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The corrosion resistance of fiber-reinforced polymer (FRP) bars and the local availability of sea sand make these materials a viable alternative to traditional reinforced concrete in the construction of islands and coastal areas. A series of central pull-out tests were conducted in this study to accurately investigate the bond performance between FRP bars and sea sand concrete (SSC) and the effect of the bond-slip relationship on the finite element (FE) analysis of FRP-bar-reinforced SSC members. A bond-slip model for the FRP bar-SSC interface was proposed to predict the bond-slip behavior between FRP bars and SSC. Numerical simulations were conducted on the pull-out specimens and an FRP-bar-reinforced SSC beam using a 3D FE model that incorporated the proposed bond-slip model. The results show that increasing the FRP bar diameter and concrete strength improves the bond properties. Sand-coating the FRP bar positively affects the bond properties. The proposed bond-slip model for the interface between FRP bars and SSC is more accurate in fitting the experimental curves than the existing models. The FE model of an FRP-bar-reinforced beam that incorporates the bond-slip model more accurately predicts the crack development, transient load reduction, and stiffness reduction after cracking than a model with a perfect bond. • The failure mechanism of the interface between FRP bars and SSC was experimentally studied. • The effect of a series of parameters on the bond behavior of FRP bar-SSC was analyzed. • A novel bond-slip model for FRP bars and sea sand concrete was developed. • Modeling a beam with the bond-slip model can more accurately predict its performance. [ABSTRACT FROM AUTHOR]

• Field and laboratory tests were conducted on concrete pipes. • The pipes sustained the field loading without any cracks. • A comparison of field and laboratory tests showed that the current field practices on concrete pipes are overly conservative. Reinforced concrete pipes are widely used under embankments for drainage purposes. Current design and construction guidelines for the reinforced concrete pipes are known to be overly conservative, putting reinforced concrete pipes at a disadvantage against flexible pipes. This study was designed to assess the structural performance of full-scale buried precast concrete pipes with shallow soil cover under the application of vehicular load representing commonly used construction equipment and daily routine vehicles. The concrete pipes incorporating fly ash were reinforced with double cage reinforcement with varying amounts of steel. Various types of vehicles including dump trucks, plain roller, asphalt-filled truck, and transit mixer were passed perpendicular to the longitudinal axis of the buried concrete pipe and the vertical displacement at the pipe's crown was monitored. Maximum deflection of 0.26 mm was observed due to the passage of dump truck over the buried pipe. No cracking or sign of distress was observed in the buried pipe under the action of tested vehicular loads. Therefore, pipes were transported to the laboratory and tested under three-edge bearing line load and patch load to mimic the application of wheel load and to investigate the cracking and ultimate capacities. The reduction in the steel reinforcement by 75 % and 50 % resulted in the decrease in the ultimate load capacities of the pipes by 83 % and 57 %, respectively. The 0.3 mm crack load in the patch load test was 0.82 to 0.89 times the 0.3 mm crack load in the three-edge bearing line load test. The 0.3 mm crack load in the laboratory test was around twice the maximum load applied to the pipe in the field buried condition. This study will help designers and contractors to better understand the field and laboratory performance of reinforced eco-friendly concrete pipes buried in shallow soil cover. Moreover, this study acts as a benchmark for evaluating the real field pipe capacities during the construction phase of various infrastructures development. [ABSTRACT FROM AUTHOR]

Construction noise is an integral part of urban social noise. Construction workers are more directly and significantly affected by construction noise. Therefore, the construction noise situation within construction sites, the acoustic environment experience of construction workers, and the impact of noise on them are highly worthy of attention. This research conducted a 7-month noise level (LAeq) measurement on a construction site of a reinforced concrete structure high-rise residential building in northern China. The noise conditions within the site in different spatial areas and temporal stages was analyzed. Binaural recording of 10 typical construction noises, including earthwork machinery, concrete machinery, and hand-held machinery, were performed. The physical acoustics and psychoacoustic characteristics were analyzed with the aid of a sound quality analysis software. A total of 133 construction workers performing 12 types of tasks were asked about their subjective evaluation of the typical noises and given a survey on their noise experience on the construction site. This was done to explore the acoustic environment on the construction site, the environmental experience of construction workers, the impact of noise on hearing and on-site communications, and the corresponding influencing factors. This research showed that the noise situation on construction sites is not optimistic, and the construction workers have been affected to varying degrees in terms of psychological experience, hearing ability, and on-site communications. Partial correlation analysis showed that the construction workers' perception of noise, their hearing, and their on-site communications were affected by the noise environment, which were correlated to varying degrees with the individual's post-specific noise, demand for on-site communications, and age, respectively. Correlation analysis and cluster analysis both showed that the annoyance caused by typical construction noise was correlated to its physical and psychoacoustic characteristics. To maintain the physical and mental health of construction workers, there is a need to improve on the fronts of site management, noise reduction, equipment and facility optimization, and occupational protection. [ABSTRACT FROM AUTHOR]

The practice of early, costly repairs or replacement buildings, which has been common in reinforced concrete construction for decades, allows the realization to mature that the reinforced concrete material for heavily exposed buildings in the infrastructure sector must be replaced by a more efficient material and its construction method. In materials research in the 21st century, the UHPC (ultra high performance concrete) has meanwhile become an obvious choice for constructive use in bridge construction and offers a wide range of options when used appropriately for the material. The construction system of the UHPC BridgefamilyIntegral is described in your design for the application of small to large bridges and thus represents a future possibility of using UHPC large prefabricated parts consistently in bridge construction. The focus is on designing material-appropriate construction. The desired target of saving both resources and CO² already in the production phase A1 to A3 should only be possible with material-appropriate construction. Another important aspect is the detailed training in order to obtain permanent bridge constructions. A system-immanent integral construction creates the prerequisites for the construction system described to be maintenance-friendly in operation. The special geometry of the construction as well as the light appearance lead to significantly lower constrained stress from load-independent effects compared to conventional bridge structures made of reinforced and prestressed concrete. In a final consideration, the advantages of this construction method are summarized again and an outlook for future applications is given. [ABSTRACT FROM AUTHOR]

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 x 250 x 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15-20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios. [ABSTRACT FROM AUTHOR]

In the framework of the ongoing EU-funded innovation project called e-SAFE (energy and Seismic Affordable rEnovation solutions), several solutions for the energy and seismic deep renovation of reinforced-concrete (RC) framed buildings in the EU countries are going to be developed and demonstrated. One of these solutions makes use of cross laminated timber (CLT) panels connected to the existing RC frame through specifically designed dampers to increase the seismic and energy performances of the existing envelope. This paper aims to preliminary assess the hygrothermal performance of such CLT panels when applied to various typical wall structures under different climate conditions in Italy through numerical simulations carried out according to the EN 13788 Standard and considering various indoor vapor production classes. Results show that the most problematic existing wall structures are uninsulated concrete walls, for which a risk of surface condensation and mold growth is predicted in all climate zones because of their low thermal resistance (U-value of 3.55 W·m-2·K-1), followed by uninsulated solid brick walls (U-value of 1.81 W·m-2·K-1). The application of CLT panels is found to not only significantly improve the thermal behaviour of the walls, but also to eliminate any surface and interstitial condensation issues in all climate zones. [ABSTRACT FROM AUTHOR]

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden. [ABSTRACT FROM AUTHOR]

Building physical and ecological potentials of buildings in timber construction Due to the high and increasing resource consumption of buildings, the construction sector is one of the major sources of environmental pollution. As a result, attention is growing for resource‐saving and sustainable materials, constructions and solutions. Timber construction methods offer numerous ecological and constructive linking points. Their specific material, constructional and manufacturing characteristics are already the subject of investigations into building physics which are currently being extended more and more to solid timber components and new impulses in processing and prefabrication technology. Within the framework of a holistic approach, this article compares the thermal, moisture and sound properties as well as the environmental quality of timber‐frame and solid timber construction elements. In comparison with reinforced concrete constructions, it is shown that the available data and methods can support planning decisions according to building physical and environmental criteria. At the same time, potentials of the construction methods become apparent, which can be realised through further development. [ABSTRACT FROM AUTHOR]

This paper presents theoretical and experimental investigations to analyze the flexural behavior of reinforced concrete beams strengthened with a cementitious mortar based on the dune sand varying the cover thickness and the reinforcement ratio. After a suitable cure of beam specimens in the laboratory, they submitted to progressive loadings until the failure. The results obtained show that the flexural capacity of the strengthened beam is about 134.44 KN, which is 96% of that of the reference beam for a reinforcement ratio of 1.2% environ (over-reinforcement section). However, for ratios of 0.5% and 0.8% environ (under-reinforcement section), the flexural peak load and the failure load of the strengthened beam and those of the reference beam are similar. Deflections of strengthened beams are in general reduced compared to those of reference beams. The repair dune sand mortar could be used to enhance the flexural capacity and the ductility of damaged reinforced concrete beams strengthened with dune sand mortars. Theoretical results compared to those obtained from experimental tests, in terms of deflections and ductility, are generally in good agreement. [ABSTRACT FROM AUTHOR]

Infill wall-frame interaction-induced damage and failure have been found in many previous earthquakes due to the inappropriate estimation of the stiffness of infill walls. It is a common knowledge of design philosophy that properly lowering the lateral stiffness of infill wall may significantly improve the seismic performances of concrete frames. Fabricated straw wall, a sandwich-type structure with tenon and groove, is proposed as a new type of lightweight and environment-friendly infill wall. The lateral stiffness is much lower than that of masonry infill wall. Shaking table tests were carried out for a concrete frame structure with fabricated straw wall, as well as for a frame with masonry infill wall for comparison. Results show that failure modes of them are different. Plastic hinges took place at the ends of beams in the frame with fabricated straw infill wall, different from the frame with masonry infill wall where the plastic hinges emerged at the ends of columns. Numerical analysis was conducted to verify and illustrate the failure mechanism. It indicates that the straw panel-infilled concrete frame well matches the design philosophy and presents better seismic performance. [ABSTRACT FROM AUTHOR]

Basic structural forms of reinforced concrete column-steel beam composite joints, such as beam- and column-through structures, are difficult to construct due to their complex structure. A joint connection construction method based on the ribbed angle steel was proposed in this study to improve construction performance of such joints, and the industrial assembly construction between reinforced concrete columns and steel beams was realized. By carrying out low cyclic loading test and numerical simulation of three full-scale specimens, the influence of beam--column section,the number of bolts between assembly connectors and steel beams on the performance of joints was examined by carrying out low cyclic loading test and numerical simulation of three full-scale specimens. Moreover, failure mode of joint was analyzed in detail and seismic performance indexes, such as bearing capacity, hysteretic performance, ductility, and energy dissipation capacity of joints, were compared. The results reveal that for different resistance matching among columns, beams, and connectors with ribbed angle steel, there are three failure modes of the joints, namely, shear failure in core area, slip at beam end, and slip at beam end with shear failure in core area. Seismic performance of joints varies with their failure modes. Hysteretic curve of shear failure joint in the core area shows evident pinch phenomenon. Ductility and equivalent viscous damping coefficients are 2.026 and 0.11, respectively. The seismic performance of the joint is consistent with that of the cast-in-place reinforced concrete beam--column joint. The hysteretic curve of the joint is full, ductility, and equivalent viscous damping coefficients reach 3.89 and 0.23, respectively, when slip exists between the connector and the steel beam. The joint demonstrates satisfactory seismic performance. This study provides an experimental basis for the engineering application of the novel prefabricated connection joint. [ABSTRACT FROM AUTHOR]

The seismic assessment of existing masonry infilled reinforced concrete (RC) building portfolios is a highly relevant issue in Italy and other Mediterranean countries, particularly in regions where a large part of the built environment was not designed according to modern seismic codes. In the past, masonry infills were generally considered as non-structural elements and were not accounted for in the design process. However, the results of experimental tests and past earthquake evidence demonstrated the influence of masonry infills on the global and local behaviour of RC buildings. Furthermore, the acknowledgment of different construction practices points out the significant variability affecting the masonry infills in terms of material properties, thickness, presence of openings and manufacturing techniques. This paper deals with the large-scale performance analysis of existing masonry infilled RC building portfolios accounting for the uncertainty related to the variability in the mechanical properties and the modelling of masonry infills. To accomplish this goal, a fully integrated building stock, representative of masonry infilled RC buildings designed according to the Italian codes in force between 1960 and 1980, was developed, using a simulated design approach. Statistical data and results of experimental tests were used to identify the main masonry infill typologies adopted in the Italian context. Detailed numerical models, whose prediction capability was appraised through the results of cyclic quasi-static tests, were developed to estimate the lateral response of the analysed RC buildings. Different response parameters, which can be easily implemented in seismic risk assessment frameworks, were considered and quantified, at the portfolio level, to understand the uncertainty propagation and impact of the masonry infills' variability on the expected performance of existing RC buildings. The results demonstrated that the variability related to the definition and modelling of the masonry infills induces significant dispersion, with respect to the mean, on the lateral response of different classes of buildings within a given portfolio. Moreover, the provided parameters for multi-linear idealised capacity curves can be used in simplified seismic fragility and risk models for existing buildings, including a proper estimate of the associated uncertainty, leading to a more accurate quantification of economic losses. [ABSTRACT FROM AUTHOR]

Seismic safety of existing reinforced concrete structures in the context of Eurocode 8 application In Germany, earthquakes represent a rare but generally possible hazard for buildings and parts thereof. The publication of the latest findings on the earthquake hazard in Germany was accompanied by a re‐evaluation of the action level in the National Annex to Eurocode 8, resulting in higher design loads in many earthquake‐prone regions. Since the introduction of normative requirements for earthquake design, the action level has increased continuously in most cases. For existing reinforced concrete structures, the question of proportionality between the protection of existing structures and the obligation to safeguard them arises for reasons of traffic safety in general, and for structural interventions due to resource‐saving revitalization in particular. Despite basically earthquake‐compliant design with ductile frames and ductile shear walls – especially with low horizontal load levels compared to the vertical load – the existing bracing systems are mostly not verifiable for the higher loads. For the range between a minimum seismic load capacity and complete seismic resistance to current actions, a risk‐based assessment using performance factors based on the Swiss SIA 269/8 is proposed. [ABSTRACT FROM AUTHOR]

BIM in repair planning The following article describes the current situation at WTM Engineers using the BIM‐software Desite (thinkproject) in projects regarding the repair of existing building structures. The usage possibilites of Desite in different planning phases are given in order to promote the digitalization progress in repair of concrete structures. Starting with the management of a 3D model of the existing structure, the software can be used to visualize damages or to plan necessary investigations of the existing structure as well as the materials used. Therefore, the implementation of essential properties has a high priority in order to create correlations between the single components and their current status. In order to ensure a successful cooperation with partners, a secure data environment muss be created. Especially with regard to the exchange of data and information between different software programs for scheduling and cost calculation. [ABSTRACT FROM AUTHOR]

The paper analyses the influence of modelling the cross-section of a beam in two-storey reinforced concrete frame of industrial warehouse with dimensions: 18.0 m × 32.0 m using bar elements on the results of bending moments, the value of elastic deflection and the dimensioning of reinforcement due to bending. Six options were considered: a beam as a rectangular section and five T-beam variants with different definitions of effective flange width. The differences in obtained results were commented on. Conclusions useful for the designing of reinforced concrete structures were presented. The procedure for determining the effective flange width in the context of PN-EN 1992-1-1:2008 and PN-B 03264:2002 standards with a commentary on the use of effective flange width in calculations and construction of reinforcement in reinforced concrete structures were described. Brief description of determining the reinforcement due to bending according to the simplified method given in PN-EN 1992-1-1:2008 was presented. In addition, the standard formula for determining the minimum cross sectional area of reinforcement (9.1N) in PN-EN 1992-1-1:2008 with a proposal for its strict determination for the T-beam with the flange in tension was analysed. [ABSTRACT FROM AUTHOR]

In this paper, a risk-based multiobjective optimal seismic design method for reinforced concrete (RC) piers is proposed. This method is used to determine the size and reinforcement ratios of piers to minimize the seismic risk of bridge systems and the construction cost of piers. The Pacific Earthquake Engineering Research- (PEER-) based probabilistic seismic risk assessment approach and the response surface method (RSM) are adopted to develop the seismic risk response surface model, which represents the relationship between the design parameters of piers and the seismic risk of bridge systems. The Pareto optimal solutions of piers are determined by applying an improved version of the nondominated sorting genetic algorithm (NSGA-II). As a case study, the proposed optimal seismic design method is applied to a continuous concrete box girder bridge. The optimal design schemes of piers according to two strategies are determined from the Pareto optimal solutions. The results show that the seismic risk response surface model can be used to accurately describe the relationship between the design parameters of piers and the seismic risk of bridge systems. The case study demonstrates the effectiveness of the proposed optimal seismic design method. The analysis of the Pareto optimal solutions allows designers to more rationally conduct the seismic design of piers. [ABSTRACT FROM AUTHOR]

Shear reinforcement, or stirrups, for reinforced masonry beams made of concrete blocks are placed inside the cells of the units. Since it is a requirement by masonry standards for shear stirrups to hook around the longitudinal reinforcement, the placement of conventional steel rebar as shear reinforcement in 200 mm (8 in.) or narrower masonry beams becomes challenging. Even the smallest size steel rebar available in Canada [10M or 11.3 mm (0.44 in.) actual diameter rebar], a standard hook detail is difficult for a mason to accommodate within field construction conditions. Hence, the current study investigated two different alternative shear stirrup configurations, namely, the use of 8-mm (5/16 in.) diameter smooth steel bars and the use of commercially available repurposed bed joint wire reinforcement. The current study showed that the masonry beams with the alternative stirrup details exhibited similar ductility as the masonry beam built with conventional steel rebar. The beam containing the bed joint wire as shear stirrups enhanced the capacity of the beam slightly more than the beams with conventional rebar and with the 8 mm (5/16 in.) smooth bar. Most importantly, the use of bed joint wire as shear reinforcement reduced crack width in a similar manner as the conventional rebar. In addition, the study found that the Canadian and American standards overestimated the shear strength of narrow masonry beams. The present study also found that the directionally based strength reduction factor (Chi factor, χ) recommended in the Canadian design standard is overly conservative. [ABSTRACT FROM AUTHOR]

From craft to customised flow production – the priority program adaptive modularised constructions made in a flux Buidling under heavy weather is seldom beneficial, but common practice on site. It promotes inaccuracies and impairs the use of modern but sensible high‐performance materials and costs time, since disruption in construction frequently causes complicated returns to the planning process. Nevertheless, a handcrafted production process is still considered the one and only alternative since all buildings are unique and thus must be manually constructed on site. Indeed? The priority program entitled "Adaptive modularised constructions made in a flux" funded by the German Research Foundation follows a completely new approach. Buildings are divided into similar modular precast concrete elements, prefabricated in flow production, quality assured, and just‐in‐time assembled on site. Comparable to puzzles with many pieces, the uniqueness of the structure is maintained. The motto is: "Individuality on a large scale ‐ similarity on a small scale". The contribution presents approaches of modularisation, production concepts, and linking digital models. Serial, stationary prefabrication enables short production times and resource‐efficient modules that are assembled to load‐bearing structures with low geometrical deviations. Stringent digitalisation ensures high quality of all intermediate steps. These comprise fabrication, assembly, and the whole service life of the structure. The result is a lean production process. [ABSTRACT FROM AUTHOR]

Cracking is a common form of damage in reinforced-concrete (RC) beams. Cracks affect the frequency and deflection of RC beams. Although a model for the natural frequencies of RC beams with one or two flexural cracks has been proposed, a study of the effect of numerous initial flexural cracks on RC beams is still lacking. In the present study, the frequency and deflection of a 60-year-old RC box beam with four initial flexural cracks were tested, and the natural frequency of the RC box beam was theoretically analysed using Rayleigh's method. Theoretical and test results showed that: (a) the natural frequency and stiffness of the RC box beam with four initial flexural cracks decreased by 39·0 and 62·8%, respectively; (b) the model for the natural frequency of the RC box beam with N initial flexural cracks was proposed based on the theoretical and test results; (c) the deflections of the RC box beam with four initial flexural cracks obtained from Branson's method and Eurocode 2 were both close to those from the test; and (d) Branson's method for calculating the deflection of beams with four initial flexural cracks was conservative. [ABSTRACT FROM AUTHOR]

This work examines the potential strengthening effect of glass fibre-reinforced polymers (GFRPs) on masonry infilled reinforced concrete (RC) frames. The experimental investigation is conducted in two stages. Initially, the behaviours of masonry infilled RC frames, including their internal interactions, lateral strength, failure modes (considering both masonry and beam-column joint failures) and ultimate failure mechanism, are characterised using six different test units. The observed behaviours are used to develop a strategy for strengthening of masonry infilled RC frames by the incorporation of GFRPs. The impact of GFRP presence on the behaviour of masonry infilled RC frames is comprehensively evaluated and the performances of GFRP-strengthened and unstrengthened structures are compared. The results demonstrate that the addition of GFRPs increases the lateral strength and stiffness significantly and alters the ultimate failure mechanism of masonry infilled RC frames. [ABSTRACT FROM AUTHOR]

Although the use of concrete and reinforced concrete for construction has been widespread, more studies are needed on marine structures exposed directly to corrosive environments to prolong their service life. This paper proposes a new type of shell precast concrete block for coastal structures, studying a beam consisting of 15mm High-Performance Glass Fiber- Reinforced Concrete (HPGFRC) at the bottom and 45mm Traditional Concrete (TC) for the rest of the structure. Steel bar reinforcements were placed at the bottom with a concrete cover of 25mm to avoid abrupt failure. The strength classes of HPGFRC and TC were 60MPa and 30MPa respectively. A reference beam consisting of TC only was also prepared for comparison. The four-point flexural bending test results showed that the first cracking strength of the proposed beam was 20% higher, as HPGFRC performed better on tension than TC. Additionally, HPGFRC's maximum strength was 25% greater than TC's. Furthermore, HPGFRC possessed more durable characteristics such as waterproof grade, abrasion resistance, and shrinkage than TC, promising to protect the reinforcement from the aggressive marine environment and corrosion, prolonging the service life of the structure. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a shake‐table test study to investigate the displacement capacity of shear‐dominated reinforced masonry wall systems and the influence of wall flanges and planar walls perpendicular to the direction of shaking (out‐of‐plane walls) on the seismic performance of a wall system. Two full‐scale, single‐story, fully grouted, reinforced masonry wall specimens were tested to the verge of collapse. Each specimen had two T‐walls as the seismic force‐resisting elements and a stiff roof diaphragm. The second specimen had six additional planar walls perpendicular to the direction of shaking. The two specimens reached maximum roof drift ratios of 17% and 13%, without collapsing. The high displacement capacities can be largely attributed to the presence of wall flanges and, for the second specimen, also the out‐of‐plane walls, which provided an alternative load path to carry the gravity load when the webs of the T‐walls had been severely damaged. The second specimen developed a higher lateral resistance than the first owing to the additional axial compression exerted on the T‐walls by the out‐of‐plane walls when the former rocked. The shear resistance of the T‐walls evaluated with the design code formula matches the test result well when this additional axial compression is taken into account. However, it must be understood that the beneficial influence of the wall flanges depends on the magnitude of the gravity load because of the P‐Δ effect and the severity of damage induced in the wall flanges when the wall system is subjected to bidirectional ground motions. [ABSTRACT FROM AUTHOR]

Load‐bearing capacity of steel profiles with tubular sections restrained in reinforced concrete If steel profiles with tubular sections are used as columns or beams, they can be restrained into foundations or walls made of reinforced concrete. These connections generally act like restraints that require a sufficient length. In the following, profiles with tubular sections restrained in reinforced concrete constructions are investigated and load‐bearing capacity verifications are treated in consideration of the restraining length and concrete compressive stresses in the restraint area, as well as verifications at the relevant points of the profiles. As a supplement to the calculation formulas, diagrams are provided that allow the determination of the restraint length. In many practical applications, the double profile diameter is sufficient as restraint length. [ABSTRACT FROM AUTHOR]

Seismic codes include strict requirements for the design and construction of mid-rise reinforced concrete residential buildings. These requirements call for the symmetric and regular arrangement of the structural system, increased cross-sections for columns, and the introduction of shear walls to counteract the effects of lateral seismic loads. It is challenging for architects to reconcile the demands of these codes with the spatial arrangement and commercial appeal of their designs. This study argues that such reconciliation is possible through an architectural analysis. First, the effectiveness of applying the seismic design principles required by the codes is demonstrated with the comparative analysis of two finite element models. Then three pairs of architectural models, representing the most common floor plan arrangements for such buildings in Turkey, are architecturally analyzed before and after the application of seismic design principles in terms of floor area and access to view. The results demonstrate that within the context defined by the methodology of this study, considerable seismic achievement can be achieved in mid-rise reinforced concrete residential buildings by the application of relatively few, basic design features by the architects. [ABSTRACT FROM AUTHOR]

The series of earthquakes that began in the area of Sisak and Banovina at the end of December 2020 and to some extent still continues caused the loss of seven lives, extensive material damage on out- and residential buildings, including many buildings with the cultural heritage status. The earthquake caused considerable economic and demographical changes, and also endangered movable cultural heritage. As the protector of written cultural heritage in the form of archival records created in this particular area the State Archives in Sisak had also faced this problem and was forced, sadly not for the first time during its 60-year history, to apply rescue measures and records protection in extraordinary conditions. The buildings in the very centre of Petrinja and Sisak built in the 18th or early 19th century already sustained considerable damage during the first earthquake of magnitude of 5 ML, which occurred on Monday, 28 December at 6:28 am. Among them is the building whose ground floor is used by the State Archives in Sisak for its Petrinja archival centre. It is a single-storey building with adapted loft, on the southern side of Petrinja’s park, built during the mid- 18th century and a valuable example of Baroque architecture. The building is owned by the town of Petrinja and the Archives has been the ground floor’s permanent user since 1966. A much stronger earthquake that occurred the next day, with its magnitude of 6.2 ML, drastically and beyond recognition changed the outlook of Petrinja’s old centre. The majority of buildings around Petrinja’s park, particularly on its east side, were almost completely destroyed. The building where Archival Remote Storage Centre Petrinja operated was not destroyed, but the structural engineer’s examination revealed that damages on the floor, stairs and roof are of such an extent that they impaired its structure and it was therefore marked as unusable. The archives space on the ground floor was thoroughly adapted in 2008 and 2009, the wooden floors with earth base were substituted with reinforced concrete slabs, which was probably one of the reasons this part of the building fared better in the earthquake. However, even though the shelves were loaded with archival records to the maximum extent, the earthquake shattered them like dominos and the records partially fell down and in some cases they fell out from archival boxes. Under the circumstances the earthquake made the Storage Centre’s further work impossible, while the state of the records meant they were no longer available for users. The notion that Petrinja’s fonds pertaining to administration are the irreplaceable source of information and documents in form of construction documentation (location, construction and occupational permits, together with design documentation) that will be essential for rebuilding the heavily wounded Petrinja dictated swift reaction and particular care during records evacuation to the Archives’ main building in Sisak. Annexed and adapted from 2004 to 2007, apart from minor damage in form of cracks on the cornerstone, outer wall of the old part of the building, the latter fared well during the earthquake. In spite of the major damage of archival shelves and mobile shelving at Sisak’s building, there was enough space for the temporary accommodation of evacuated records from Petrinja. The evacuation of the mentioned archival and library holdings from the damaged Storage Centre in Petrinja had been successfully undertaken during two workdays, on 8th and 11th January (Friday and Monday) 2021. The total of 218 fonds and 5 collections of archival records had been evacuated, taking up the total of 450 linear meters of shelves, as well as a valuable part of professional archival library in the total quantity of 80.7 linear meters. Since this undertaking required the participants to enter a space within the building that was damaged in the earthquake and hence was marked with a red label, it was carried out by the joint coordination of the Headquarters of Civil Protection, members of the Croatian Mountain Rescue Service, Croatian Army which secured some of the transport vehicles for the records, considerable efforts of the State Archives in Sisak’s employees, as well as the enthusiastic assistance of colleagues (4 employees and 2 transport vehicles) from the Croatian State Archives in Zagreb, together with numerous laymen volunteers. Even though particular care was given to the sequence of archival records within individual archival wholes, none the less it took a month following the evacuation to update the status of Petrinja’s fonds and establish order according to existing inventories. Our procedural haste was quickly vindicated by the increased intensity of users’ demands for the very same records that had been evacuated. Another aggravating factor for the activity of this institution after the earthquake was the damage on mobile shelves and ordinary archival shelves at the State Archives in Sisak’s main building. Unlike the Remote Storage Centre in Petrinja, where the shelves collapsed in domino effect, the shelves in Sisak’s repositories were laterally bent towards the wall, above the passage. The biggest damage befell shelves with the highest amount of records. Even the shelves that were ‘handmade’ in the 1960s from metal profiles 5 mm in wide were bent. It was, however, the combination of factors that caused them to become bent: their height (4 meters), being overloaded with archival records, intensity and direction of seismic waves, as well as the fact they were not mutually secured or fixated in the floor or on the celling. Except in several boxes archival records remained on the shelves without sustaining damage. Similar damage was detected on mobile shelving. The existing cross enforcements of individual shelves within the shelving proved insufficient and too weak for the intensity of the earthquake’s seismic waves, particularly with the shelves that were completely filled with archival records. The determination of damage on records that remained in buildings of individual creators remains slow and difficult due to the fact that entering the majority of buildings where records are kept is not possible or can only be done at one’s own risk because of the damages sustained by buildings. Another aggravating circumstance is the physical absence of employees in charge of records of legal entities outside archives, since they work ‘from home’ due to the pandemic. It can be concluded that the example of the State Archives in Sisak also confirms in practice that investing in construction of new buildings with reinforced concrete construction and high bearing capacity for repositories (up to 10 kN/m²) is a good and justified investment (like it was proposed by the annex and reconstruction project from 2002). While supplying repositories, particularly in potentially seismic active areas like the majority of Republic of Croatia, additional fastening of shelves should be taken into account, both horizontally (diagonally below each shelf ), which would prevent the loaded shelf to bend during earthquakes, and mutual fastenings of ordinary shelves in the shape of a cage or fixating them in the celling- or floor panel (assuming they were made from reinforced concrete). Naturally, when it comes to mobile archival shelving it is necessary to perform the mentioned fastening (in the floor or on the celling) on the fixated units, while the mobile ones should be fastened between the joined units with stronger braces than the ones currently available on the market. [ABSTRACT FROM AUTHOR]

The seismic performance of US-code conforming moment frames constructed with regularly distributed masonry infills was evaluated. Nonlinear dynamic analysis was performed considering cases with and without infills. Upon comparing these cases, it was revealed that the presence of infills causes two opposing effects on the original system-level behavior including system deformability reduction and roof drift demand reduction. When the former prevails, infilled frames were found to exhibit inferior performance relative to their bare frame counterpart, and vice versa. This leads to a conclusion that it is not always conservative to disregard influence of infills, even when they are regularly distributed. [ABSTRACT FROM AUTHOR]

Solving non‐linear optimization tasks in structural engineering – from visualization to verification of optimization results In times when climate change and nature conservation are omnipresent issues, the building industry must ask itself which measures can be used to build the structures of the future in a resource‐saving and sustainable manner. In this regard, some engineering disciplines, such as building physics and materials research, have obvious potential for optimization. Structural engineering also has great potential for optimization in the design and dimensioning of supporting structures, but the optimization methods here are highly non‐linear, complex and time‐consuming, which is why they are rarely used. A newly developed method for the visualization and verification of optimization results addresses this problem. Through the spatial representation of non‐linear relationships, the visualization provides insights that help with the classification and verification of optimization results. The new method has been tested on benchmark test problems and has proven to be a powerful tool for faster and less complicated solving of non‐linear optimization problems. [ABSTRACT FROM AUTHOR]

Optimization‐based design Concrete is freely formable. And reinforcements can be placed anywhere in the concrete. Nevertheless, this potential is rarely used. Reinforced concrete structures are commonly rectangular shaped with reinforcement meshes parallel to the surfaces and thus possess large mass. This article shows how topological optimization can be used to create concrete structures affine to the flux of forces. Material consumption decreases rapidly. External shaping, effective cross‐section designs, and trajectory‐oriented reinforcement layouts are presented. First the very basic equations of the associated structural optimization problem are derived. Then a novel material‐specific control mechanism towards tensile or compressive dominant designs is introduced. It is discussed how this enables to account for structural robustness. Numerous examples illustrate application on bridges, pylons, shells, beams, girder grids or support details and quantify the potential material reduction in concrete construction arising thereof. [ABSTRACT FROM AUTHOR]

Repair of car park ceilings with cathodic corrosion protection: investigations on the cathodic protection with separation cracks A repair of parking structures according to the repair principle of the cathodic corrosion protection (CP) can be an economic and gentle possibility to sustainably increase the remaining service life of the structure. RC ceilings frequently show separation cracks with penetrating chloride‐containing water and pitting corrosion of the reinforcement on the underside of the ceiling. This raises the question for the expert planner whether a CP system applied to the upper side of the ceiling can safely protect the corroding reinforcement on the underside. In practice it has been shown that proof of sufficient protection for this application is not trivial. This question was thoroughly examined in laboratory tests at the Institute for Material and Building Research of Munich University of Applied Sciences and in an underground parking garage. In summary of the investigations, it can be shown that the proof of the protection of the rear reinforcement in the separation crack can only be provided in a few of the investigated cases with the CP‐system installed solely on the upper ceiling side. The 100 mV criterion stipulated normatively in DIN EN ISO 12696 is too conservative for the proof of protection. However, if the proof of the 100 mV criterion is not successful, then corrosion and protective current measurements on subsequently electrically separated reinforcement areas can be considered more suitable for the proof of protection. [ABSTRACT FROM AUTHOR]

The measurement of the electrical resistance used for a non‐destructive method for reinforcing steel in concrete strained by fatigue‐relevant loading The fatigue behavior of reinforcing steel, prestressing steel and concrete has increasingly come into the focus of science in recent decades. In addition to the constantly increasing demands on, for example, bridge structures and wind turbines, which demand longer service lives and thus more load cycles, the designs of new constructions are designed increasingly filigree and slimmer. In addition, existing buildings are being converted in course of structural and social changes and are loaded with altered actions. As a result, the influence of the fatigue behavior of the materials on the structural analysis increases significantly. This work relates parts of the existing knowledge about fatigue and electrical resistance measurement to each other and presents the tests with the associated evaluation of physical values and analyses. Finally, it is stated that the electrical resistance measurement is a promising non‐destructive test method for assessing the state of fatigue phenomenon, but the measuring method still has to be optimized with regard to its faultless applicability due to secondary measurement influences. In addition, the calculations and evaluations of the fatigue tests are used to examine and compare European design standards and various test results for the fatigue behavior of reinforcing steel in more detail. [ABSTRACT FROM AUTHOR]

A lap-spliced crosstie comprises two J-shaped rebars, each with a 180° hook at one end and straight at the other end. Six large reinforced concrete columns subjected to lateral cyclic loading were tested. The results indicated the following: (1) the confining effect of horizontally lap-spliced crossties is similar to that of vertically lap-spliced crossties. (2) Splice length of the lap-spliced crossties that is smaller than the code requirement can also provide sufficient concrete confinement. (3) A method for determining required lap splice length for lap-spliced crossties is proposed. (4) The lap-spliced crosstie can considerably improve the constructability of the crossties. Furthermore, the construction quality of reinforced concrete column reinforcement and the seismic resistance capability of reinforced concrete structures can be significantly upgraded. [ABSTRACT FROM AUTHOR]