story. Extensive shear cracks were found in URM walls . Seismic capacity of the collapsed building was preliminarily calculated according to the Japanese Standard for Seismic Evaluation, neglecting the effects of URM walls to structural behavior. The structure was estimated to fail in flexure and its ultimate strength was 0.14 in terms of base shear coefficient.

Photo 11-1: General view of the mosque
Photo 11-3: Interior damage

(12) High School, Battal (11/20)
* Construction: RC with URM (brick) wall
* Number of stories: 1

* Use: School
The school consisted of several URM buildings (Photo 12-1). Two of them were completely destroyed (Photos 12-2 and12-3). The building collapse reportedly killed 35 and injured 150 out of 450 students.

Photo 12-1: General view of school
Photo 12-2: Collapsed school Photo

1.3 Abottabad
Abottabad is located about 40km SW from the epicenter. Serious damage to beam-column connections resulting from poor reinforcement detailing was found in RC buildings. It should also be pointed out that some damaged buildings were not properly repaired.

(13) Restaurant Building (name unknown) (11/23)
* Construction: RC with URM wall, constructed in around 1998 to 2000
* Number of stories: 3
* Use: Restaurant
This building was located on the National Road N-35 (Abottabad-Mansehra Road) and lost its first and second stories (Photo 13-1). Beam reinforcement was straightly anchored in exterior columns and was not bent and embedded into beam-column core concrete (Photo13-2). Beam-column joints did not have lateral reinforcement. Such detailing did not form rigid connections and moment resisting frames, and it could easily lead to beam-column connection failure.
Typical column sections were 25cm x 40cm. Their lateral reinforcement having a diameter of 7mm was provided at a space of 30cm with 90-degree hooks at ends (Photo 13-3).
Schmidt hammer tests were made on a beam of the collapsed building and the estimated strength was 17 N/mm2 (R = 32).

Photo 13-1: General view of collapsed restaurant
Photo 13-4: Damaged neighboring building

(14) Department Store (name unknown) (11/23)
* Construction: RC with URM wall, constructed in 2004
* Number of stories: 3
* Use: Department store
This building was located on the National Road N-35 and failed in the first story . Beam reinforcement was straightly anchored within a narrow column . Beam reinforcement in the transverse direction straightly went through the beam-column connection and terminated at the column surface without any bent anchorage into the core concrete. Since no lateral reinforcement was provided in the beam-column joints as was the common practice in Pakistan, the concrete cover spalled off the joint exposing buckled column rebars. Reinforcing bars failed in a brittle manner without showing necking at the fractured section .
Schmidt hammer tests were made on a column of the first floor and the estimated strength was 22 N/mm2 (R = 38).

1.4 Balakot
(15) Houses in Balakot (11/23)
Balakot is located about 25km NW from the epicenter. In central Balakot, 70% to 80% (visual survey) RC buildings and houses were totally destroyed (Photo 15-1). Damage was especially devastating on the hillside area, and almost all buildings there were totally destroyed due to landslide and shaking (Photo 15-2). Poor reinforcement detail was generally found in beams such as (Photo 15-3): (a) Beam rebars running outside the column reinforcement cage; (b) Beam rebars straightly terminated at the surface of exterior columns without bent anchorage into core concrete; (c) No shear reinforcement at beam-column joints; (d) insufficient overlap length at rebar joints in beams and slabs, leading to pull-out joint failure.
Schmidt hammer tests were made on a beam of a collapsed house and the estimated strength was 15 N/mm2 (R = 33).

Photo 15-1: Damage to buildings and houses in central Balakot

1.5 Muzaffarabad
(16) Houses and buildings in Muzaffarabad (11/24)
Muzaffarabad is located about 10km SW of the epicenter. Buildings and houses were often constructed on steep slopes and they were eventually devastated associated with slope failures (photo 16-1). Other structural damage to RC houses and buildings was attributed to the poor anchorage at beam-column connections as was found in other cities ). Since beam rebars were straightly developed and terminated in the connection, they were easily pulled out of the connection and did not form RC moment resisting frames. Reinforcement was often found less ductile, and rebars did not show necking at their fractured sections .
Schmidt hammer tests were made on a survived ward of the Combined Military Hospital which partially lost the first story and the estimated strength was 20 N/mm2 (R =39).
It should also be noticed that some buildings with serious damage and tilting were occupied as they were before the quake, although they were potentially vulnerable to aftershocks. Development of quick inspection system and technical guides to identify buildings with potentially vulnerable to aftershock were needed in this city.

Photo 16-4: Combined Military Hospital
Photo 16-6: Continuously open shops

2. Findings from Damage Observations and Recommendations
(1) Concrete Quality
In Islamabad and other affected areas, no ready-mixed concrete is used at construction sites. Honeycombs are often found in members and the ratio of coarse and fine aggregate is different in each construction. Concrete strengths estimated from Schmidt hammer tests in some investigated buildings are summarized below together with their structural damage.

Building Structural Damage Estimated Strength(s) (N/mm2)
(1) Margala Towers Building No.4 collapsed 12*, 17*, 15
(2) Al-Mustafa Towers No damage 28
(3) Park Towers Light (Cracks in beams) 33
(4) Al-Safa Heights No damage 26
(9) Primary Schoo, Battal Light 21
(10) Primary and High School, Battal Collapsed 8
(13) Restaurant, Abottabad Collapsed 17
(14) Department Store, Abottabad Collapsed 22
(15) House, Balakot Collapsed 15