Research on Earthquake Load Analysis of Large Structures in Non-Slide Construction

The determination of wind‐induced fatigue load in large structures and buildings with complex geometries, which do not fall in typical cases of building codes and standards, represents a consuming task, and it is usually evaluated through the aid of wind tunnel tests, while computational approaches do not yet have a large application.The practical use of computational fluid dynamics (CFD) techniques in civil engineering applications has in fact been rare outside the framework of steady‐state analyses, because of the limitations of RANS approaches and of the higher cost of LES, but with the increase in computing resources and with the introduction of new and more efficient turbulence models, the practical use of CFD to evaluate fluctuating features of wind flow is much more feasible now. With it, it is possible to foresee the possibility for the evaluation of wind‐induced fatigue loads in steel structures by using CFD. This paper has the purpose to discuss the feasibility of a procedure that uses CFD as the first step in a chain of numerical simulations that leads to the fatigue calculation of a large, complex structure.The state of the art of turbulence models for CFD is here shown by performing literature review, with particular attention to their application to case studies related to large steel structures. A special focus in this paper lies in the use of PANS models, which reduce computational cost and grid sensitivity compared with LES, while providing comparable accuracy.

Purpose To analyze the dynamic response of the lumbosacral vertebrae structure of a scoliosis spine and a kyphosis spine under whole-body vibration. Methods Typical Lenke4 (kyphosis) and Lenke3 (scoliosis) spinal columns were used as research objects. A finite element model of the lumbosacral vertebrae segment was established and validated based on CT scanning images. Modal, harmonic response, and transient dynamic analyses were performed on the lumbar-sacral scoliosis model using the finite element software abaqus. Results The first four resonance frequencies of kyphosis spine extracted from modal analysis were 0.86, 1.45, 8.51, and 55.71 Hz. The first four resonance frequencies of scoliosis spine extracted from modal analysis were 0.76, 1.45, 10.51, and 63.82 Hz. The scoliosis spine had the maximum resonance amplitude in the transverse direction, while the kyphosis spine had the maximum resonance amplitude in the anteroposterior direction. The dynamic response in transient analysis exhibited periodic response over time at all levels. Conclusion The scoliosis and kyphosis deformity of the spine significantly complicates the vibration response in the scoliosis and kyphosis areas at the top of the spine. Scoliosis and kyphosis patients are more likely to experience vibrational spinal diseases than healthy people. Besides, applying vertical cyclic loads on a malformed spine may cause further rotation of scoliosis and kyphosis deformities.

The current physical pre-assembly method of large steel structures is time consuming and costly and requires large sites. Thus, the pre-assembly of large steel structures in a virtual way, starting from building information modeling (BIM), is an interesting alternative to the physical one. In this study, an innovative method for virtual pre-assembly is proposed on the basis of BIM, plane-line-point algorithm, and 3D measurement. This method determines the optimal analytical least squares of the various built components. The technique verifies the feasibility of the steel structure assembly and the fulfillment of the design geometries, starting from the real data obtained by an accurate metric survey of the fabricated steel elements. The method is applied to a real case, and obtained results largely satisfy the prefixed research objectives. Suggestions to improve the proposed method are also discussed.

PurposeThe purpose of this study is to address the welding demands within large steel structures by presenting a global spatial motion planning algorithm for a mobile manipulator. This algorithm is based on an independently developed wall-climbing robot, which comprises a four-wheeled climbing mobile platform and a six-degree-of-freedom robotic manipulator, ensuring high mobility and operational flexibility.Design/methodology/approachA convex hull feasible domain constraint is developed for motion planning in the mobile manipulator. For extensive spatial movements, connected sequences of convex polyhedra are established between the composite robot’s initial and target states. The composite robot’s path and obstacle avoidance optimization problem are solved by constraining the control points on B-spline curves. A dynamic spatial constraint rapidlye-xploring random trees-connect (RRTC) motion planning algorithm is proposed for the manipulator, which quickly generates reference paths using spherical spatial constraints at the manipulator’s end, eliminating the need for complex nonconvex constraint modeling.FindingsExperimental results show that the proposed motion planning algorithm achieves optimal paths that meet task constraints, significantly reducing computation times in task conditions and shortening operation times in non-task conditions.Originality/valueThe algorithm proposed in this paper holds certain application value for the realization of automated welding operations within large steel structures using mobile manipulator.

This research studies the effect of treating sandy soil with steel slag under seismic action (El Centro, Kobe) because of the present increase in seismic effectiveness and going to minimize damage of the foundations by excessive settlement. Steel slag was added to sandy soil with three percentages (3%, 6%, and 9%) and compacted with a relative density of 56%, and 77%. The prepared soil samples were tested on a shaking table (vibrating table). Settlement occurs due to dynamic force. A circular foundation with a diameter of 100 mm and a thickness of 40 mm was used, and the applied load was constant at 3.81kg. When the earthquake accelerates more, it results in increased settlement of the circular foundation based on sandy soil, in a dry or saturated state. The settlement of the foundation increases when subjected to the El Centro and Kobe earthquakes. In addition, increasing the mixing ratios and relative density decreases the settlement of the foundation subjected to earthquake. As the mixing ratio increased to 9%, the settlement ratio decreased. In the dry state, the settlement decreased by (37.42% and 36.77%) at a relative density of 56% for the El Centro and Kobe respectively. At a relative density of 77%, the settlement rate decreased by (39.31% and 39.89%), respectively. In the saturated state, the settlement decreased by (28.05% and 22.92%) at a relative density of 56% for the El Centro and Kobe respectively. At a relative density of 77%, the settlement rate decreased by (31.87% and 25.17%) for the El Centro and Kobe respectively. The settlement for the saturated state was twice that for the dry state.

Simulation of dynamic environments for design verification

Collapse of the spatial double-layer cylinder shell by experimental study

With the continuous development of the Chinese economy and the rapid development of large public buildings, the application of steel structures in large buildings is gradually increasing. The use of steel structures is crucial for meeting the needs of large-span, super high-rise buildings, rapid construction, and achieving sustainable development of buildings. Therefore, studying and analyzing the construction technology of large-scale building steel structures has important practical significance. This study is based on a library construction project, focusing on the installation of embedded bolts, steel columns, steel beams, and high-strength bolts in the construction of large building steel structures, as well as the technical schemes and construction processes of welding, anti-corrosion coatings, and fireproof coatings. I hope to provide reference and suggestions for actual construction.

The use of direct embedded prestressed concrete poles for the support of substation equipment and electrical bus conductors is potentially a very cost-attractive alternative to steel substation structures supported on cast-in-place foundations. The analysis of substation structures requires consideration of the structural response to electromagnetic forces due to short circuits (shock loads) especially for the case of rigid bus support structures. In this study, the dynamic response of prestressed concrete pole substation structures is compared to the response of more traditional steel substation structures. A dynamic factor is suggested to consider the impact effect on these structures. A proposed testing method to verify the theoretical results by applying a shock load to the substation structure is also presented.

Chapter 8 - Modal and Transient Dynamic Analysis

A force-based fiber beam-column element is proposed for the capacity assessment of frame structures under high shear. The proposed element is suitable for the performance assessment of large scale steel structures, which are not flexure-dominated. The element formulation follows the assumptions of the Timoshenko beam theory, while its kinematics are obtained through the natural-mode method. The element state-determination phase, instead of uniaxial material laws, typically associated with fiber elements, is based on a three-dimensional law taking into consideration the interaction between axial, bending, shear and torsion. Numerical examples are presented confirming the accuracy and the computational efficiency of the proposed formulation under monotonic, cyclic and dynamic/seismic loading. Compared to experimental results and the results of detailed finite element models, excellent agreement is achieved.

In many countries, inland waterway transport plays a significant role in the overall transport system. Navigation locks and dams are critical for inland waterways which regulate water and allow vessels to navigate. These infrastructures normally utilize large hydraulic steel structures, which are primarily of welded steel structures. Many of the critical welded joints of navigation lock gates have been in service for decades and are experiencing varying degrees of deterioration, mainly from fatigue. Inspection and maintenance of lock gates are expensive, generally requiring the complete closure of locks. Therefore, innovative strategies for the inspection and maintenance of lock gates are required. Fatigue cracks reflect the inherently poor fatigue performance of welded joints. Due to the cyclic loading nature of lock gates the fatigue of critical details requires assessment methods based on the reliability methods. Risk-based inspection planning are used for marine structures but seldom applied to inland navigation lock gates. This paper presents methods to update the failure probability of welded joints considering crack inspection data by using Dynamic Bayesian Network. Optimal inspection and repair plans can be evaluated by risk analysis, combining failure probabilities and associated expected costs for different events. In this study, a numerical example of the procedure of risk-based maintenance of a lock gate based on multiple critical welded joints is described. This reference case is a lock gate fabricated with five critical welded joints corresponding to different equivalent stress ranges. The conclusion is that risk-based maintenance of lock gates based on the optimization of the total expected cost is recommended.

Through the use of active controllers, a structure can modify its behavior during dynamic loadings such as impact, wind, or earthquake loadings. Such structures with self-modification capabilities are called smart structures. The smart-structure technology will have enormous consequences in terms of preventing loss of life and damage to structure and its content specially for large structures with hundreds of members. In this paper, a computational model is presented for active control of large adaptive structures subjected to dynamic loadings such as impact, wind, and earthquake loadings. The governing differential equations of the open-loop and closed-loop systems are formulated, and a recursive approach is presented for computing the response of the structure. A robust parallel-vector algorithm is developed for the recursive solution of the response of the open-loop and closed-loop systems. The computational model is applied to active control of large bridge structures. Three different schemes are investigated for optimal placement of controllers in bridge structures. Results are presented for three types of bridge structures: single-span, multispan continuous, and curved steel-truss bridges.

Impacts of soil-structure interaction on the structural control of nonlinear systems using adaptive control approach

The redesign of the Sophos School Indonesia, BSD School Building was carried out using a steel structure with a Special Moment Resisting Frame (SRPMK) system in accordance with SNI 1726:2019, SNI 1727:2020, and SNI 1729:2020. This study aims to determine the dimensions of the steel profile and evaluate the structural performance against earthquake loads and other loads through the Load and Resistance Factor Design (LRFD) method with ETABS software. The object of the study is a 4-story school building with a height of 19.55 m with a span of 28.8 m × 18 m and a main structure of BJ-41 quality steel beams and columns. The loads calculated include dead, live, wind, and earthquake loads. The analysis results show that the steel profile used meets the safety requirements, with mass participation achieved in the 18th mode, maximum inter-story drifts of 39.472 mm (X) and 34.639 mm (Y) which are still below the SNI limit, and the P-Delta effect shows a stability ratio <0.1. Thus, this four-story school building is feasible to be built using a steel structure with the SRPMK system, which meets Indonesian earthquake resistance standards.