Steel-plate Composite Walls Research Articles

Experimental database and analysis of in-plane seismic behaviour of double steel-plate composite walls for wind power tower

A double-steel-plate composite wall (DSCW) is composed of two steel plates, infilled concrete, and connectors. Because of their superior mechanical performance, DSCWs have been widely used in engineering, especially in the field of wind power tower. However, only a few studies have been conducted on the in-plane seismic performance of DSCWs. This study focused on the in-plane seismic performance of DSCWs, and a dataset of the in-plane flexural and shear behaviours of DSCWs including over 200 specimens from more than 30 studies was built. First, various structural configurations and mechanical response parameters were adjusted to the same standard. The same parameters studied by different scholars were extracted and analysed to obtain the general rules of the influence of these parameters on the hysteresis performance of DSCWs (forward analysis), such as the distance-to-thickness ratio, axial load ratio, shear span ratio, connector type, steel plate thickness, material strength, and partition number. Second, a backward analysis using the entire database was conducted on the factors influencing different mechanical response parameters, including the failure modes, yield displacement angle, ultimate displacement angle, ductility, and energy dissipation capacity. Finally, the accuracy of the shear capacity equations in the different codes was verified using shear failure specimens from a database to provide suggestions for engineering practice.

Plasticity-based evaluation method for in-plane shear strength of steel-plate composite element

The steel-plate composite (SC) wall is considered an attractive structural type for the next generation nuclear power plants because of its efficient construction schedule, radiation shielding function, and excellent mechanical properties. During seismic action, the SC walls sustain large in-plane and out-of-plane loadings. So, it is essential for the evaluation of the in-plane and out-of-plane load carrying capacity of SC walls in design. Up to date, several equations that are developed based on elastic theory are proposed and adopted by relevant design codes. In the previous study by the authors, a lower bound equation was present for evaluation of the in-plane shear strength of SC elements based on the lower limit theorem of plastic limit theory. As a counterpart to that paper, an upper bound equation for evaluation of in-plane shear strength of SC elements based on the upper limit theorem of plastic limit theory was developed, and its minimum value solution which is the closest one to the exact solution was derived. Meanwhile, considering that concrete is not a perfectly plastic material, another equation is present to prevent the concrete between the steel faceplates from crushing prior to the steel yielding. A comparison between the results predicted by the proposed equation in this study and the test results of the SC panel specimens suggested the adequacy and accuracy of the proposed equation. In addition, comparisons of results evaluated by the proposed equations and the equations in codes JEAG 4618 and AISC N690 were also performed.

STATIC BEARING CAPACITY OF STEEL-PLATE COMPOSITE WALLS

The features of the behavior of steel-plate composite walls for static loads are considered. Based on the analysis of modern technical and regulatory documentation, the rationale for the chosen research topic is given. A review of the literature is performed, and the features of development are noted. A detailed description and features of the experimental structures under study and the materials used are presented. The features of the test are considered, and the test equipment is described. Analytical and numerical calculations of structures for eccentric compression have been performed. The description of the calculation complex and the used models of materials is presented; the description of numerical models, the features of their construction and calculation are given, the results of calculations are presented – stress distributions, deformations, features of cracking. The general types of experimental eccentric compression wall models are presented, the nature of the loss of bearing capacity of experimental structures is described, and a picture of destruction is presented. The analysis of the experimental data obtained and their comparison with analytical and numerical calculations are performed.

In-Plane Behavior of Steel-Plate Composite Wall Elements under Intermediate High Temperature

To explore how steel-plate composite (SC) walls response to in-plane loading is essential for SC structural design, especially combined with thermal loading. This work focuses on the intermediate high temperature (≤400°C) that is often considered during design process. Individual mechanical behavior of steel plate and concrete in SC walls under intermediate high temperature are studied. Thermoplasticity is applied to describe steel plate as 2D element, by which plastic flow combined with mechanical property degradation can be considered. High-temperature mechanical behavior of concrete is very complicated. In this study, strain of concrete at high temperature is decomposed into transient thermal strain, free thermal strain, and mechanical strain. By elaborating the physical meaning of transient thermal strain and selecting mathematical models for every strain component, deformation of high-temperature concrete can be calculated. To study the in-plane behavior experimentally, an SC panel test with in-plane shear and thermal loading was conducted. Steady thermal state and transient thermal state were considered in two specimens, respectively. Comparison between test data and theoretical calculation results shows good agreement. Verifications from other researchers’ tests show that the model can be applied to general situations of in-plane loading combined with intermediate high temperature.

Effects of Accident Thermal Loading on In-Plane Shear Behavior of Steel-Plate Composite Walls

Structural walls in safety-related nuclear facilities are required to be designed for seismic and accident thermal (due to postulated high-energy pipe break events) loading combination. Current U.S. and international codes provide limited guidance for analysis and design of walls for this loading combination. This paper describes the experimental results and observations from tests conducted on a laboratory-scale (1:4 to 1:5) test unit representing steel-plate composite (SC) walls subjected to combined in-plane (seismic) and accident thermal loading. The test unit was subjected to surface temperatures of up to 450°F in combination with cyclic in-plane loading. Results of similar experiments recently conducted in Japan are also summarized (with surface temperatures up to 570°F). Surface heating combined with the low thermal conductivity and high specific heat of concrete resulted in nonlinear thermal gradients through the thickness of the specimens. These nonlinear thermal gradients and the associated self- or internal restraint led to extensive concrete cracking. This concrete cracking reduced the initial and secant stiffness of the specimens. The initial stiffness of the heated specimens reduced to 30 to 40% of the initial stiffness of the control (unheated) specimen. The secant stiffness of the heated specimens reduced up to 50% of the secant stiffness of the control (unheated) specimen. However, the in-plane shear strength of the heated SC specimens was still approximately 10 to 30% greater than the nominal in-plane shear strength calculated, for the limit state of steel plate von Mises yielding, using AISC N690 equations and measured material properties. Evaluation of the experimental results and observations suggests that the in-plane shear strength of SC walls subjected to typical accident surface temperatures (up to 570°F) can be estimated conservatively using the current provisions of AISC N690. The stiffness for accident thermal loading combinations can be considered to reduce from cracked composite stiffness at ambient temperature to fully cracked—that is, steel-only stiffness as the surface temperature increases up to typical accident value.

Local buckling and axial compressive behavior of stainless-clad bimetallic steel-plate composite walls

This study investigated the local buckling and axial compressive behavior of stainless-clad bimetallic steel-plate composite (SC) walls. Stainless-clad bimetallic steel is a high-performance steel that combines the merits of both the substrate and cladding materials, showing good mechanical properties. An experimental database was compiled to evaluate the effect of normalized faceplate slenderness ratio on the local buckling and axial compressive behavior of SC walls. Experimental investigations were conducted on six stainless-clad bimetallic steel-plate composite walls with parameter of normalized faceplate slenderness ratios. Finite element models were developed and benchmarked for parametric studies. Test results and finite element analysis results were incorporated into the database. The enhanced database were utilized to evaluate the application of the current design provisions in calculating the axial compressive strength. It was found that CECS:546–2018, Eurocode 4, and AISC 360–22 cannot provide reasonable estimation of axial compression strength. Finally, a simplified equation was suggested for estimating the axial compressive strength of SC walls. The design method was conservative for both non-slender and slender steel faceplates.

Steel-Plate Composite Wall to Reinforced Concrete Wall Mechanical Connection – Part 2: In-Plane and Out-of-Plane Shear

In safety-related nuclear facilities, steel-plate composite (SC) walls are often used in combination with reinforced concrete (RC) walls or foundations. The design demands need to be transferred between the two different structural systems through appropriate connection design. A design procedure was developed by the authors, and it was evaluated by conducting two full scale tests for SC wall-to-RC wall mechanical connections subjected to out-of-plane flexure. This paper presents a brief description of the design procedure as well as the experimental and numerical investigations conducted to further evaluate the design procedure. The focus was on the performance, strength, and governing failure mode of SC wall-to-RC wall mechanical connection under in-plane and out-of-plane shear. The investigation results include global force-displacement and applied force-strain responses. The paper also presents overall damage progression in terms of concrete cracking patterns. The experimentally observed and numerically predicted results indicate that the proposed connection design procedure is suitable and conservative for SC wall-to-RC wall mechanical connections.

Steel-Plate Composite Walls Subjected to Missile Impact: Numerical Evaluation of Local Damage

Steel-Plate Composite Walls Subjected to Missile Impact: Numerical Evaluation of Local Damage

Impact response prediction and optimization of SC walls using machine learning algorithms

The dynamic impact response of steel-plate composite (SC) walls is a vital index to assess their safety. By optimizing the design parameters within the requirements of relevant specifications, the impact-induced deformation can be reduced to ensure the protection of personnel and equipment inside the structures. To process the complicated nonlinear relationship between the wall deformation and design parameters rapidly and accurately, prediction models were constructed through such machine learning algorithms as support vector regression (SVR), artificial neural network (ANN), and gaussian process regression (GPR) in this study. Then these models were further validated by the existing test results. It shows that the root mean square error (RMSE), R-Squared (R2), and the time to complete one calculation of the GPR model are 2.74, 0.9591, and 0.58 ms respectively, which has obvious advantages in terms of accuracy, stability, and efficiency among the three machine learning models. Based on the well-trained GPR model, the design of a certain SC wall in an AP1000 nuclear power plant was optimized via the genetic algorithm, with the maximum deformation and the cost of SC walls as the optimization targets. The case study shows that the optimal solution set can reduce the maximum deformation by 10.1 % while keeping the total cost constant, or reduce the total cost by 18.8 % while keeping the maximum deformation constant.

SC Wall-to-RC Basemat Over-Strength Connection: Behavior and Design

This paper presents results from experimental and analytical investigations conducted to evaluate the lateral load behavior and capacity of steel-plate composite (SC) wall-to-reinforced concrete (RC) basemat connections. Two SC wall-to-reinforced concrete basemat connection specimens were tested. These SC wall specimens had a height-to-length ratio of 0.6 and did not include boundary elements. The experimental results include the lateral force-displacement (V-Δ) responses of the specimens and observations of local damage such as steel plate local buckling and concrete crushing. 3D finite element models were developed and benchmarked using the experimental results. The benchmarked models were used to conduct analytical parametric studies, expand the database, and gain additional insights into the behavior of SC wall-to-RC basemat connections. The parameters included in analytical investigations were the wall aspect ratio (h/lw), reinforcement ratio (ρ), and wall thickness (T).

Steel-Plate Composite Wall-to-Reinforced Concrete Wall Mechanical Connection-Part 1: Out-of-Plane Flexural Strength

In safety-related nuclear structures, steel-plate composite (SC) walls are often used in combination with reinforced concrete (RC) walls or foundations. Appropriate connections are required to transfer force demands from the SC walls to the RC components without the connection failure that is often associated with brittle failure mode. This paper presents a design procedure developed for mechanical connections between SC and RC walls. This procedure implements the full-strength connection design approach in ANSI/AISC N690-18, Specification for Safety-Related Steel Structures for Nuclear Facilities, which requires connections to be stronger than the weaker of the connected walls. This paper also presents the results from experimental and analytical investigations conducted to verify the structural performance of the full-strength SC-to-RC connection. The focus of this paper (Part 1) is on the evaluation of the performance, strength, and ductility of SC wall–to–RC wall mechanical connections subjected to out-of-plane flexure. The results include global force-displacement responses, observations on concrete crack propagation, as well as applied force-strain responses of the connection region. The experimentally observed and analytically predicted results verify the conservatism of the proposed design procedure.

Non-contact lap splice connections for steel-plate composite walls - to - reinforced concrete structures

Non-contact lap splices may be considered for connecting steel-plate composite (SC) walls to conventional reinforced concrete (RC) structures. This connection type is preferred over mechanical splice connections because of perceived construction efficiency. The primary components of the non-contact lap splice connection are the steel rebars, which are fully developed in the RC structure and extended and embedded in SC walls to transfer tensile stresses to the steel faceplates. The structural performance of a non-contact lap splice connection depends on the detailing of rebars (embedment length and location relative of stud anchors) embedded in SC walls, and the design of stud anchors (spacing and size) along the rebar length. This paper presents the results of experimental investigations conducted on SC-to-RC non-contact lap splice connections to evaluate the influence of various design and detailing parameters on structural performance, failure modes, and the ability to develop full-strength connection design. Design recommendations developed previously for SC-to-RC non-contact lap splice connections were reviewed and modified based on the results of experimental investigations.

Flexural behavior of curved steel-plate composite (SC) walls under combined axial compression and cyclic lateral force

The curved steel-plate composite (SC) walls, commonly used in nuclear power plants have not been adequately investigated. This paper aims at the curvature effects on the in-plane and out-of-plane flexural behavior of SC walls with consideration of axial compression. Eight specimens were tested under combined constant axial compression force and cyclic lateral force. The failure modes, moment-drift responses, ductility, stiffness degradation, ductility and energy dissipation are reported. Finite element (FE) models using ABAQUS were established and benchmarked with test results. Results show that the curvature effect on the structural behavior of curved SC wall is insignificant. For the flexural capacities of curved SC walls with T/R ratios no more than 0.5, negligible influential factors λ due to the curvature effect are seen. For the SC walls subjected to in-plane loading, −6.9% ≤ λIP ≤ 0.0% and when under out-of-plane loading, −6.9% ≤ λOP ≤ 6.0%. The plastic in-plane and out-of-plane flexural capacities of flat SC walls considering the axial compression were derived. To modify the proposed equations and determine their limitations, a parametric study was carried out in terms of the parameters including material grades of steel and concrete, reinforcement ratios, axial compression ratios.

Flexural-capability of angle-stiffened channel-type SC wall under combined cyclic lateral-force and axial-compression

Thanks to the proven efficiency in construction schedule and great resistance to seismic and impulsive loading, the steel-plate composite (SC) walls have been widely used. When serving in nuclear power plants, the SC wall could be required to have a large wall-thickness. In that case, the angle-stiffened channel-type connectors are more feasible to link the two steel plates of SC walls compared with tie-bar type or J-hook type connectors. The reason is that the angle-stiffened embedded-channel connectors could be of larger intervals to ease the welding and concrete vibration work, meanwhile, the angle-ribs could prevent the steel plates from buckling and provide additional flexural capacities. However, the in-plane and out-of-plane flexural capabilities of angle-stiffened channel-type SC wall under combined axial compression and cyclic lateral loading have not been adequately studied. This paper presents the development and validation of finite element models (FEMs) based on the former tests, where the flexural failure of angle-stiffened channel-type SC walls is obtained under combined axial compression and cyclic lateral loading. The validated FEMs are then used for an extensive parametric study to emphasize the influence of reinforcement ratio, axial compression ratio, sectional area and distance of angle ribs, aspect ratio (or height-to-thickness ratio) and material properties on the flexural capability of angle-stiffened channel-type SC wall considering axial compression. Based on the test and numerical results, the formulas for the in-plane and out-of-plane flexural capabilities of angle-stiffened channel-type SC wall are proposed by considering the effect of axial compression and angle ribs, respectively.

Steel-Plate Composite Walls with Different Types of Out-of-Plane Shear Reinforcement: Behavior, Analysis, and Design

AbstractSteel-plate composite (SC) walls consist of two steel faceplates connected with tie bars and then filled with concrete. The tie bars provide stability to the empty modules and serve as out-...

Steel-Plate Composite Walls Subjected to Missile Impact: Experimental Evaluation of Local Damage

AbstractThis paper presents the results of an experimental program conducted to evaluate the local damage behavior of steel-plate composite (SC) walls subjected to missile impact. There is signific...

Behavior of L-joint composed of steel-plate composite wall and reinforced concrete wall

The L-joints composed of SC (steel-plate composite) walls and RC (reinforced concrete) walls are common in SC structures, while limited studies have been conducted on them. This paper experimentally and numerically investigated the behavior of SC-RC L-joint. Four large-scale specimens were subjected to cyclic loading, where the wall-thicknesses and the core region types differed. Two core region types were involved, namely the S-type and R-type, where the core region belonged to SC wall and RC wall, respectively. The test results including the test observations, failure modes, load-displacement curves and load-strain curves were reported. For providing additional insights, the finite element models were established to simulate the behavior of the test specimens. Based on the test results, the current equations for calculating the joint shear force, flexural strength of RC wall and joint shear strength were evaluated and the recommendations on the design details were made.

Experimental and numerical investigation on the L-joint composed of steel-plate composite (SC) walls under seismic loading

Although wider application of steel-plate composite (SC) walls has been seen in recent years, the investigation on the L-joints composed of SC walls is still limited. This paper focused on the seismic behavior of L-joints, where the large scale tests and numerical study were carried out. The test observations, failure modes, load-carrying capacities, load–displacement curves and load vs. strain curves of the six test specimens were reported and analyzed in detail. The benchmark finite element (FE) models to simulate the behavior of test specimens were established using ABAQUS. The parametric study including 68 models was conducted based on the benchmarked FE models. The critical parameters in the current equations for calculating the joint shear force and joint shear strength were calibrated using the FE and test results. The code equations for the flexural strength of SC wall were also evaluated by the data of the specimens with flexural failure of SC wall in the parametric study.

Seismic behaviour of flat connections between steel-plate composite (SC) walls and reinforced concrete (RC) walls

The steel-plate composite (SC) wall has been a competitive substitute for reinforced concrete (RC) wall in nuclear power plants and small modular reactors. As essential parts of the structures, the joints and connections in various shapes deserve attentions, in which the seismic behavior of flat connection between SC wall and RC wall has not been adequately studied. In this paper, four large-scale flat connections with longitudinal rebars of RC walls inserted into SC walls were tested under cyclic out-of-plane loading. Test parameters involved shear-span ratios and construction details. For specimens with small shear-span ratios, the role of shear lugs passing through the interface between SC wall and RC wall was studied. For specimens with large shear-span ratios, the necessity of mechanical splices at the ends of the inserted longitudinal rebars was concerned. The failure modes, load-strain curves and load-displacement responses of test specimens were documented. A finite element model (FEM) simulating the behavior of the test specimens using ABAQUS was established for additional insights. Based on the results, the effects of the test parameters were analyzed in detail, the load-transfer mechanism of out-of-plane bending moment was illustrated. Since the shear or flexural failure on RC wall was observed in the specimens, the design equations for the nominal shear and flexural strength of RC walls were evaluated.

Steel-Plate Composite Walls: Local Buckling and Design for Axial Compression

AbstractThis paper focuses on local buckling and axial compressive behavior of steel-plate composite (SC) walls. SC walls are comprised of a concrete wall sandwiched between two steel faceplates on...