AISC 360-16, and EN 1993-1-1 approaches to determine the nominal capacity (Cn) of Class 4 hollow structural section (HSS) compression members. Class 3 limits and effective width (be) equations are compared, and the effect of member slenderness (KL/r), width-(or diameter-)to-thickness ratio, and height-to-width (or aspect) ratio on the relative Cn predictions are evaluated. For Class 4 rectangular hollow sections, CSA S16:19 is shown to under-predict Cn by up to 34% relative to AISC 360-16. A more economical, yet still safe, method to calculate be (and hence, Cn) is proposed. For Class 4 circular hollow sections (CHS), a new method to calculate Cn utilizing the “effective area method” is proposed. This new method removes the need for having an “effective yield stress method” in CSA S16 Clause 13.3.4.

Cyclic Performance of End-Plate Biaxial Moment Connection with HSS Columns

This paper presents a numerical study on the seismic performance of end-plate moment connection between I-beam to HSS (hollow structural section) column stiffened by outer diaphragms (EP-HSS). In previous experimental research, this moment connection showed a satisfactory performance according to requirements established in Seismic provisions. However, one type of joint was studied and bidirectional and axial loads were not considered. In this since, several configurations representative of 2D interior joints and 3D interior and exterior joints in a steel building were modeled and subjected to unidirectional or bidirectional cyclic displacements according to protocol in seismic provisions. Firstly, a similar joint configuration was calibrated from experimental data, obtaining an acceptable adjustment. The assessment of seismic performance was based on hysteretic curves, failure mechanisms, stiffness, dissipated energy, and equivalent damping. The results obtained showed a ductile failure modes for 2D and 3D joint configurations with EP-HSS moment connection. The axial load has no significant effect on the moment connection. However, it affects the column strength due to the increase of the stresses in the column wall. Compared with 2D joints, 3D joints reached higher deformations even when a similar number of beams is used. The external diaphragms to the column panel zone provided rigidity in the joints and no degradation of slope for each loop in load/reload segment for elastic loop; therefore, curves without pinching were observed. All inelastic deformation is concentrated mainly in the beams. A moment resistance above 80% of the capacity of the beam at a drift of 4% is achieved in all joints. From the results reached, the use of EP-HSS moment connection with hollow structural section columns is a reliable alternative in seismic zones when steel moment frames are employed.

Weld design for hollow structural section connections: application to Canadian Standards

This article presents a comprehensive review of existing North American research on weld effective lengths for hollow structural section (HSS) connections. Data from 393 experiments and finite-element analyses is analyzed to determine the inherent reliability index (β+) of existing and proposed AISC 360 formulae for weld effective properties in axially loaded rectangular hollow section (RHS) T-, Y- and X-connections, RHS gapped and overlapped K-connections, RHS moment-loaded T-connections, and circular hollow section T-, Y- and X-connections, when used in conjunction with CSA S16-19 Clause 13.13.4.3(a) for design of welds to the ends of HSS branches. Modifications to the formulae are proposed to achieve β+ ≥ 4.0 (the target reliability index for connectors according to Annex B.4 of CSA S16-19), and recommendations are made to facilitate a “fit-for-purpose” design approach for welds to HSS. These are proposed for the next scheduled revision of CSA W59.

Development of a Test Level 4, Side-Mounted, Steel Tube Bridge Rail

A new, side-mounted, steel beam-and-post bridge rail was designed, crash tested, and evaluated according to safety performance guidelines included in the American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). The new bridge rail system was designed to be compatible with multiple bridge decks, including cast-in-place concrete slabs and prestressed box beams. Additionally, the bridge rail was designed to remain crashworthy after roadway overlays up to 3 in. thick. The bridge rail was designed and optimized based on strength, installation cost, weight per foot, and constructability. The new bridge rail consisted of three rectangular steel tube rails supported by standard steel cross section, W6 × 15 steel posts spaced at 8 ft on-center. The upper rail was a 12 × 4 × ¼ in. hollow structural section (HSS) steel tube, and the lower two rails were 8 × 6 × ¼ in. HSS steel tubes. The top mounting heights for the upper, middle, and lower rails were 39 in., 32 in., and 20 in. above the surface of the deck, respectively. A new, side-mounted, post-to-deck connection was also developed that incorporated HSS steel spacer tubes that offset the posts 6 in. from the bridge deck and aligned the face of the bridge rail with the edge of the deck. Thus, the traversable width of the bridge was maximized. Three full-scale crash tests corresponding to the MASH TL-4 testing matrix were performed on the new bridge rail. All three crash tests successfully contained and redirected the vehicles and satisfied all MASH evaluation criteria.

The Effect of Weld Length on the Tension Capacity of Hollow Structural Section (HSS)

The non-uniform stress distribution occurs in a tension member adjacent to a connection, in which all elements of the cross-section are not directly connected. This effect reduces the member’s design strength because the entire cross-section is not fully effective in the critical section’s location. That's why an experimental study has been done to investigate the effect of the weld length on the tension capacity, two specimens (hollow structural sections) have been tested by using Instron 8800 machine with two weld lengths, 46 mm and 56 mm. The 46 mm size is the minimum requirement of the sufficient size of the tension connection depending on United States Steel Standard. The Result proved that there has been too much effect on the connection carrying tension capacity. The result of the 46 mm weld length is about 155 KN and about 180 KN for the 56 mm weld length. While the ABAQUS simulation results were about 168 KN for the 46 mm weld length and about 172 KN for the 56 mm weld length.