Category: Masonry

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Report # 173 : Brick Masonry Construction in Pakistan

by Sarosh Hashmat Lodi, Abdul Jabbar Sangi, Adam Abdullah

This report provides an overview of brick masonry housing construction, which constitutes 62.38% of the total built environment of Pakistan. Brick masonry construction ranges from typical one storey houses which are common in rural areas up to three-storey buildings (common in urban areas). Buildings of this type are generally constructed without seeking any formal engineering input. Due to inherent weaknesses in the structural load carrying system and also to the usage of poor quality construction materials, this construction type has performed extremely poorly during recent earthquakes in Pakistan. Due to the lack of specific construction guidelines and the applicable building permit laws to regulate such construction techniques, an overwhelming percentage of existing as well as newer building stock is now under an increased seismic threat.
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Report # 175 : Reinforced Clay Brick Masonry Building

by Luis Carlos Hackmayer, Lars Abrahamczyk, Jochen Schwarz

This type of single-story housing is typically built in urban areas around the Country. Nowadays also
multistory buildings up to 10 stories can be found with the same structural system and is generally
used for residential purposes; however this report focuses on single-story buildings. This type of
structure is in general earthquake resistant but the construction process should be somehow improved
in terms of controls and checks. The vertical and horizontal loads are supported by the reinforced
masonry walls. The vertical reinforcement bars are placed in the hollow cores of the clay masonry
units and the horizontal reinforcement bars in between the horizontal bed joints of the units (the
separation depends on the selected energy dissipation capacity).

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Report # 172 : Dry Stone Construction in Himachal Pradesh

by Ankita Sood, Aditya Rahul, Yogendra Singh, Dominik H. Lang

The addressed building type has been identified in Himachal Pradesh, a northern state in India. It is a
relatively recent construction typology, which can be seen prevalent in the areas where people have
been forced to leave their traditional construction practices due to scarcity of wood. Thus, this
construction style is nothing but the traditional housing style omitting the wooden elements, be it
Kath-Kunni style of the Kullu, Shimla or Kinnaur districts or Thathara style of Chamba district. Due
to the region’s heavy precipitation both in terms of rainfall (June to July) as well as snowfall (October
to March), rubble stones are preferred over the alternative locally available construction material, i.e.
mud. However, these buildings possess high seismic vulnerability due to low in-plane and out-ofplane
strength of their dry stone walls. This report identifies the main sources of seismic vulnerability
of dry stone buildings and also suggests a retrofitting scheme to reduce the seismic vulnerability of
such buildings.

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Report #174 : Concrete-block masonry construction in Pakistan

by Sarosh Hashmat Lodi, Abdul Jabbar Sangi, Adam Abdullah

This report provides an overview of concrete block masonry housing construction, which is generally found in urban areas of Pakistan. Block masonry covers 3.3% of the total built environment of Pakistan. Block masonry construction is the most common type in less developed urban areas, where clay is not readily available, and ranges from one-storey houses to multi-storeyed buildings. The construction is generally carried out without any technical input. There are no guidelines and laws available to regulate it; therefore, it suffers from a number of weaknesses. This construction type is highly vulnerable to seismic forces.

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Report # 167 : Reinforced concrete buildings with masonry infills

by Sarosh Hashmat Lodi, Abdul Jabbar Sangi, Adam Abdullah

This report provides an overview of reinforced concrete buildings in Pakistan, which are mainly limited to urban regions of the country. Reinforced Concrete buildings cover only 7.64% of the total built environment of Pakistan. Majority of RC buildings comprise of moment resisting frames with infill wall using brick or block masonry. The technical expertise required for the design of reinforced concrete buildings are available in major cities, however, the implementation and regulation mechanisms have been difficult to enforce. Therefore, the overall quality of RCC built stock of Pakistan can be categorized from average to poor.

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Report #164: Reinforced concrete frame with lightly reinforced masonry infill

by Laura Redmond, Reginald DesRoches

This type of home is a reinforced concrete frame building with brick infill on the second story. The infill may be lightly reinforced and the first story is either left open to prevent flooding in hurricanes, or later, when the individual has more money the bottom story is often infilled with masonry (which is not tied into the frame). This construction practice may make these structures vulnerable to seismic events as the building is effectively a large mass placed on top of a very flexible soft story. Additional vulnerabilities may stem from settlement of the wood pile foundations as the soil conditions are variable and generally no formal geotechnical surveys are done in Belize.

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Report #161: Confined and Internally Reinforced Concrete Block Masonry Building

by Diego Velasquez Jofre, Lars Abrahamczyk, Jochen Schwarz

The February 1976 earthquake caused severe damage to housing and buildings in Guatemala. Because many adobe houses were destroyed during the earthquake, there was greater interest in building with reinforced concrete block masonry structures after the event. This building type can now be found throughout Guatemala. Reinforced concrete block masonry structures are primarily used for family housing, both in cities and in rural Guatemala. The main load-bearing elements are masonry walls with concrete block walls reinforced with vertical and horizontal reinforced concrete elements in addition to internal steel reinforcement bars placed in the hollow cores of the concrete blocks. After the 1976 earthquake several guidelines were published on the construction of masonry block buildings, but the first formal standard/code was established in 2000, the Recommended Structural Standards of Design for the Republic of Guatemala -AGIES. The main parameters for structural design are incorporated in chapter No. 9  Mamposteria Reforzada. Nowadays reinforced concrete block masonry houses are constructed all over the country by governmental institutions for low-income classes. Currently this type of structure is the most widely built in Guatemala.

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Report # 114 : Stonework building with wooden timber roof

by Masoud N. Ahari, Alireza Azarbakht

Stonework buildings are a common type of rural construction in many parts of Iran (Figure 32). It is widely used in the mountainous areas because of the ease of attaining the building material. More than 71,000 stonework buildings were built in 1968-1972 in comparison to 54,000 brick masonry buildings in these years [1]. Unfortunately these buildings are often found in highly seismic parts of Iran (see maps on WHE webpage for Iran). Buildings of this type are up to two stories high, with height/width aspect ratio on the order of 0.3-0.5. The building materials consists of stone, wood, mud mortar and straw. The major elements of these systems are stonewalls which carry both gravity and lateral loads. These walls consist of stone or stone ballast with mud mortar and straw. For reasons of thermal insulation the thickness of these walls is not less than 50 centimeters (usually 70 centimeters). Details of wall are shown in Figures 11 to 20. The roof includes wooden joists and a set of secondary joists which are plastered with a thick layer of mud (Figures 21 and 22). Different views of this kind of building are shown in Figures 1 to 3. Also a typical building view, plan and layout are shown in Figures 4 to 10. Weak points of this construction type are: the presence of a heavy roof; inadequate behavior of the walls under out-of-plain forces (Figures 23 and 24); poor shear capacity of the mortar; inadequate connection between roof and walls; inadequate connection between intersecting walls; and lack of diaphragm action in floors and roof where the roof elements (wooden beams) do not work together in earthquakes and may collapse (Figures 25 and 27). In general, this kind of structure is frequently used as a house and stable in mountainous villages, but its earthquake performance is not acceptable. Any proper rehabilitation techniques may save many people’s lives.

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Report # 118 : Earring system (Shekanj) in dome-roof structures with unreinforced brick and adobe materials

by Nima T. Bekloo

This building structure derives its name from the four earrings that are constructed at the four corners of a rectangular building at the spring level of dome roof. This structural system was developed due to the lack of of wood and stone. It was widely constructed more than 3 thousand years ago, after the invention of the dome-roof structures in the Old Persian Empire (Ashkanian & Sasanian). The main problem with the dome-roof building was to transform the rectangular or polygonal plan of the group of walls into the circular plan at the spring level of dome roof. They used to construct the first row of dome and then construct another row on top of previous one with a little offset closer to the center of the dome circle and so on. That was too difficult to construct. This system was invented to resolve this problem. In this system, once the walls were constructed, four earrings (shekanj) built upon four corners of walls intersections, and then it was much easier to build a dome over these. It is an ideal system to resist vertical and gravity loads and transform them into horizontal and shear loads. For lateral loads, domes behave like trusses and distribute the load to the other parts of the structure creating a perfect load path.

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Report # 117 : Four arches (Char taaqi) with dome-roof structures, and unreinforced brick and adobe materials.

by Nima T. Bekloo

The ‘Four arches’ or Char Taaqi (in Persian) derives its name from the four arches that connects tops of four timber or masonry piers enclosing the space. It is an equilateral architectural unit consisting of four arches or short Barrel vaults between four corner piers, with a dome over the central square; this square and the lateral bays under the arches or barrel vaults together constitute a room of cruciform ground plan. This structural system developed about 2500 years ago, after earring system in the Old Persian Empire (Sasanian age). Main goal of this building system was to create wide openings at four side of the structure. This building system was used for special places that carry high population like fire temple (place where Persians worshiped the Fire God), mosque, bazaar and other public places. This is not that difficult to built a dome over four arches. Further, dome structures are ideal for large span structures against gravity loads as it transforms them into horizontal and shear loads. In addition, for lateral loads, domes behave like a truss and distribute the load to other parts of the structure developing a perfect load path. This construction system has been considered, the most prominent structural system in traditional Iranian architecture. These are basically monumental buildings developed close to desert where there was not enough construction materials that could take tensile stresses.

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