An improvement's project model to foster sustainable continuous improvement

Continuous Improvement programs are constantly applied amongst companies to reach competitive advantages. However, it is known that companies struggle to sustain benefits of continuous improvement projects in long-Term periods. Indeed, there is not a common shared framework assessing which are the managerial variables that can guarantee improvement's projects success. This research presents a model and a pool of improvement's projects could be framed and carried out accordingly. The model and its enabler mechanisms foster the importance that the outstanding literature assign to human focused factors and soft practices to sustain continuous improvement benefits in the long-Term period. This study presents a first assessment analysis of the model, even if not statistically valid, highlighting its enablers and barriers for a correct application. Then, based on the first data collected on a sample of improvement's projects framed with the model described, the study draws some considerations about which are the critical success factors for improvement's projects

An optimization-based rigid block modeling approach to seismic assessment of dry-joint masonry structures subjected to settlements

A rigid block modeling approach is presented for rocking dynamics and nonlinear static analysis of dry-joint masonry structures subjected to settlements and earthquake excitations. For the different types of analysis, a unified optimization-based formulation is adopted, which is equivalent to the system governing the static and dynamic structural response. Sequential solution procedures are used for time integration and for pushover analysis which take into account the effects of large displacements under the combined action of support movements and lateral loads. No-tension elastic contacts with finite shear strength are considered at block in-terfaces for time-history analysis and to obtain the elastic branch of pushover curves in nonlinear static analysis. A unilateral rigid contact behavior is also considered to obtain the descending post-peak branch of pushover curves corresponding to the activation of the rigid-body rocking motion, according to displacement-based assessment methods of failure mechanisms adopted in the standards. Comparisons with numerical models and experimental tests on a rocking block and on a buttressed arch are presented to show the accuracy of the developed approach. Simple tests on dry-joint tuff panels on the tilting table were also carried out to show the effects of imposed movements at support on the response to lateral loads. Finally, an application is presented to a full-scale triumphal arch subjected to the combined action of support movements and earthquake excitation to discuss, on the basis of the developed model, the effects of settlement-induced damage on seismic performance. The numerical analyses showed that the lateral force, the displacement capacity and the rocking response can be significantly affected by support movements, pointing out the relevance of the current building condition in the seismic safety assessment.- The financial support of the research project DPC-ReLUIS 2022-2024: Work Package 5 "Integrated and low-impact strengthening interventions" funded by the Civil Protection Department IT (Grant no. 897-01/04/2022) is acknowledged. The authors are grateful to Prof. Chiara Calderini from the University of Genova for providing data from the experimental tests on the arch-pillars system investigated in the manuscript. The authors are also grateful to Mr. Domenico Imperatrice from the Department of Structures for Engineering and Architecture for his assistance and support throughout the experimental investigation on the wall panels subjected to support movement and lateral loads

Cultural Heritage Exposed to Natural Hazards: the Case Study of the Convent of San Domenico in Maiori

Nowadays it is widely recognized that structural interventions on cultural heritage buildings shall comply with the minimum intervention principle. The main goal is to enhance the structural capacity respecting, at the same time, the authenticity of the monument. As such, the correct interpretation of the current damage is a first fundamental step in the design of an efficient structural intervention. Within this framework, the paper presents the results of an in depth investigation carried out to assess the structural capacity of a complex monument affected by several deficiencies. The case study is the convent of Saint Domenico, a seventeenth century’s masonry structure, belonging to the traditional architectural typology of the court building. The building is located in Maiori, a small town in the Amalfi Coast (Italy), included in the UNESCO World Heritage List since 1997 for its great cultural and naturalistic interest. The structure was abandoned during the 80s, and currently presents an extensive and diffuse crack pattern that is the consequence of several causes such as: the natural aging of material, the lack of maintenance, the modifications occurred during the centuries, the seismic events occurred in the past and the poor quality of the foundation soil. In this paper, starting from the knowledge acquisition path of the whole Convent, a special focus on the structural behavior of the East wing is provided. A numerical model of a cross section of the wing has been developed and analyzed considering the effects of lateral loads and settlements. The numerical analyses are carried out using LiaBlock_3D, an in-house software tool for the limit equilibrium analysis of rigid block assemblages. Results of the analyses are discussed in details and a comparison with the actual crack pattern of the structure is provided as well

Cultural Heritage Exposed to Natural Hazards: the Case Study of the Convent of San Domenico in Maiori

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Masonry macro-block analysis

The structural analysis involves the definition of the model and selection of the analysis type. The model should represent the stiffness, the mass and the loads of the structure. The structures can be represented using simplified models, such as the lumped mass models, and advanced models resorting the Finite Element Method (FEM) and Discrete Element Method (DEM). Depending on the characteristics of the structure, different types of analysis can be used such as limit analysis, linear and non-linear static analysis and linear and non-linear dynamic analysis. Unreinforced masonry structures present low tensile strength and the linear analyses seem to not be adequate for assessing their structural behaviour. On the other hand, the static and dynamic non-linear analyses are complex, since they involve large time computational requirements and advanced knowledge of the practitioner. The non-linear analysis requires advanced knowledge on the material properties, analysis tools and interpretation of results. The limit analysis with macro-blocks can be assumed as a more practical method in the estimation of maximum load capacity of structure. Furthermore, the limit analysis require a reduced number of parameters, which is an advantage for the assessment of ancient and historical masonry structures, due to the difficult in obtaining reliable data

Shake-table testing of a stone masonry building aggregate: overview of blind prediction study

City centres of Europe are often composed of unreinforced masonry structural aggregates, whose seismic response is challenging to predict. To advance the state of the art on the seismic response of these aggregates, the Adjacent Interacting Masonry Structures (AIMS) subproject from Horizon 2020 project Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe (SERA) provides shake-table test data of a two-unit, double-leaf stone masonry aggregate subjected to two horizontal components of dynamic excitation. A blind prediction was organized with participants from academia and industry to test modelling approaches and assumptions and to learn about the extent of uncertainty in modelling for such masonry aggregates. The participants were provided with the full set of material and geometrical data, construction details and original seismic input and asked to predict prior to the test the expected seismic response in terms of damage mechanisms, base-shear forces, and roof displacements. The modelling approaches used differ significantly in the level of detail and the modelling assumptions. This paper provides an overview of the adopted modelling approaches and their subsequent predictions. It further discusses the range of assumptions made when modelling masonry walls, floors and connections, and aims at discovering how the common solutions regarding modelling masonry in general, and masonry aggregates in particular, affect the results. The results are evaluated both in terms of damage mechanisms, base shear forces, displacements and interface openings in both directions, and then compared with the experimental results. The modelling approaches featuring Discrete Element Method (DEM) led to the best predictions in terms of displacements, while a submission using rigid block limit analysis led to the best prediction in terms of damage mechanisms. Large coefficients of variation of predicted displacements and general underestimation of displacements in comparison with experimental results, except for DEM models, highlight the need for further consensus building on suitable modelling assumptions for such masonry aggregates

The use of labour flexibility for output control in workload controlled flow shops: A simulation analysis

Workload control theory seeks to align capacity and demand to improve delivery performance. However, workload control researchers mainly focused on input control, which regulates the input of work to the production system, thereby neglecting output control, which uses capacity adjustments to regulate the outflow of the work. Moreover, few existing studies on output control investigate a temporarily increase in capacity. This paper introduces a new search direction for output control which does not require an increase in capacity – labour flexibility. Idle operators can move from their workstation to another, thus temporarily increasing the output of that workstation without extra capacity. Using simulation of a five workstations flow shop line, we highlight the positive performance effect of labour flexibility. However, this comes at the cost of high labour movement. Introducing a load-based constraint on when workers are allowed to move significantly reduces labour movement, while realizing most of the performance improvement observed for unconstrained labour movement. This has important implications for future research and practice

Integration of order review and release and output control with worker's allocation in a pure flow shop

With the increase of competitiveness and customer customization requirements, companies' capability to predict and shorten lead-time is becoming an order winner factor. This is particularly crucial for high variability mix and low volume make-to-order companies. Production Planning and Control aims at the alignment between capacity and demand in order to improve production system performance along with lead-time reduction. Workload control is a planning production and control concept developed for high-variety low-volume companies. It aims at controlling the workload in the system by mean of two mechanisms: the input control and the output control. The former regulates the release of new orders in the system, while the latter controls the production capacity. Most of the existing studies focused only on input control, while the output control has been quite overlooked. Moreover, the few studies that combine the two controls were interested in showing the effect on performances and did not consider a specific output control strategy: they operationalized capacity adjustments as decreases of the processing time. This paper is a preliminary step in filling this gap: input control in the form of order review and release and worker's allocation, as capacity adjustments strategy, are integrated in a pure flow shop. Worker's allocation is meant not to increase the overall capacity of the system but to shift idleness periods of workers. Order review and release and Output Control integration (ORROCI) model is presented, showing how the two control mechanisms can be integrated and tested, through simulation. It takes into account both load distribution and capacity available in the system and it transfers workers only when there are imbalances amongst stations load. Preliminary results show that order review and release and worker's allocation can be successfully integrated, achieving superior performances. Further researches can be pursed testing different labor flexibility and efficiency levels, along with different where, when and who rule concerning worker's allocation

Rigid block modelling of historic masonry structures using mathematical programming: a unified formulation for non-linear time history, static pushover and limit equilibrium analysis

A unified formulation is presented for non-linear time history, static pushover and limit analysis of historic masonry structures modelled as 2D assemblages of rigid blocks interacting at no-tension, frictional contact interfaces. The dynamic, incremental static and limit analysis problems are formulated as mathematical programming problems which are equivalent to the equations system governing equilibrium, kinematics and contact failure. Available algorithms from the field of mathematical programming, contact dynamics and limit analysis are used to tackle the contact problems between rigid blocks in a unified framework. To evaluate the accuracy and computational efficiency of the implemented formulation, applications to numerical case studies from the literature are presented. The case studies comprise rigid blocks under earthquake excitation, varying lateral static loads and sliding motion. A set of two leaves wall panels and an arch-pillars system are also analysed to compare failure mechanisms, displacement capacity and magnitudes of lateral loads promoting the collapse