Impact of Earthquake Action on the Design and Sizing of Jointed Masonry Structures in South Kivu, DRC

This article deals with the investigation of the effects of seismic impacts on the design and dimensioning of structures in South Kivu. The starting point is the observation of an ambivalence that can be observed in the province, namely the non-consideration of seismic action in the study of structures by both professionals and researchers. The main objective of the study is to show the importance of dynamic analysis of structures in South Kivu. It adopts a meta-analytical approach referring to previous researches on South Kivu and proposes an efficient and optimal method. To arrive at the results, we use Eurocode 7 and 8. In addition, we conducted static analysis using the Coulomb method and dynamic analysis using the Mononobe-Okabe method and compared the results. At Nyabibwe, the results showed that we have a deviation of 24.47% for slip stability, 12.038% for overturning stability and 9.677% for stability against punching through a weight wall.

Experimental study on the seismic performance of masonry wall reinforced by cement mortar and polypropylene band

Since masonry structures are prone to collapse in earthquakes,a novel joint reinforcement method with a polypropylene band(PP-band)and cement mortar(CM)has been put forward.Compared with the common reinforcement methods,this method not only facilitates construction but also ensures lower reinforcement cost.To systematically explore the influence of joint reinforcement on the seismic performance of masonry walls,quasi-static tests were carried out on six specimens with different reinforcement forms.The test results show that the joint action of PP-band and CM can significantly improve the specimen′s brittle failure characteristics and enhance the integrity of the specimen after cracking.Compared with the specimen without reinforcement,each of the seismic performance indexes of the joint reinforced specimen had obvious improvement.The maximum increased rate about peak load and ductility of the joint reinforced specimen is 100.6%and 233.4%,respectively.

Shaking table tests and dynamic analyses of masonry wall buildings with frame-shear walls at lower stories

This paper describes shaking table tests of three eight-story building models： all are masonry structures in the upper stories, with or without frame-shear walls of one- or two- stories at the bottom. The test results of damage characteristics and seismic responses are provided and compared. Then, nonlinear response analyses are conducted to examine the reliability of the dynamic analysis. Finally, many nonlinear response analyses are performed and it is concluded that for relatively hard sites under a certain lateral stiffness ratio （i.e., the ratio of the stiffness of the lowest upper masonry story to that of the frame- shear wall story）, the masonry structure with one-story frame-shear wall at the bottom performs better than a structure built entirely of masonry, and a masonry structure with frame-shear wall of two stories performs better than with one-story frame- shear wall. In relatively soft soil conditions, all three structures have similar performane. In addition, some suggestions that could be helpful for design of masonry structures with ground story of frame-shear wall structure in seismic intensity region VII, such as the appropriate lateral stiffness ratio, shear force increase factor of the frame-shear wall story, and permissible maximum height of the building, are proposed.

Seismic damage to structures in the Ms6.5 Ludian earthquake

On 3 August 2014, the Ludian earthquake struck northwest Yunnan Province with a surface wave magnitude of 6.5. This moderate earthquake unexpectedly caused high fatalities and great economic loss. Four strong motion stations were located in the areas with intensity V, VI, VII and IX, near the epicentre. The characteristics of the ground motion are discussed herein, including 1） ground motion was strong at a period of less than 1.4 s, which covered the natural vibration period of a large number of structures; and 2） the release energy was concentrated geographically. Based on materials collected during emergency building inspections, the damage patterns of adobe, masonry, timber frame and reinforced concrete （RC） frame structures in areas with different intensities are summarised. Earthquake damage matrices of local buildings are also given for fragility evaluation and earthquake damage prediction. It is found that the collapse ratios of RC frame and confined masonry structures based on the new design code are significantly lower than non-seismic buildings. However, the RC frame structures still failed to achieve the ＇strong column, weak beam＇ design target. Traditional timber frame structures with a light infill wall showed good aseismic performance.

Seismic collapse simulation of existing masonry buildings with different retrofitting techniques

Masonry buildings are primarily constructed out of bricks and mortar which become discrete pieces and cannot sustain horizontal forces created by a strong earthquake.The collapse of masonry walls may cause significant human casualties and economic losses.To maintain their integrity,several methods have been developed to retrofit existing masonry buildings,such as the constructional RC frame which has been extensively used in China.In this study,a new method using precast steel reinforced concrete(PSRC)panels is developed.To demonstrate its effectiveness,numerical studies are conducted to investigate and compare the collapse behavior of a structure without retrofitting,retrofitted with a constructional RC frame,and retrofitted with external PSRC walls(PSRCW).Sophisticated finite element models(FEM)were developed and nonlinear time history analyses were carried out.The results show that the existing masonry building is severely damaged under occasional earthquakes,and totally collapsed under rare earthquakes.Both retrofitting techniques improve the seismic performance of existing masonry buildings.However,it is found that several occasional earthquakes caused collapse or partial collapse of the building retrofitted with the constructional RC frame,while the one retrofitted by the proposed PSRC wall system survives even under rare earthquakes.The effectiveness of the proposed retrofitting method on existing masonry buildings is thus fully demonstrated.

Rapid report of seismic damage to buildings in the 2022 M 6.8 Luding earthquake,China

The report summarizes the observed damage to a variety of buildings near the epicenter of the M6.8 Luding earthquake in Sichuan Province,China.They include base-isolated buildings,multi-story reinforced concrete(RC)frame buildings,and masonry buildings.The near-field region is known to be tectonically highly active,and the local intensity level is the highest,that is,0.4g peak ground acceleration(PGA)for the design basis earthquake,in the Chinese zonation of seismic ground motion parameters.The extent of damage ranged from the weak-story collapse that claimed lives to the extensive nonstructural damage that suspended occupancy.The report highlights the first observation of the destruction of rubber bearings and viscous dampers in the isolation layer of Chinese seismically isolated buildings.It also features the rare observation of the brittle shear failure of RC columns in moment-resisting frames in a region of such a high seismic design requirement.Possible reasons that may have attributed to the reported damage are suggested by providing facts observed in the field.However,careful forensic analyses are needed before any conclusive judgment can be made.

Technical reports and theoretical studies about the structural behaviour of masonry domes in the 18th century

The development of the scientific theory on the stability of vaulted structures was driven mainly during the 18th century based on applying the laws of Mechanics and the knowledge of the properties of materials.In the specific case of structures such as domes,the development of the theory is closely related to the theory of arches and vaults.Still,the main contributions are made in technical reports on the construction,stability,and repair of domes,such as the dome of Saint Peter’s in Rome and Sainte-Genevie`ve or Pantheon in Paris.This article,therefore,analyses the relationship between theory and practice and the development achieved in the specific subject of masonry domes during the 18th century from the point of view of the Limit Analysis of Masonry Structures.In a more general sense,the objective of this research is to study in greater depth the theory of Limit Analysis itself,that is,to learn from the work carried out in the 18th century by mathematicians,architects,and engineers,who,although unaware of the existence of the theoretical framework of Limit Analysis as such,moved within it.

Diagnosis, seismic analysis and reinforcement of an old building in El-Maleh, Algeria

The Northern part of Algeria is considered to be the most active seismogenic area in the Western Mediterranean region. This area has a rich history of seismicity and had experienced many destructive earthquakes such as the Chlef （1954）, El-Asnam （1980）, Beni-Chograne （1994）, AYn-Temouchent （1999） and recently Boumerdes （2003） earthquakes. The earthquake of AYn-Temouchent on December 22, 1999, was of magnitude 5,7, killed at least 28 people and made thousands of families homeless. Consequent damage was seen in all the structures located in a radius of 30 kin. In the city of E1-Maleh, located 12 km northeast of Ain-Temouchent, the ＂The National Bank Branch＂ of E1-Maleh suffered moderate damage, but enough to justify questions about its safety. The project of rehabilitating this building required a broad analysis of its static and dynamic, past and present behaviors. The study reported in this paper was a necessary preliminary step toward the development of an optimal retrofit solution.

Structural performance of authentic architectural heritage designs:A masonry monument in Western Anatolia

The aim of the study is to present a multi-leveled comparative evaluation approach for structural characteristics of historic masonry monuments so that the consciousness in their authentic designs is comprehended,and the optimum structural performance is clarified.A case study approach is preferred by the examination of the Bedesten(15th‒16th centuries)located in Bergama,_Izmir,Turkey.The structure is documented through tacheometric techniques.The construction techniques of structural elements are mapped.These documented qualities are compared with similar period and/or function structures in order to rank the frequency of construction details.The geometrical factor of safety state is defined theoretically for domes and arches.Finite element macro model of the Bedesten is generated in ANSYS software and overall structural analysis of the structure is made to evaluate the safety level of historic building by the limit states through self-weight analysis.The presented study shows that the rare structural characteristics can both contribute to structural safety and cause vulnerability.Therefore,total consciousness in structural design cannot be stated for the studied Bedesten,but the structural designs that are often preferred in the monuments built at the same period in the proximity to each other have low vulnerability,yielding to conscious preferences.